1 | ---
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2 | in_progress: yes
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3 | default_highlighter: oils-sh
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4 | ---
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5 |
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6 | Streams, Tables and Processes - awk, R, xargs
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7 | =============================================
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8 |
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9 | *(July 2024)*
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10 |
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11 | This is a long, "unified/orthogonal" design for:
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12 |
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13 | - Streams: [awk]($xref) delimited lines, regexes
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14 | - Tables: like data frames with R's dplyr or Pandas, but with the "exterior"
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15 | TSV8 format
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16 | - Processes: xargs -P in parallel
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17 |
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18 | There's also a relation to:
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19 |
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20 | - Trees: `jq`, which will be covered elsewhere.
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21 |
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22 | It's a layered design. That means we need some underlying mechanisms:
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23 |
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24 | - `eval` and positional args `$1 $2 $3`
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25 | - `ctx` builtin
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26 | - Data langauges: TSV8
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27 | - Process pool / event loop primitive
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28 |
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29 | It will link to:
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30 |
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31 | - Oils blog posts (old)
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32 | - Zulip threads (recent)
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33 | - Other related projects (many of them)
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34 |
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35 | <div id="toc">
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36 | </div>
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37 |
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38 | ## Intro With Code Snippets
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39 |
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40 | Let's introduce this with a text file
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41 |
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42 | $ seq 4 | xargs -n 2 | tee test.txt
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43 | 1 2
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44 | 3 4
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45 |
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46 | xargs does splitting:
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47 |
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48 | $ echo 'alice bob' | xargs -n 1 -- echo hi | tee test2.txt
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49 | hi alice
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50 | hi bob
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51 |
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52 | Oils:
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53 |
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54 | # should we use $_ for _word _line _row? $[_.age] instead of $[_row.age]
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55 | $ echo 'alice bob' | each-word { echo "hi $_" } | tee test2.txt
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56 | hi alice
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57 | hi bob
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58 |
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59 | Normally this should be balanced
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60 |
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61 | ### Streams - awk
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62 |
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63 | Now let's use awk:
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64 |
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65 | $ cat test.txt | awk '{ print $2 " " $1 }'
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66 | 2 1
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67 | 4 3
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68 |
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69 | In YSH:
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70 |
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71 | $ cat test.txt | chop '$2 $1'
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72 | 2 1
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73 | 4 3
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74 |
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75 | It's shorter! `chop` is an alias for `split-by (space=true, template='$2 $1')`
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76 |
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77 | With a template, for static parsing:
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78 |
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79 | $ cat test.txt | chop (^"$2 $1")
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80 | 2 1
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81 | 4 3
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82 |
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83 | It's shorter! With a block:
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84 |
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85 | $ cat test.txt | chop { mkdir -v -p $2/$1 }
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86 | mkdir: created directory '2/1'
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87 | mkdir: created directory '4/3'
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88 |
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89 | With no argument, it prints a table:
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90 |
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91 | $ cat test.txt | chop
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92 | #.tsv8 $1 $2
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93 | 2 1
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94 | 4 3
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95 |
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96 | $ cat test.txt | chop (names = :|a b|)
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97 | #.tsv8 a b
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98 | 2 1
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99 | 4 3
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100 |
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101 | Longer examples with split-by:
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102 |
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103 | $ cat test.txt | split-by (space=true, template='$2 $1')
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104 | $ cat test.txt | split-by (space=true, template=^"$2 $1")
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105 | $ cat test.txt | split-by (space=true) { mkdir -v -p $2/$1 }
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106 | $ cat test.txt | split-by (space=true)
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107 | $ cat test.txt | split-by (space=true, names= :|a b|)
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108 | $ cat test.txt | split-by (space=true, names= :|a b|) {
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109 | mkdir -v -p $a/$b
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110 | }
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111 |
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112 | With must-match:
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113 |
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114 | $ var p = /<capture d+> s+ </capture d+>/
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115 | $ cat test.txt | must-match (p, template='$2 $1')
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116 | $ cat test.txt | must-match (p, template=^"$2 $1")
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117 | $ cat test.txt | must-match (p) { mkdir -v -p $2/$1 }
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118 | $ cat test.txt | must-match (p)
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119 |
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120 | With names:
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121 |
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122 | $ var p = /<capture d+ as a> s+ </capture d+ as b>/
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123 | $ cat test.txt | must-match (p, template='$b $a')
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124 | $ cat test.txt | must-match (p)
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125 | #.tsv8 a b
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126 | 2 1
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127 | 4 3
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128 |
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129 | $ cat test.txt | must-match (p) {
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130 | mkdir -v -p $a/$b
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131 | }
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132 |
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133 | Doing it in parallel:
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134 |
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135 | $ cat test.txt | must-match --max-jobs 4 (p) {
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136 | mkdir -v -p $a/$b
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137 | }
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138 |
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139 | ### Tables - Data frames with dplyr (R)
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140 |
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141 | $ cat table.txt
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142 | size path
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143 | 3 foo.txt
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144 | 20 bar.jpg
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145 |
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146 | $ R
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147 | > t=read.table('table.txt', header=T)
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148 | > t
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149 | size path
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150 | 1 3 foo.txt
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151 | 2 20 bar.jpg
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152 |
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153 | ### Processes - xargs
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154 |
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155 | We already saw this! Because we "compressed" awk and xargs together
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156 |
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157 | What's not in the streams / awk example above:
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158 |
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159 | - `BEGIN END` - that can be separate
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160 | - `when [$1 ~ /d+/] { }`
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161 |
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162 | ## Background / References
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163 |
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164 | - Shell, Awk, and Make Should be Combined (2016)
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165 | - this is the Awk part!
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166 |
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167 | - What is a Data Frame? (2018)
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168 |
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169 | - Sketches of YSH Features (June 2023) - can we express things in YSH?
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170 | - Zulip: Oils Layering / Self-hosting
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171 |
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172 | - Language Compositionality Test: J8 Lines
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173 | - This whole thing is a compositionality test
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174 |
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175 | - read --split
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176 | - more feedback from Aidan and Samuel
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177 |
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178 | - What is a Data Frame?
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179 |
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180 | - jq in jq thread
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181 |
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182 | Old wiki pages:
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183 |
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184 | - <https://github.com/oilshell/oil/wiki/Structured-Data-in-Oil>
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185 | - uxy - closest I think - <https://github.com/sustrik/uxy>
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186 | - relies on to-json and jq for querying
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187 | - miller - I don't like their language - https://github.com/johnkerl/miller -
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188 | - jc - <https://github.com/kellyjonbrazil/jc>
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189 | - nushell
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190 | - extremely old thing -
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191 |
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192 | We're doing **all of these**.
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193 |
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194 | ## Concrete Use Cases
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195 |
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196 | - benchmarks/* with dplyr
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197 | - wedge report
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198 | - oilshell.org analytics job uses dplyr and ggplot2
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199 |
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200 | ## Intro
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201 |
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202 | ### How much code is it?
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203 |
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204 | - I think this is ~1000 lines of Python and ~1000 lines of YSH (not including tests)
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205 | - It should be small
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206 |
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207 | ### Thanks
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208 |
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209 | - Samuel - two big hints
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210 | - do it in YSH
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211 | - `table` with the `ctx` builtin
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212 | - Aidan
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213 | - `read --split` feedback
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214 |
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215 |
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216 | ## Tools
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217 |
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218 | - awk
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219 | - streams of records - row-wise
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220 | - R
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221 | - column-wise operations on tables
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222 | - `find . -printf '%s %P\n'` - size and path
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223 | - generate text that looks like a table
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224 | - xargs
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225 | - operate on tabular text -- it has a bespoke splitting algorithm
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226 | - Opinionated guide to xargs
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227 | - table in, table out
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228 | - jq - "awk for JSON"
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229 |
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230 |
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231 | ## Concepts
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232 |
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233 | - TSV8
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234 | - aligned format SSV8
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235 | - columns have types, and attributes
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236 | - Lines
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237 | - raw lines like shell
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238 | - J8 lines (which can represent any filename, any unicode or byte string)
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239 | - Tables - can be thought of as:
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240 | - Streams of Rows - shape `[{bytes: 123, path: "foo"}, {}, ...]`
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241 | - this is actually <https://jsonlines.org> , and it fits well with `jq`
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242 | - Columns - shape `{bytes: [], path: []}
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243 |
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244 | ## Underlying Mechanisms in Oils / Primitives
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245 |
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246 | - blocks `value.Block` - `^()` and `{ }`
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247 | - expressions `value.Expr` - `^[]` and 'compute [] where []'
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248 |
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249 | - eval (b, vars={}, positional=[])
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250 |
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251 | - Buffered for loop
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252 | - YSH is now roughly as fast as Awk!
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253 | - `for x in (stdin)`
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254 |
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255 | - "magic awk loop"
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256 |
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257 | with chop {
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258 | for <README.md *.py> {
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259 | echo _line_num _line _filename $1 $2
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260 | }
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261 | }
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262 |
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263 | - positional args $1 $2 $3
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264 | - currently mean "argv stack"
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265 | - or "the captures"
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266 | - this can probably be generalized
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267 |
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268 | - `ctx` builtin
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269 | - `value.Place`
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270 |
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271 | TODO:
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272 |
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273 | - split() like Python, not like shell IFS algorithm
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274 |
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275 | - string formatting ${bytes %.2f}
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276 | - ${bytes %.2f M} Megabytes
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277 | - ${bytes %.2f Mi} Mebibytes
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278 |
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279 | - ${timestamp +'%Y-m-%d'} and strfitime
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280 |
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281 | - this is for
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282 |
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283 | - floating point %e %f %g and printf and strftime
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284 |
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285 | ### Process Pool or Event Loop Primitive?
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286 |
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287 | - if you want to display progress, then you might need an event loop
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288 | - test framework might display progress
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289 |
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290 | ## Matrices - Orthogonal design in these dimensions
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291 |
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292 | - input: lines vs. rows
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293 | - output: string (Str, Template) vs. row vs. block execution (also a row)
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294 | - execution: serial vs. parallel
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295 | - representation: interior vs. exterior !!!
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296 | - Dicts and Lists are interior, but TSV8 is exterior
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297 | - and we have row-wise format, and column-wise format -- this always bugged me
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298 | - exterior: human vs. machine readable
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299 | - TSV8 is both human and machine-readable
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300 | - "aligned" #.ssv8 format is also
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301 | - they are one format named TSV8, with different file extensions. This is
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302 | because it doesn't make too much sense to implement SSV8 without TSV8. The
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303 | latter becomes trivial. So we call the whole thing TSV8.
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304 |
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305 | This means we consider all these conversions
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306 |
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307 | - Line -> Line
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308 | - Line -> Row
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309 | - Row -> Line
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310 | - Row -> Row
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311 |
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312 | ## Concrete Decisions - Matrix cut off
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313 |
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314 | Design might seem very general, but we did make some hard choices.
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315 |
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316 | - push vs. pull
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317 | - everything is "push" style I think
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318 | - buffered vs. unbuffered, everything
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319 |
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320 | - List vs iterators
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321 | - everything is either iterable pipelines, or a List
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322 |
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323 |
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324 | [OSH]: $xref
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325 | [YSH]: $xref
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326 |
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327 |
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328 | ## String World
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329 |
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330 | **THESE ARE ALL THE SAME ALGORITHM**. They just have different names.
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331 |
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332 | - each-line
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333 | - each-row
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334 | - split-by (/d+/, cols=:|a b c|)
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335 | - chop
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336 | - if-match
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337 | - must-match
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338 | - todo
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339 |
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340 | should we also have: if-split-by ? In case there aren't enough columns?
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341 |
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342 | They all take:
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343 |
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344 | - string arg ' '
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345 | - template arg (^"") - `value.Expr`
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346 | - block arg
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347 |
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348 | for the block arg, this applies:
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349 |
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350 | -j 4
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351 | --max-jobs 4
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352 |
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353 | --max-jobs $(cached-nproc)
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354 | --max-jobs $[_nproc - 1]
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355 |
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356 | ### Awk Issues
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357 |
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358 | So we have this
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359 |
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360 | echo begin
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361 | var d = {}
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362 | cat -- @files | split-by (ifs=IFS) {
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363 | echo $2 $1
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364 | call d->accum($1, $2)
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365 | }
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366 | echo end
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367 |
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368 | But then how do we have conditionals:
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369 |
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370 | Filter foo { # does this define a proc? Or a data structure
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371 |
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372 | split-by (ifs=IFS) # is this possible? We register the proc itself?
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373 |
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374 | config split-by (ifs=IFS) # register it
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375 |
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376 | BEGIN {
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377 | var d = {}
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378 | }
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379 | END {
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380 | echo d.sum
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381 | }
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382 |
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383 | when [$1 ~ /d+/] {
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384 | setvar d.sum += $1
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385 | }
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386 |
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387 | }
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388 |
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389 | ## Table World
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390 |
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391 | ### `table` to construct
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392 |
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393 | Actions:
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394 |
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395 | table cat
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396 | table align / table tabify
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397 | table header (cols)
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398 | table slice (1, -1) or (-1, -2) etc.
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399 |
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400 | Subcommands
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401 |
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402 | cols
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403 | types
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404 | attr units
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405 |
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406 | Partial Parsing / Lazy Parsing - TSV8 is designed for this
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407 |
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408 | # we only decode the columns that are necessary
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409 | cat myfile.tsv8 | table --by-col (&out, cols = :|bytes path|)
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410 |
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411 | ## Will writing it in YSH be slow?
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412 |
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413 | - We concentrate on semantics first
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414 | - We can rewrite in Python
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415 | - Better: users can use **exterior** tools with the same interface
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416 | - in some cases
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417 | - they can write an efficient `sort-tsv8` or `join-tsv8` with novel algorithms
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418 | - Most data will be small at first
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419 |
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420 |
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421 | ## Applications
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422 |
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423 | - Shell is shared nothing
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424 | - Scaling to infinity on the biggest clouds
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425 |
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426 |
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427 | ## Extra: Tree World?
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428 |
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429 | This is sort of "expanding the scope" of the project, when we want to reduce scope.
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430 |
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431 | But YSH has both tree-shaped JSON, and table-shaped TSV8, and jq is a nice **bridge** between them.
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432 |
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433 | Streams of Trees (jq)
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434 |
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435 | empty
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436 | this
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437 | this[]
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438 | =>
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439 | select()
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440 | a & b # more than one
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441 |
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442 |
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443 | ## Pie in the Sky
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444 |
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445 | Four types of Data Languages:
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446 |
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447 | - flat strings
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448 | - JSON8 - tree
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449 | - TSV8 - table
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450 | - NIL8 - Lisp Tree
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451 | - HTML/XML - doc tree -- attributed text (similar to Emacs data model)
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452 | - 8ml
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453 |
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454 | Four types of query languaegs:
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455 |
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456 | - regex
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457 | - jq / jshape
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458 | - tsv8
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459 |
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460 |
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461 | ## Appendix
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462 |
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463 | ### Notes on Naming
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464 |
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465 | Considering columns and then rows:
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466 |
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467 | - SQL is "select ... where"
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468 | - dplyr is "select ... filter"
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469 | - YSH is "pick ... where"
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470 | - select is a legacy shell keyword, and pick is shorter
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471 | - or it could be elect in OSH, elect/select in YSH
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472 | - OSH wouldn't support mutate [average = bytes/total] anyway
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473 |
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474 | dplyr:
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475 |
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476 | - summarise vs. summarize vs. summary
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477 |
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478 |
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479 |
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480 |
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481 |
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