How to Compare CSV Column using awk? - linux

Question

I receive and CSV like this:
column$1,column$2,column$
john,P,10
john,P,10
john,A,20
john,T,30
john,T,10
marc,P,10
marc,C,10
marc,C,20
marc,T,30
marc,A,10
I need so sum the values and display the name and results but column$2 needs to show the sum of values T separated from values P,A,C.
Output should be this:
column$1,column$2,column$3,column$4
john,PCA,40
john,T,40,CORRECT
marc,PCA,50
marc,T,30,INCORRECT
All i could do was extract the columns i need from the original csv:
awk -F "|" '{print $8 "|" $9 "|" $4}' input.csv >> output.csv
Also sort by the correct column:
sort -t "|" -k1 input.csv >> output.csv
And add a new column to the end of the csv:
awk -F, '{NF=2}1' OFS="|" input.csv >> output.csv
I managed to sum and display the sum by column$1 and $2, but i don't how to group different values from column$2:
awk -F "," '{col[$1,$2]++} END {for(i in col) print i, col[i]}' file > output

Answer 1

Awk is stream oriented. It processes input and outputs what you change. It does not do in file changes.
You just need to add a corresponding print
awk '{if($2 == "T") {print "MATCHED"}}'
If you want to output more than the "matched" you need to add it to the print
e.g. '{print $1 "|" $2 "|" $3 "|" " MATCHED"}'
or use print $0 as comment mentions above.

Answer 2

Assuming that "CORRECT" and "INCORRECT" are determined by comparing the "PCA" value to the "T" value, the following awk script should do the trick:
awk -F, -vOFS=, '$2=="T"{t[$1]+=$3;n[$1]} $2!="T"{s[$1]+=$3;n[$1]} END{ for(i in n){print i,"PCA",s[i]; print i,"T",t[i],(t[i]==s[i] ? "CORRECT" : "INCORRECT")} }' inputfile
Broken out for easier reading, here's what this looks like:
awk -F, -vOFS=, '
$2=="T" { # match all records that are "T"
t[$1]+=$3 # add the value for this record to an array of totals
n[$1] # record this name in our authoritative name list
}
$2!="T" { # match all records that are NOT "T"
s[$1]+=$3 # add the value for this record to an array of sums
n[$1] # record this name too
}
END { # Now that we've collected data, analyse the results
for (i in n) { # step through our authoritative list of names
print i,"PCA",s[i]
print i,"T",t[i],(t[i]==s[i] ? "CORRECT" : "INCORRECT")
}
}
' inputfile
Note that array order is not guaranteed in awk, so your output may not come out in the same order as your input.
If you want your output to be delimited using vertical bars, change the -vOFS=, to -vOFS='|'.
Then you can sort using:
awk ... | sort
which defaults to -k1.