bash: make array from table

Question

I am operating with the multiple column data: ID,num,score

7LMQ,Y6G,1.99
7LAA,Y65,2.95
7LZZ,Y55,8.106
7LDD,YAA,9.063
7N66,0HG,6.042
7444,HOP,5.02
7LJF,HEI,5.14
7LFD,LAL,4.128
7KCV,Cho,4.31
7GHJ,Ro,9.045

using some simple script I need to create two bash arrays from this data:

a simple array containing elemements from the second column:

sdf_lists=("Y6G" "Y65" "Y55" "YAA" "0HG" "HOP" "HEI" "LAL" "Cho" "Ro")
an associative array made from the elements of the 2nd and the 1st columns:

dataset=( [Y6G]=7LMQ [Y65]=7LAA [Y55]=7LZZ [YAA]=7LDD [0HG]=7N66 [HOP]=7444 [HEI]=7LJF [LAL]=7LFD [Cho]=7KCV [Ro]=7GHj ).

Do I need something complex like AWK to achive it or simple GREP solution will work as well?

Please, never show text with images. They are not searchable, not copy-paste-able and much heavier than needed. Moreover they affect accessibility negatively. Please copy-paste the text in your question and format it properly, instead. And do not forget to explain what format you use (CSV, TSV...) — Renaud Pacalet
– Renaud Pacalet, Commented Dec 15, 2021 at 12:19
I am terrible sorry, actually I tried to paste it in csv initially... so it's been edited :-) — Hot JAMS
– Hot JAMS, Commented Dec 15, 2021 at 12:22
I would do this completely in bash, i.e. [1] read the file line by line, [2] split each line into the fields, and [3] populate the two arrays. Don't forget to think about, whether the values in the second column can occur multiple times, or are unique (like in your example). — user1934428
– user1934428, Commented Dec 15, 2021 at 12:47

glenn jackman · Accepted Answer · 2021-12-15 18:56:12Z

2

bash by itself is all you need

declare -a sdf_lists=()
declare -A dataset=()

while IFS=, read -r id sdf value; do
  sdf_lists+=("$sdf")
  dataset[$id]="$sdf"
done < file.csv

declare -p sdf_lists dataset

result

declare -a sdf_lists=([0]="Y6G" [1]="Y65" [2]="Y55" [3]="YAA" [4]="0HG" [5]="HOP" [6]="HEI" [7]="LAL" [8]="Cho" [9]="Ro")
declare -A dataset=([7LMQ]="Y6G" [7LJF]="HEI" [7444]="HOP" [7GHJ]="Ro" [7KCV]="Cho" [7N66]="0HG" [7LFD]="LAL" [7LZZ]="Y55" [7LDD]="YAA" [7LAA]="Y65" )

To address Andre Wildberg's appropriate concern about CSV data, with bash 5.1, we can do

enable -f /usr/local/lib/bash/csv csv     # your location may be different

while IFS= read -r line; do
  csv -a fields "$line"
  sdf_lists+=("${fields[1]}")
  dataset[${fields[0]}]="${fields[1]}"
done < file.csv

Or, use a tool like python or ruby that ship with CSV modules in their standard library.

edited Dec 15, 2021 at 18:56

answered Dec 15, 2021 at 17:45

glenn jackman

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2 Comments

Andre Wildberg Over a year ago

Careful: This fails on quoted commas and probably all sorts of whitespace characters.

glenn jackman Over a year ago

It would have trouble with quoted commas, but not whitespace.

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