how to access last index of array from split function inside awk?

Question

How can i do this using awk?

Example -

awk '{split($1,A,"."); print A[-1], $1, $2, $3, $4}'

Sample input and output.

Input

123 456 abc.def.ghi 789 
321 654 qaz.wsx.edc.rfv 987

Output

ghi 123 456 abc.def.ghi 789  
rfv 321 654 qaz.wsx.edc.rfv 987

can you clarify if you want to split first field or the third field? — Sundeep, Sep 26 '16 at 13:45

score 38 · Accepted Answer · answered Sep 26 '16 at 12:48

38

If your problem is exactly as the example in your question, take the answer from @muzido, $NF will give you the last field.

If you just want to know the last element of an array by split():

split() function will return you how many elements it has just "splitted", test with your code: awk '{print split($1,A,".")}' file you will see the number. Then you can just use it by:

awk '{n=split($1,A,"."); print A[n]}' file 
# n is the length of array A

answered Sep 26 '16 at 12:48

Kent

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@anshulgupta you can even: `print A[split($1,A,".")]` ;-) – Kent Sep 26 '16 at 12:54
Let me know if you can optimize it further before i finalize my code ;) – anshul gupta Sep 26 '16 at 12:57
1

@anshulgupta it is not a kind of "optimization", I think the line in my answer (with `n` variable), is more readable. – Kent Sep 26 '16 at 12:58

score 9 · Answer 2 · answered Sep 26 '16 at 12:47

9

If you have GNU awk, you can try the function length on a array:

awk '{split($1,A,"."); print A[length(A)]}'

answered Sep 26 '16 at 12:47

oliv

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`length()` function here is redundant – Kent Sep 26 '16 at 12:49
@Kent I agree that `split()` and `length()` are kind of redundant together. However I find nice to have `length()` working with an array. – oliv Sep 26 '16 at 12:52
@Oliv, it's sad that i can only mark one as correct answer! – anshul gupta Sep 26 '16 at 12:58
Why would you run length() on an array when split() just returned the length of the array? – Ed Morton Sep 26 '16 at 16:23

score 3 · Answer 3 · answered Sep 26 '16 at 13:44

3

Why not:

$ awk '{print A[split($3,A,".")],$0}' input.txt

Hope it helps!

answered Sep 26 '16 at 13:44

Lacobus

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score 1 · Answer 4 · answered Sep 26 '16 at 16:25

1

Kent already gave you the split() answer but you don't need split creating/using an array for this, e.g. with GNU awk for gensub():

$ awk '{print gensub(/.*\./,"",1,$3), $0}' file
ghi 123 456 abc.def.ghi 789
rfv 321 654 qaz.wsx.edc.rfv 987

answered Sep 26 '16 at 16:25

Ed Morton

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how to access last index of array from split function inside awk?

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