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How to repeat a character in a field if it's a single character?


 
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# 1  
How to repeat a character in a field if it's a single character?

I have a csv dataset like this :
Code:
C,rs18768
G,rs13785
GA,rs1065
G,rs1801279
T,rs9274407
A,rs730012

I'm thinking of use like awk, sed to covert the dataset to this format: (if it's two character, then keep the same)
Code:
CC,rs18768
GG,rs13785
GA,rs1065
GG,rs1801279
TT,rs9274407
AA,rs730012

Could anyone give me some clues ?

Last edited by RavinderSingh13; 04-28-2019 at 02:11 AM..
# 2  
Hello nengcheng,

It is always recommended to add your efforts in your post which you have out in order to solve your own problem, could you please try following.

Code:
awk 'BEGIN{FS=OFS=","} length($1)==1{sub(/.*/,"&&",$1)} 1 '  Input_file

Output will be as follows.
Code:
CC,rs18768
GG,rs13785
GA,rs1065
GG,rs1801279
TT,rs9274407
AA,rs730012


2nd solution: Using $1 value itself to make it double.
Code:
awk 'BEGIN{FS=OFS=","} length($1)==1{$1=$1$1} 1'   Input_file

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
# 3  
Code:
sed 's/^\(.\),/\1&/'

These 2 Users Gave Thanks to nezabudka For This Post:
# 4  
Quote:
Originally Posted by nezabudka
Code:
sed 's/^\(.\),/\1&/'

Cool solution nez, how about a pure BASH one, just for fun Smilie

Code:
while IFS=, read field1 field2
do
  if [[ ${#field1} -eq 1 ]]
  then
      field1=${field1}${field1}
  fi
  echo "$field1,$field2"
done < "Input_file"

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
# 5  
Code:
#!/bin/bash
while read -n2 a; do
        read b
        echo ${a//,/$a}$b
done < file

--- Post updated at 10:37 ---

Code:
#!/bin/bash
while read a; do
        echo ${a/#?,/${a%,*}${a%,*},}
done < file


Last edited by nezabudka; 04-28-2019 at 05:00 AM..
This User Gave Thanks to nezabudka For This Post:
# 6  
Thank you Singh, I will try it next time.

--- Post updated at 03:55 AM ---

Thank you, nezabudka it also worked for me.
# 7  
Hi Ravinder...

Just by removing one set of [] makes your version fully POSIX compliant:
Code:
#!/usr/local/bin/dash

echo 'C,rs18768
G,rs13785
GA,rs1065
G,rs1801279
T,rs9274407
A,rs730012' > /tmp/text

while IFS=, read field1 field2
do
    if [ ${#field1} -eq 1 ]
     then
        field1=${field1}${field1}
    fi
    echo "$field1,$field2"
 done < /tmp/text

Results, OSX 10.14.3, default bash terminal, calling dash:
Code:
Last login: Sun Apr 28 11:31:12 on ttys000
AMIGA:amiga~> cd desktop/Code/Shell
AMIGA:amiga~/desktop/Code/Shell> ./add_single_char.sh
CC,rs18768
GG,rs13785
GA,rs1065
GG,rs1801279
TT,rs9274407
AA,rs730012
AMIGA:amiga~/desktop/Code/Shell> _

This User Gave Thanks to wisecracker For This Post:

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