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write a matrix element, if the "if" condition satisfies

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# 1  
Old 08-28-2012
write a matrix element, if the "if" condition satisfies
Hi All,

I would like to check a condition in a nxm matrix and if the condition satisfies then, I need to write the matrix element in the output file.

For example, I have a matrix like this:
1 2 3 4 5
2 3 4 5 1
3 4 5 1 2
4 5 1 2 3
5 1 2 3 4

and i need to test if the difference with the previous column as well as with the first column is more than 2; then I need to write that particular matrix element in the output file.

I tried this:

Code:
awk '{for(i=1; i<=NF; i++) {if ((($i-$1) > 2) && (($(i+1)-$i > 2)) print $i; else 0}}' inputmatrix > output

but filed. Can anyone help me in this regard? your replies are highly appreciated.

Warm regards
# 2  
Old 08-28-2012
I think your condition is wrong...

Tried this getting all 0..

Code:
awk '{for(i=2; i<=NF; i++) {if ((($i-$1) > 2) && (($(i)-$(i-1) > 2))) print $i; else { print "0" }} }' file

This User Gave Thanks to pamu For This Post:
Fredrick
# 3  
Old 08-28-2012
Hi Pamu,

Thanks for your reply.

But the problem here is, irrespective of the value in the condition, I need to write the matrix element (that means, the row and column number) in the output file. The difference with the first column and the difference with the previous column both should satisfy the conditions. I didn't get your code, why you have started with i=2?

A small modification in my previous code:

Code:
awk '{for(i=1; i<=NF; i++) {if (($i-$1) && ($(i+1)-$i) > 1) print i; else { print "0"}}}' input > output

The catch here is, I need to write the matrix element not the value at the matrix element, which satisfy the condition?

your replies are highly appreciated.

Warm regards
# 4  
Old 08-28-2012
What's the expected output? Do you want to consider the absolute differences?
This User Gave Thanks to elixir_sinari For This Post:
Fredrick
# 5  
Old 08-28-2012
Thanks elixir sinari, The output should be the number., like [1,2] or [4,5]..etc. It should be the matrix element number.

---------- Post updated at 01:28 PM ---------- Previous update was at 01:18 PM ----------

Thanks elixir sinari, If the difference is more than "1", then I need to write the matrix element (in which row and which column) is satisfying the condition. I tried the following, but getting 0 for all in my output.

Code:
awk '{for(i=1; i<=NF; i++) {for(j=1; j<=NR; j++) {if (($i-$1) && ($(i+1)-$i) > 1) print "[i,j]"; else { print "0"}}}}' input > output

[i,j] is the m,n element which is satisfying the condition. your replies are highly appreciated.

warm regards
# 6  
Old 08-28-2012
If I got you right, try this:
Code:
awk '{for (i=2;i<=NF;i++) if (($i-$1)>2 && $i-$(i-1)>2) print "line ", NR, ", field ", i}' infile

Hey, you're changing targets!
Code:
awk '{for (i=2;i<=NF;i++) if (($i-$1)>1 && $i-$(i-1)>1) print "[", NR, ",", i,"]"}' infile

This User Gave Thanks to RudiC For This Post:
Fredrick
# 7  
Old 08-28-2012
Hi

I have started with i=2 because, for i=1 while subtracting with column 1 its value is never greater than 2.

Try below code..

I have modified file to check the output....

Code:
cat file
1 2 5 4 5
2 3 4 5 1
3 4 5 1 2
4 5 1 2 3
5 1 2 8 4

$  awk '{for(i=2; i<=NF; i++) {if ((($i-$1) > 2) && (($(i)-$(i-1) > 2))) print NR,i; else { print "0" }} }' file
0
3 1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4 5
0

Last edited by pamu; 08-28-2012 at 08:52 AM..
This User Gave Thanks to pamu For This Post:
Fredrick
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