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Changing second column in csv conditionally

Help using Awk to change a fileSearch csv file columnPrinting pattern of “C” characterHow can I count lines of differently named files, and write the outcome to a csv file?Create csv from inconsistent text fileSum column 2 of .csv file if column 1 is the sameSearching for data from file1 in file2view the column names for CSV file?Delete multiple rows in csv fileMove specific column from csv file in front (select column by name)

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;

5

I have a csv file that looks like:

data/train/4/36280.png,four
data/train/2/10317.png,two
data/train/2/57890.png,two
data/train/1/53448.png,one
data/train/8/58233.png,eight
data/train/4/23599.png,four
data/train/2/35051.png,two
data/train/1/12323.png,one
data/train/9/18562.png,nine
data/train/8/46629.png,eight
data/train/7/1746.png,seven

Where first column is path and second is class. I would like to change the second column conditionally. In pseudo code I want something like:

If second column "four" change it to the next row's class

So far I've tried just to see if I can change ne class to another, but without success:

awk ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv

gives me the same csv.

Basically I would like a script that gives me following output csv:

data/train/4/36280.png,seven
data/train/2/10317.png,four
data/train/2/57890.png,two
data/train/1/53448.png,two
data/train/8/58233.png,one
data/train/4/23599.png,eight
data/train/2/35051.png,four
data/train/1/12323.png,two
data/train/9/18562.png,one
data/train/8/46629.png,nine
data/train/7/1746.png,eight

command-line text-processing awk csv

share|improve this question

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The default field separator in awk is whitespace; if you have comma separated data, you will need to set the separator accordingly - either with the -F command line option, or by setting FS="," in a BEGIN rule.
  
  – steeldriver
  Apr 5 at 7:00
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is "the next rows class" ? Could you please edit your question and add an example output?
  
  – RoVo
  Apr 5 at 7:17
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You mean like `awk FS="," ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv´ Next row class for line 1 is line 2, column 2. I basically want to shuffle the class in an easy way
  
  – iKnowItAll
  Apr 5 at 7:24
  

  
  
  
  

add a comment | 

5

I have a csv file that looks like:

data/train/4/36280.png,four
data/train/2/10317.png,two
data/train/2/57890.png,two
data/train/1/53448.png,one
data/train/8/58233.png,eight
data/train/4/23599.png,four
data/train/2/35051.png,two
data/train/1/12323.png,one
data/train/9/18562.png,nine
data/train/8/46629.png,eight
data/train/7/1746.png,seven

Where first column is path and second is class. I would like to change the second column conditionally. In pseudo code I want something like:

If second column "four" change it to the next row's class

So far I've tried just to see if I can change ne class to another, but without success:

awk ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv

gives me the same csv.

Basically I would like a script that gives me following output csv:

data/train/4/36280.png,seven
data/train/2/10317.png,four
data/train/2/57890.png,two
data/train/1/53448.png,two
data/train/8/58233.png,one
data/train/4/23599.png,eight
data/train/2/35051.png,four
data/train/1/12323.png,two
data/train/9/18562.png,one
data/train/8/46629.png,nine
data/train/7/1746.png,eight

command-line text-processing awk csv

share|improve this question

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  The default field separator in awk is whitespace; if you have comma separated data, you will need to set the separator accordingly - either with the -F command line option, or by setting FS="," in a BEGIN rule.
  
  – steeldriver
  Apr 5 at 7:00
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  What is "the next rows class" ? Could you please edit your question and add an example output?
  
  – RoVo
  Apr 5 at 7:17
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  You mean like `awk FS="," ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv´ Next row class for line 1 is line 2, column 2. I basically want to shuffle the class in an easy way
  
  – iKnowItAll
  Apr 5 at 7:24
  

  
  
  
  

add a comment | 

I have a csv file that looks like:

data/train/4/36280.png,four
data/train/2/10317.png,two
data/train/2/57890.png,two
data/train/1/53448.png,one
data/train/8/58233.png,eight
data/train/4/23599.png,four
data/train/2/35051.png,two
data/train/1/12323.png,one
data/train/9/18562.png,nine
data/train/8/46629.png,eight
data/train/7/1746.png,seven

Where first column is path and second is class. I would like to change the second column conditionally. In pseudo code I want something like:

If second column "four" change it to the next row's class

So far I've tried just to see if I can change ne class to another, but without success:

awk ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv

gives me the same csv.

Basically I would like a script that gives me following output csv:

data/train/4/36280.png,seven
data/train/2/10317.png,four
data/train/2/57890.png,two
data/train/1/53448.png,two
data/train/8/58233.png,one
data/train/4/23599.png,eight
data/train/2/35051.png,four
data/train/1/12323.png,two
data/train/9/18562.png,one
data/train/8/46629.png,nine
data/train/7/1746.png,eight

command-line text-processing awk csv

share|improve this question

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

data/train/4/36280.png,four
data/train/2/10317.png,two
data/train/2/57890.png,two
data/train/1/53448.png,one
data/train/8/58233.png,eight
data/train/4/23599.png,four
data/train/2/35051.png,two
data/train/1/12323.png,one
data/train/9/18562.png,nine
data/train/8/46629.png,eight
data/train/7/1746.png,seven

If second column "four" change it to the next row's class

awk ' if ($2 == "zero") $2="one"; print $0 ' train.csv > new_file.csv

data/train/4/36280.png,seven
data/train/2/10317.png,four
data/train/2/57890.png,two
data/train/1/53448.png,two
data/train/8/58233.png,one
data/train/4/23599.png,eight
data/train/2/35051.png,four
data/train/1/12323.png,two
data/train/9/18562.png,one
data/train/8/46629.png,nine
data/train/7/1746.png,eight

share|improve this question

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 2 days ago

Zanna

51.3k13140243

edited 2 days ago

Zanna

51.3k13140243

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

New contributor

iKnowItAll is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked Apr 5 at 6:55

iKnowItAlliKnowItAll

283

1 Answer
1

active

oldest

votes

5

bash solution:

readarray -t filename < <(cut -d ',' -f1 train.csv)
readarray -t class < <(cut -d ',' -f2 train.csv)

for (( i=0; i<$#filename[@]; i++ )); do
 printf '%s,%sn' "$filename[$i]" "$class[$((i-1))]";
done > new_file.csv

---

Equivalent awk solution:

awk -F, '
 
 filename[NR]=$1
 class[NR]=$2
 
 END 
 OFS=","
 print filename[1],class[NR]
 for (i=2;i<=NR;i++) 
 print filename[i],class[i-1]
 
 
' train.csv > new_file.csv

Both solutions first read the lines into arrays filename and class. Only difference is that the bash array starts with 0, the awk array with 1.

Then, we loop over the arrays and print the desired output. In the awk solution, we need to treat the first line separately as, unlike in bash, array[-1] does not return the last element.

The awk solution is a bit faster.

share|improve this answer

edited Apr 5 at 8:09

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I tried it and it looks great! Could I ask how I would save this to a new CSV? I guess its putting > new_file.csv at the end maybe?
  
  – iKnowItAll
  Apr 5 at 7:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  exactly, added to the answer
  
  – RoVo
  Apr 5 at 7:44
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks alot!! Works great!
  
  – iKnowItAll
  Apr 5 at 7:45
  

  
  
  
  

add a comment | 

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5

bash solution:

readarray -t filename < <(cut -d ',' -f1 train.csv)
readarray -t class < <(cut -d ',' -f2 train.csv)

for (( i=0; i<$#filename[@]; i++ )); do
 printf '%s,%sn' "$filename[$i]" "$class[$((i-1))]";
done > new_file.csv

---

Equivalent awk solution:

awk -F, '
 
 filename[NR]=$1
 class[NR]=$2
 
 END 
 OFS=","
 print filename[1],class[NR]
 for (i=2;i<=NR;i++) 
 print filename[i],class[i-1]
 
 
' train.csv > new_file.csv

Both solutions first read the lines into arrays filename and class. Only difference is that the bash array starts with 0, the awk array with 1.

Then, we loop over the arrays and print the desired output. In the awk solution, we need to treat the first line separately as, unlike in bash, array[-1] does not return the last element.

The awk solution is a bit faster.

share|improve this answer

edited Apr 5 at 8:09

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I tried it and it looks great! Could I ask how I would save this to a new CSV? I guess its putting > new_file.csv at the end maybe?
  
  – iKnowItAll
  Apr 5 at 7:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  exactly, added to the answer
  
  – RoVo
  Apr 5 at 7:44
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks alot!! Works great!
  
  – iKnowItAll
  Apr 5 at 7:45
  

  
  
  
  

add a comment | 

5

bash solution:

readarray -t filename < <(cut -d ',' -f1 train.csv)
readarray -t class < <(cut -d ',' -f2 train.csv)

for (( i=0; i<$#filename[@]; i++ )); do
 printf '%s,%sn' "$filename[$i]" "$class[$((i-1))]";
done > new_file.csv

---

Equivalent awk solution:

awk -F, '
 
 filename[NR]=$1
 class[NR]=$2
 
 END 
 OFS=","
 print filename[1],class[NR]
 for (i=2;i<=NR;i++) 
 print filename[i],class[i-1]
 
 
' train.csv > new_file.csv

Both solutions first read the lines into arrays filename and class. Only difference is that the bash array starts with 0, the awk array with 1.

Then, we loop over the arrays and print the desired output. In the awk solution, we need to treat the first line separately as, unlike in bash, array[-1] does not return the last element.

The awk solution is a bit faster.

share|improve this answer

edited Apr 5 at 8:09

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  I tried it and it looks great! Could I ask how I would save this to a new CSV? I guess its putting > new_file.csv at the end maybe?
  
  – iKnowItAll
  Apr 5 at 7:43
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  exactly, added to the answer
  
  – RoVo
  Apr 5 at 7:44
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks alot!! Works great!
  
  – iKnowItAll
  Apr 5 at 7:45
  

  
  
  
  

add a comment | 

bash solution:

readarray -t filename < <(cut -d ',' -f1 train.csv)
readarray -t class < <(cut -d ',' -f2 train.csv)

for (( i=0; i<$#filename[@]; i++ )); do
 printf '%s,%sn' "$filename[$i]" "$class[$((i-1))]";
done > new_file.csv

---

Equivalent awk solution:

awk -F, '
 
 filename[NR]=$1
 class[NR]=$2
 
 END 
 OFS=","
 print filename[1],class[NR]
 for (i=2;i<=NR;i++) 
 print filename[i],class[i-1]
 
 
' train.csv > new_file.csv

Both solutions first read the lines into arrays filename and class. Only difference is that the bash array starts with 0, the awk array with 1.

Then, we loop over the arrays and print the desired output. In the awk solution, we need to treat the first line separately as, unlike in bash, array[-1] does not return the last element.

The awk solution is a bit faster.

share|improve this answer

edited Apr 5 at 8:09

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

readarray -t filename < <(cut -d ',' -f1 train.csv)
readarray -t class < <(cut -d ',' -f2 train.csv)

for (( i=0; i<$#filename[@]; i++ )); do
 printf '%s,%sn' "$filename[$i]" "$class[$((i-1))]";
done > new_file.csv

awk -F, '
 
 filename[NR]=$1
 class[NR]=$2
 
 END 
 OFS=","
 print filename[1],class[NR]
 for (i=2;i<=NR;i++) 
 print filename[i],class[i-1]
 
 
' train.csv > new_file.csv

share|improve this answer

edited Apr 5 at 8:09

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

answered Apr 5 at 7:39

RoVoRoVo

8,1701943

answered Apr 5 at 7:39

RoVoRoVo

8,1701943