Sorting tab delimited numbers by column with pure bash script. - bash

Question

Im stuck on some homework. The requirements of the assignment are to accept an input file and perform some statistics on the values. The user may specify whether to calculate the statistics by row or by value. The shell script must be pure bash script so I can't use awk, sed, perl, python etc.
sample input:
1 1 1 1 1 1 1
39 43 4 3225 5 2 2
6 57 8 9 7 3 4
3 36 8 9 14 4 3
3 4 2 1 4 5 5
6 4 4814 7 7 6 6
I can't figure out how to sort and process the data by column. My code for processing the rows works fine.
# CODE FOR ROWS
while read -r line
echo $(printf "%d\n" $line | sort -n) | tr ' ' \\t > sorted.txt
....
#I perform the stats calculations
# for row line by working with the temp file sorted.txt
done
How could I process this data by column? I've never worked with shell script so I've been staring at this for hours.

Answer 1

If you wanted to analyze by columns you'll need the cols value first (number of columns). head -n 1 gives you the first row, and NF counts the number of fields, giving us the number of columns.
cols=$(head -n 1 test.txt | awk '{print NF}');
Then you can use cut with the '\t' delimiter to grab every column from input.txt, and run it through sort -n, as you did in your original post.
$ for i in `seq 2 $((cols+1))`; do cut -f$i -d$'\t' input.txt; done | sort -n > output.txt
For rows, you can use the shell built-in printf with the format modifier %dfor integers. The sort command works on lines of input, so we replace spaces ' ' with newlines \n using the tr command:
$ cat input.txt | while read line; do echo $(printf "%d\n" $line); done | tr ' ' '\n' | sort -n > output.txt
Now take the output file to gather our statistics:
Min: cat output.txt | head -n 1
Max: cat output.txt | tail -n 1
Sum: (courtesy of Dimitre Radoulov): cat output.txt | paste -sd+ - | bc
Mean: (courtesy of porges): cat output.txt | awk '{ $total += $2 } END { print $total/NR }'
Median: (courtesy of maxschlepzig): cat output.txt | awk ' { a[i++]=$1; } END { print a[int(i/2)]; }'
Histogram: cat output.txt | uniq -c
8 1
3 2
4 3
6 4
3 5
4 6
3 7
2 8
2 9
1 14
1 36
1 39
1 43
1 57
1 3225
1 4814