Prepending information from filenames into files

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# 1  
Prepending information from filenames into files

I would like to know how to take information from a filename and place it into the text of the same file. Let's say I have a file called height_2_width_1.txt containing data that is related to a height of 2 and a width of 1, and the text originally looks like this:

3 4
2 5
5 2
7 5
where these two columns are two other variables (depth and brightness, or whatever). Basically, I would like to add two columns to this file, based on the height and width of the first file, such that the end result would look like this:

2 1 3 4
2 1 2 5
2 1 5 2
2 1 7 5
So, if I did this, I would have the height 2 and width 1 information put in columns next to the other data related to these particular heights and weights. So a case with a depth of 3 and brightness of 4 would have the height of 2 and width of 1 prepended to it.

And then I have multiple files named height_X_width_Y.txt, such that I have an array for height and width (let's say 1,2,3,4 for each X and Y variable, so I have the following files: height_1_width_1.txt, height_1_width_2.txt, etc). I would like to create a perl script that does the same thing for all of the files. I'm just not sure what the best way would be to do this would be. I hope this made sense. Smilie

This is my attempt thus far, but I haven't been able to get it to work:

#!/usr/bin/perl -w

my @height=(1,2,3,4);

my @width=(1,2,3,4);

foreach my $height (@height)
    foreach my $width (@width)
		$filename = "height_${height}_width_${width}.txt";
		system("sed -i "" '1,4 ${height} ${width}' $filename");

Last edited by pludi; 06-02-2011 at 10:55 AM..
# 2  
This bash script will do it for you:


for i in `seq 1 $max_i`; do
        for j in `seq 1 $max_j`; do
                if [ -f height_${i}_width_${j}.txt ]; then
                        echo "Processing file height_${i}_width_${j}.txt"
                        sed -i "s/^/$i $j /g"  height_${i}_width_${j}.txt
                        echo "File height_${i}_width_${j}.txt does not exist"

You only have to change max_i and max_j to the maximum values for height and width.
# 3  
The only problem is that, since I'm doing this on Mac OSX, it's telling me that the command seq is not found:

line 15: seq: command not found
What else would I use?
# 4  
Instead of `seq ` $max_i` you could use {1..3} (if you are using the bash shell). The only downside is that you have to use the actual value as the max value and not a variable.

Alternatively, you could try to see if you have jot installed - it should be the Mac OS equivalent for seq.
# 5  
Well, I tried both of those, and those fixed that problem, but then I got another error message (this time with sed):

sed: 1: "height_1_width_1.txt": command c expects \ followed by text
# 6  
I don't have a Mac OS sed to test it with, but you could try it by changing the sed line to:
sed -i "s/^/${i} ${j} /g"  height_${i}_width_${j}.txt

# 7  
Well, I tried that, and I got the exact same error message.

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