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Old 06-30-2017, 04:29 AM   #1
DavinaP
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Wink help with extracting entries from a multiple entry columns in a file


Hi All,
I have a tab separated file where the entries from the 2nd column onwards are multiple and separated by a ;.
I would like to get only the 1st entry of each column. I have 8000+ columns and not giving all here.
Here is a sample:

rs1
AG;0.79780;0.132;0.204;487;923
GG;0.79780;0.115;0.161;213;457
AG;0.79780;0.095;0.152;375;835

I would like to have

rs1
AG
GG
AG

Appreciate any help.
Thank you,
Davina

Last edited by DavinaP; 06-30-2017 at 04:36 AM.
 
Old 06-30-2017, 04:39 AM   #2
syg00
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Trivial in awk - nominate ";" as field separator.
 
Old 06-30-2017, 04:40 AM   #3
Turbocapitalist
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That should be pretty easy with awk or perl, and there are several ways to approach the problem in either. Which one are you trying and can you show how far you have gotten?
 
Old 06-30-2017, 04:43 AM   #4
Turbocapitalist
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Quote:
Originally Posted by syg00 View Post
Trivial in awk - nominate ";" as field separator.
The sample above has only one column. The other columns are apparently separated by tabs.

So I'd keep tabs as the separator, but use gsub() to zap everything starting with the first semicolon in each field. But is there a way to do that or otherwise get the same result without needing a loop to go through the fields in each row?
 
Old 06-30-2017, 04:45 AM   #5
DavinaP
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Quote:
Originally Posted by Turbocapitalist View Post
That should be pretty easy with awk or perl, and there are several ways to approach the problem in either. Which one are you trying and can you show how far you have gotten?
Thanks, I have not gotten anywhere much except trying this command:
tr -s '; ' '\t' < "file name".
However that splits each column into multiple columns at the points where ; occurs.
I just want the first entries of each column (remember I have thousands of columns).

Last edited by DavinaP; 06-30-2017 at 04:46 AM.
 
Old 06-30-2017, 04:51 AM   #6
syg00
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Oops - didn't read that too well did I. Sorry about that. I'll be back.
 
Old 06-30-2017, 04:52 AM   #7
Turbocapitalist
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Ok. Try escalating to awk then. Be sure to see the manual page.

Code:
man awk
But that is a reference (actually the reference) only and though you should use it a lot, it might not be the best place to start with awk. So also see this site:

http://www.grymoire.com/Unix/Awk.html

It is a very thorough introduction.
 
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Old 06-30-2017, 05:45 AM   #8
syg00
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Quote:
Originally Posted by Turbocapitalist View Post
So I'd keep tabs as the separator, but use gsub() to zap everything starting with the first semicolon in each field. But is there a way to do that or otherwise get the same result without needing a loop to go through the fields in each row?
gensub maybe - that way you can use back-references.
Personally I'd use sed - same/similar regex.
 
Old 06-30-2017, 06:31 AM   #9
syg00
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How's your regex fu Davina ?.
Your data (for this discussion) can be defined as "a bunch of non-semicolon characters (that you want to keep), followed by a bunch of non-whitespace characters (that you want to remove)". Define that in regex, and make the substitution global.
 
Old 07-01-2017, 12:41 AM   #10
Turbocapitalist
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Quote:
Originally Posted by syg00 View Post
Personally I'd use sed - same/similar regex.
Yes. If one thinks about the lines as a single unit, then sed is a good idea. I had been thinking about the line as a record with fields and thus gravitated to awk. Either will work. The language sed is a little terse while awk is a little more complicated, though.

DavinaP, the substitution command in sed is what to look at:

Code:
sed -e 's/old/new/g;' < oldfile.txt > newfile.txt
The greater than > and less than < signs are IO redirects in the shell.
 
Old 07-01-2017, 07:40 AM   #11
BW-userx
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I do not use awk but try this,
Code:
userx%slackwhere ⚡ testDIR ⚡> awk -F\;  '{print $1}' fileDirLit
rs1
AG
GG
AG
http://cs.canisius.edu/ONLINESTUFF/P...K/awk.examples

or to keep it handy
Code:
userx%slackwhere ⚡ testDIR ⚡> awk -F\;  '{print $1}' fileDirLit > results       
userx%slackwhere ⚡ testDIR ⚡> cat results
rs1
AG
GG
AG
to skip that first line
Code:
userx%slackwhere ⚡ testDIR ⚡> awk -F\; 'NR > 1 {print $1}' fileDirLit 
AG
GG
AG
GG
AG

Last edited by BW-userx; 07-01-2017 at 08:07 AM.
 
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Old 07-01-2017, 01:02 PM   #12
AwesomeMachine
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You can use:
Code:
$ tr ';' \t < file > file2
cat file2 | awk '{print $1}' > file3
That is untested, but I think it will work. What you're doing is changing the semicolons to tabs, which are white space, and then selecting the column before the first white space.
 
Old 07-03-2017, 08:05 AM   #13
allend
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My feeling is that the example given has been confusing.
If the data format is tab separated columns with semicolon delimiters within columns, such as
Code:
AG;0.79780;0.132;0.204;487;923	AG;0.79780;0.132;0.204;487;923	AG;0.79780;0.132;0.204;487;923
GG;0.79780;0.115;0.161;213;457	GG;0.79780;0.115;0.161;213;457	GG;0.79780;0.115;0.161;213;457
AG;0.79780;0.095;0.152;375;835	AG;0.79780;0.095;0.152;375;835	AG;0.79780;0.095;0.152;375;835
then I suggest using awk
Code:
 awk -F ";[^\t]+" '{for (i=1;i<NF;i++){printf"%s", $i}; printf"\n"}' <inputfile>

Last edited by allend; 07-03-2017 at 08:14 AM.
 
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Old 07-03-2017, 08:11 AM   #14
BW-userx
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in OP post he says all he wants is the very first column which is all of the AG GG AG etc..
which this actually gives him
Code:
awk -F\;  '{print $1}' fileToLooKAt > results

Last edited by BW-userx; 07-03-2017 at 08:12 AM.
 
Old 07-03-2017, 10:32 AM   #15
AwesomeMachine
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But the OP doesn't show any tabs, so $1 is the whole row.

Sorry, didn't see the "-F".

Last edited by AwesomeMachine; 07-03-2017 at 10:34 AM.
 
  


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