How to add data beside each other in a csv file - linux

Question

If I have 3 csv files, and I want to merge the data all into one, but beside each other, how would I do it? For example:
Initial Merged file:
,,,,,,,,,,,,
File 1:
20,09/05,5694
20,09/06,3234
20,09/08,2342
File 2:
20,09/05,2341
20,09/06,2334
20,09/09,342
File 3:
20,09/05,1231
20,09/08,3452
20,09/10,2345
20,09/11,372
Final merged File:
09/05,5694,,,09/05,2341,,,09/05,1231
09/06,3234,,,09/06,2334,,,09/08,3452
09/08,2342,,,09/09,342,,,09/10,2345
,,,,,,,,09/11,372
Basically data from each file goes into a specific column of the merged file.
I know the awk function can be used for this, but I have no clue how to start
EDIT: Only the 2nd and 3rd Columns of each file are being printed. I was using this to print out the 2nd and 3rd columns:
awk -v f="${i}" -F, 'match ($0,f) { print $2","$3 }' file3.csv > d$i.csv
however, say for example, file1 and file2 were null in that row, the data for that row would be shifted to the left. so I came up with this to account for the shift:
awk -v x="${i}" -F, 'match ($0,x) { if ($2='/NULL') { print "," }; else { print $2","$3}; }' alld.csv > d$i.csv

Answer 1

Using GNU awk for ARGIND:
$ gawk '{ a[FNR,ARGIND]=$0; maxFnr=(FNR>maxFnr?FNR:maxFnr) }
END {
for (i=1;i<=maxFnr;i++) {
for (j=1;j<ARGC;j++)
printf "%s%s", (j==1?"":",,,"), (a[i,j]?a[i,j]:",")
print ""
}
}
' file1 file2 file3
09/05,5694,,,09/05,2341,,,09/05,1231
09/06,3234,,,09/06,2334,,,09/08,3452
09/08,2342,,,09/09,342,,,09/10,2345
,,,,,,,,09/11,372
If you don't have GNU awk, just add an initial line that says FNR==1{ARGIND++}.
Commented version per request:
$ gawk '
{ a[FNR,ARGIND]=$0; # Store the current line in a 2-D array `a` indexed by
# the current line number `FNR` and file number `ARGIND`.
maxFnr=(FNR>maxFnr?FNR:maxFnr) # save the max FNR value
}
END{
for (i=1;i<=maxFnr;i++) { # Loop from 1 to max number of fields
# seen across all files and for each:
for (j=1;j<ARGC;j++) # Loop from 1 to total number of files parsed and:
printf "%s%s", # Print 2 strings, specifically:
(j==1?"":",,,"), # A field separator - empty if were printing
# the first field, three commas otherwise.
(a[i,j]?a[i,j]:",") # The value stored in the array if it was
# present in the files, a comma otherwise.
print "" # Print a newline
}
}
' file1 file2 file3
I originally was using an array fnr[FNR] to track the max value of FNR but IMHO that's kinda obscure and it has a flaw where if no lines have, say, a 2nd field then a loop on for (i=1;i in fnr;i++) in the END section would bail out before getting to the 3rd field.

Answer 2

paste is done for this:
$ paste -d";" f1 f2 f3 | sed 's/;/,,,/g'
09/05,5694,,,09/05,2341,,,09/05,1231
09/06,3234,,,09/06,2334,,,09/08,3452
09/08,2342,,,09/09,342,,,09/10,2345
,,,,,,09/11,372
Note that the paste alone will output just one comma:
$ paste -d, f1 f2 f3
09/05,5694,09/05,2341,09/05,1231
09/06,3234,09/06,2334,09/08,3452
09/08,2342,09/09,342,09/10,2345
,,09/11,372
So to have multiple ones we can use another delimiter like ; and then replace by ,,, with sed:
$ paste -d";" f1 f2 f3 | sed 's/;/,,,/g'
09/05,5694,,,09/05,2341,,,09/05,1231
09/06,3234,,,09/06,2334,,,09/08,3452
09/08,2342,,,09/09,342,,,09/10,2345
,,,,,,09/11,372

Answer 3

Using pr:
$ pr -mts',,,' file[1-3]
09/05,5694,,,09/05,2341,,,09/05,1231
09/06,3234,,,09/06,2334,,,09/08,3452
09/08,2342,,,09/09,342,,,09/10,2345
,,,,,,09/11,372