How to make a multi dimensional array Bash

Question

So I have been looking and looking online to figure out how to make a two dimensional array. Like I kinda understand a one line linear array. But when I look online all I see is a bunch of code that I don't even understand what each component of the code does. Thanks for whoever answers.

Can you please explain important parts of the code to me and there function.

Have you seen this post: http://stackoverflow.com/questions/11233825/multi-dimensional-arrays-in-bash — paddy, Feb 27 '13 at 00:51
@paddy All this says is to use python. Also bash can now do multidim with bash 4.0 — Lifetake, Feb 27 '13 at 00:54

score 3 · Accepted Answer · answered Feb 27 '13 at 00:54

3

A multidimensional array is just a special case of an associative array in bash 4:

# Make myarray an associative array
declare -A myarray 

# Assign some random value
myarray[3,7]="foo"

# Access it through variables
x=3 y=7
echo "${myarray[$x,$y]}"

It works because "3,7" is just a string like any other. It could just as well have been "warthog" or "ThreeCommaSeven". As long as everything else in your code turns the indices 3 and 7 into the string "3,7", it'll work just like a multidimensional array.

answered Feb 27 '13 at 00:54

that other guy

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would't this still be linear though @that other guy – Lifetake Feb 27 '13 at 00:57
so what would be the output of this 'foo'? So how does that make it 2d ? Can you give a small ex with output please. Thanks sorry for my no understanding @that other guy – Lifetake Feb 27 '13 at 01:02
This is as good a way as any to implement a multidimensional array. If what you are really looking for is an array-of-arrays, where something like `${x[2]}` is another array, then `bash` is not the language for you. It's possible, but it quickly gets ugly, as you have to fake it with indirect parameter expansion and/or `eval`. – chepner Feb 27 '13 at 01:11
1

@Lifetake This is a complete example, and it outputs `foo`. It's 2D because you index it with two integer variables, just like a 2D array in any other language. It's not linear because no bash arrays are ever linear, they're always sparse. – that other guy Feb 27 '13 at 16:26

score 2 · Answer 2 · edited Aug 22 '18 at 00:41

2

If you want to list the elements without knowing in advance their number, a very handy solution:

a=()
a+=( Mexico,2000 )
a+=( Canada,3000 )

for row in ${a[@]};
do
    echo place: ${row%%,*} airplanes: ${row##*,}
done

edited Aug 22 '18 at 00:41

Stephen Rauch

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answered Aug 22 '18 at 00:20

Alex

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How to make a multi dimensional array Bash

2 Answers2