How to initialize an array of arrays in awk?

Question

Is it possible to initialize an array like this in AWK ?

Colors[1] = ("Red", "Green", "Blue") Colors[2] = ("Yellow", "Cyan", "Purple") 

And then to have a two dimensional array where Colors[2,3]="Purple".

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From another thread I understand that it's not possible ( "sadly, there is no way to set an array all at once without abusing split()" ). Anyways I want to be 100% sure and I'm sure that there are others with the same question.

I am looking for the easiest method to initialize arrays like the one above, will be nice to have it well written.

Answer 1

You can create a 2-dimensional array easily enough. What you can't do, AFAIK, is initialize it in a single operation. As dmckee hints in a comment, one of the reasons for not being able to initialize an array is that there is no restriction on the types of the subscripts, and hence no requirement that they are pure numeric. You can do multiple assignments as in the script below. The subscripts are formally separated by an obscure character designated by the variable SUBSEP, with default value 034 (U+001C, FILE SEPARATOR). Clearly, if one of the indexes contains this character, confusion will follow (but when was the last time you used that character in a string?).

BEGIN {     Colours[1,1] = "Red"     Colours[1,2] = "Green"     Colours[1,3] = "Blue"     Colours[2,1] = "Yellow"     Colours[2,2] = "Cyan"     Colours[2,3] = "Purple" } END {     for (i = 1; i <= 2; i++)         for (j = 1; j <= 3; j++)             printf "Colours[%d,%d] = %s\n", i, j, Colours[i,j]; } 

Example run:

$ awk -f so14063783.awk /dev/null Colours[1,1] = Red Colours[1,2] = Green Colours[1,3] = Blue Colours[2,1] = Yellow Colours[2,2] = Cyan Colours[2,3] = Purple $ 

Answer 2

If you have GNU awk, you can use a true multidimensional array. Although this answer uses the split() function, it most certainly doesn't abuse it. Run like:

awk -f script.awk 

Contents of script.awk:

BEGIN {      x=SUBSEP      a="Red" x "Green" x "Blue"     b="Yellow" x "Cyan" x "Purple"      Colors[1][0] = ""     Colors[2][0] = ""      split(a, Colors[1], x)     split(b, Colors[2], x)      print Colors[2][3] } 

Results:

Purple