Merge rows with same value and every 100 lines in csv file using command - shell

Question

I have a csv file like below:
http://www.a.com/1,apple
http://www.a.com/2,apple
http://www.a.com/3,apple
http://www.a.com/4,apple
...
http://www.z.com/1,flower
http://www.z.com/2,flower
http://www.z.com/3,flower
...
I want combine the csv file to new csv file like below:
"http://www.a.com/1
http://www.a.com/2
http://www.a.com/3
http://www.a.com/4
",apple
"http://www.z.com/1
http://www.z.com/2
http://www.z.com/3
http://www.z.com/4
...
http://www.z.com/100
",flower
"http://www.z.com/101
http://www.z.com/102
http://www.z.com/103
http://www.z.com/104
...
http://www.z.com/200
",flower
I want keep the first column every cell have max 100 lines http url.
Column two same value will appear in corresponding cell.
Is there a very simple command pattern to achieve this idea ？
I used command below:
awk '{if(NR%100!=0)ORS="\t";else ORS="\n"}1' test.csv > result.csv

Answer 1

$ awk -F, '$2!=p || n==100 {if(NR!=1) print "\"," p; printf "\""; p=$2; n=0}
{print $1; n+=1} END {print "\"," p}' test.csv
"http://www.a.com/1
http://www.a.com/2
http://www.a.com/3
http://www.a.com/4
",apple
"http://www.z.com/1
http://www.z.com/2
http://www.z.com/3
",flower
First set the field separator to the comma (-F,). Then:
If the second field changes ($2!=p) or if we already printed 100 lines in the current batch (n==100):
if it is not the first line, print a double quote, a comma, the previous second field and a newline,
print a double quote,
store the new second field in variable p for later comparisons,
reset line counter n.
For all lines print the first field and increment line counter n.
At the end print a double quote, a comma and the last value of second field.

Answer 2

1st solution: With your shown samples, please try following awk code.
awk '
BEGIN{
s1="\""
FS=OFS=","
}
prev!=$2 && prev{
print s1 val s1,prev
val=""
}
{
val=(val?val ORS:"")$1
prev=$2
}
END{
if(val){
print s1 val s1,prev
}
}
' Input_file
2nd solution: In case your Input_file is NOT sorted with 2nd column then try following sort + awk code.
sort -t, -k2 Input_file |
awk '
BEGIN{
s1="\""
FS=OFS=","
}
prev!=$2 && prev{
print s1 val s1,prev
val=""
}
{
val=(val?val ORS:"")$1
prev=$2
}
END{
if(val){
print s1 val s1,prev
}
}
'
Output will be as follows:
"http://www.a.com/1
http://www.a.com/2
http://www.a.com/3
http://www.a.com/4",apple
"http://www.z.com/1
http://www.z.com/2
http://www.z.com/3",flower

Answer 3

Given:
cat file
http://www.a.com/1,apple
http://www.a.com/2,apple
http://www.a.com/3,apple
http://www.a.com/4,apple
http://www.z.com/1,flower
http://www.z.com/2,flower
http://www.z.com/3,flower
Here is a two pass awk to do this:
awk -F, 'FNR==NR{seen[$2]=FNR; next}
seen[$2]==FNR{
printf("\"%s%s\"\n,%s\n",data,$1,$2)
data=""
next
}
{data=data sprintf("%s\n",$1)}' file file
If you want to print either at the change of the $2 value or at some fixed line interval (like 100) you can do:
awk -F, -v n=100 'FNR==NR{seen[$2]=FNR; next}
seen[$2]==FNR || FNR%n==0{
printf("\"%s%s\"\n,%s\n",data,$1,$2)
data=""
next
}
{data=data sprintf("%s\n",$1)}' file file
Either prints:
"http://www.a.com/1
http://www.a.com/2
http://www.a.com/3
http://www.a.com/4"
,apple
"http://www.z.com/1
http://www.z.com/2
http://www.z.com/3"
,flower