List unique values and count instances in .csv file

Shell Programming and Scripting
1

I need to take the second column of a .csv file and count the number of instances of each unique value in that same second column. I'd like the output to be value,count sorted by most instances. Thanks for any guidance!

Data example:

317476,317756,0
816063,318861,0
313123,319091,0
317020,318466,0
516779,166445,1
319020,318466,0
316729,316483,0
631299,317306,0
313933,317306,0
168032,318032,0
160183,317722,0
917710,312593,0
316559,317756,0
319424,317756,0

2

Try:

awk -F, '{A[$2]++}END{for(i in A)print i,A}' OFS=, infile | sort -t, -k2,2rn

317756,3
317306,2
318466,2
166445,1
312593,1
316483,1
317722,1
318032,1
318861,1
319091,1
1 Like
4

Where do I specify the input and output filenames?

5

I'd be tempted to use a Perl hash keyed on the values and sorted by value. eg.

perl -e 'while(<>){@record=split/,/,$_;$count{$record[1]}++;}for $key (reverse sort {$count{$a}<=>$count{$b}} keys %count){print "$key => $count{$key}\n"}'    tmp.dat
6

Looks great so far. I'm just going to verify the data against something else. Thanks for the quick reply!