I have a .csv where each row corresponds to a person (first column) and attributes with values that are available for that person. I want to extract the names and values a particular attribute for persons where the attribute is available. The doc is structured as follows:
name,attribute1,value1,attribute2,value2,attribute3,value3
joe,height,5.2,weight,178,hair,
james,,,,,,
jesse,weight,165,height,5.3,hair,brown
jerome,hair,black,breakfast,donuts,height,6.8
I want a file that looks like this:
name,attribute,value
joe,height,5.2
jesse,height,5.3
jerome,height,6.8
Using this earlier post, I've tried a few different awk methods but am still having trouble getting both the first column and then whatever column has the desired value for the attribute (say height). For example the following returns everything.
awk -F "height," '{print $1 "," FS$2}' file.csv
I could grep only the rows with height in them, but I'd prefer to do everything in a single line if I can.
You may use this awk:
cat attrib.awk
BEGIN {
FS=OFS=","
print "name,attribute,value"
}
NR > 1 && match($0, k "[^,]+") {
print $1, substr($0, RSTART+1, RLENGTH-1)
}
# then run it as
awk -v k=',height,' -f attrib.awk file
name,attribute,value
joe,height,5.2
jesse,height,5.3
jerome,height,6.8
# or this one
awk -v k=',weight,' -f attrib.awk file
name,attribute,value
joe,weight,178
jesse,weight,165
With your shown samples please try following awk code. Written and tested in GNU awk. Simple explanation would be, using GNU awk and setting RS(record separator) to ^[^,]*,height,[^,]* and then printing RT as per requirement to get expected output.
awk -v RS='^[^,]*,height,[^,]*' 'RT{print RT}' Input_file
I'd suggest a sed one-liner:
sed -n 's/^\([^,]*\).*\(,height,[^,]*\).*/\1\2/p' file.csv
One awk idea:
awk -v attr="height" '
BEGIN { FS=OFS="," }
FNR==1 { print "name", "attribute", "value"; next }
{ for (i=2;i<=NF;i+=2) # loop through even-numbered fields
if ($i == attr) { # if field value is an exact match to the "attr" variable then ...
print $1,$i,$(i+1) # print current name, current field and next field to stdout
next # no need to check rest of current line; skip to next input line
}
}
' file.csv
NOTE: this assumes the input value (height in this example) will match exactly (including same capitalization) with a field in the file
This generates:
name,attribute,value
joe,height,5.2
jesse,height,5.3
jerome,height,6.8
With a perl one-liner:
$ perl -lne '
print "name,attribute,value" if $.==1;
print "$1,$2" if /^(\w+).*(height,\d+\.\d+)/
' file
output
name,attribute,value
joe,height,5.2
jesse,height,5.3
jerome,height,6.8
awk accepts variable-value arguments following a -v flag before the script. Thus, the name of the required attribute can be passed into an awk script using the general pattern:
awk -v attr=attribute1 ' {} ' file.csv
Inside the script, the value of the passed variable is reference by the variable name, in this case attr.
Your criteria are to print column 1, the first column containing the name, the column corresponding to the required header value, and the column immediately after that column (holding the matched values).
Thus, the following script allows you to fish out the column headed "attribute1" and it's next neighbour:
awk -v attr=attribute1 ' BEGIN {FS=","} /attr/{for (i=1;i<=NF;i++) if($i == attr) col=i;} {print $1","$col","$(col+1)} ' data.txt
result:
name,attribute1,value1
joe,height,5.2
james,,
jesse,weight,165
jerome,hair,black
another column (attribute 3):
awk -v attr=attribute3 ' BEGIN {FS=","} /attr/{for (i=1;i<=NF;i++) if($i == attr) col=i;} {print $1","$col","$(col+1)} ' awkNames.txt
result:
name,attribute3,value3
joe,hair,
james,,
jesse,hair,brown
jerome,height,6.8
Just change the value of the -v attr= argument for the required column.
I'm trying to modify a groups.tsv file (I'm on repl.it so path to file is fine).
Each line in the file looks like this:
groupname \t amountofpeople \t lastadded
and I'm trying to count the occurences of both groupname($nomgrp) and a login($login), and change lastadded to login.
varcol2=$(grep "$nomgrp" groups | cut "-d " -f2- | awk -F"\t" '{print $2}' )
((varcol21=varcol2+1));
varcol3=$(awk -F"\t" '{print $3}' groups)
sed -i "s|${nomgrp}\t${varcol2}\t$varcol3|${nomgrp}\t${varcol21}\t${login}|" groups
However, I'm getting the error message:
sed : -e expression #1, char 27: unterminated 's' command
The groups file has lines such as " sudo 2 user1" (delimited with a tab): a user inputs "user" which is stored in $login, then "sudo" which is stored in $nomgrp.
What am I doing wrong?
Sorry if this has been answered/super easy to fix, I'm quite the newbie here...
If I understand what you are trying to do correctly and if you have GNU awk, you could do
gawk -i inplace -F '\t' -v group="$nomgrp" -v login="$login" -v OFS='\t' '$1 == group { $2 = $2 + 1; $3 = login; } { print }' groups.tsv
Example:
$ cat groups.tsv
wheel 1000 2019-12-10
staff 1234 2019-12-11
users 9001 2019-12-12
$ gawk -i inplace -F '\t' -v group=wheel -v login=2019-12-12 -v OFS='\t' '$1 == group { $2 = $2 + 1; $3 = login; } 1' groups.tsv
$ cat groups.tsv
wheel 1001 2019-12-12
staff 1234 2019-12-11
users 9001 2019-12-12
This works as follows:
-i inplace is a GNU awk extension that allows you to change a file in place,
-F '\t' sets the input field separator to a tab so that the input is interpreted as TSV and fields with spaces in them are not split apart,
-v variable=name sets an awk variable for use in awk's code,
specifically, -v OFS='\t' sets the output field separator variable to a tab, so that the output is again a TSV
So we set variables group, login to your shell variables and ensure that awk outputs a TSV. The code then works as follows:
$1 == group { # If the first field in a line is equal to the group variable
$2 = $2 + 1; # add 1 to the second field
$3 = login; # and overwrite the third with the login variable
}
{ # in all lines:
print # print
}
{ print } could also be abbreviated as 1, I'm sure people someone will point out, but I find this way easier to explain.
If you do not have GNU awk, you could achieve the same with a temporary file, e.g.
awk -F '\t' -v group="$nomgrp" -v login="$login" -v OFS='\t' '$1 == group { $2 = $2 + 1; $3 = login; } { print }' groups.tsv > groups.tsv.new
mv groups.tsv.new groups.tsv
I have a file that has multiple lines that starts with a keyword. I only want to modify one of them and it's easy to distinguish the two. I want the one that is under the [dbinfo] section. The domain name is static so I know that won't change.
awk -F '=' '$1 ~ /^dbhost/ {print $NF};' myfile.txt
myfile.txt
[ual]
path=/web/
dbhost=ez098sf
[dbinfo]
dbhost=ec0001.us-east-1.localdomain
dbname=ez098sf_default
dbpass=XXXXXX
You can use this awk command to first check for presence of [dbinfo] section and then modify dbhost parameter:
awk -v h='newhost' 'BEGIN{FS=OFS="="}
$0 == "[dbinfo]" {sec=1} sec && $1 == "dbhost"{$2 = h; sec=0} 1' file
[ual]
path=/web/
dbhost=ez098sf
[dbinfo]
dbhost=newhost
dbname=ez098sf_default
dbpass=XXXXXX
You want to utilize a little bit of a state machine here:
awk -F '=' '
$0 ~ /^\[.*\]/ {in_db_info=($0=="[dbinfo]"}
$0 ~ /^dbhost/{if (in_db_info) print $2;}' myfile.txt
You can also do it with sed:
sed '/\[dbinfo\]/,/\[/s/\(^dbhost=\).*/\1domain.com/' myfile.txt
I'm trying to take last value in third column of a CSV file and replace then the whole third column with this value.
I've been trying this:
var=$(tail -n 1 math_ready.csv | awk -F"," '{print $3}'); awk -F, '{$3="$var";}1' OFS=, math_ready.csv > math1.csv
But it's not working and I don't understand why...
Please help!
awk '
BEGIN { ARGV[2]=ARGV[1]; ARGC++; FS=OFS="," }
NR==FNR { last = $3; next }
{ $3 = last; print }
' math_ready.csv > math1.csv
The main problem with your script was trying to access a shell variable ($var) inside your awk script. Awk is not shell, it is a completely separate language/tool with it's own namespace and variables. You cannot directly access a shell variable in awk, just like you couldn't access it in C. To access the VALUE of a shell variable you'd do:
shellvar=27
awk -v awkvar="$shellvar" 'BEGIN{ print awkvar }'`
Some additional cleanup:
When FS and OFS have the same value, don't assign them each to that value separately, use BEGIN{ FS=OFS="," } instead for clarity and maintainability.
Do not iniatailize variables AFTER the script that uses those variables unless you have a very specifc reason to do so. Use awk -F... -v OFS=... 'script' to init those variables to separate values, not awk -F... 'script' OFS=... as it's very unnatural to init variables in the code segment AFTER you've used them and variables inited in the args list at the end are not initialized when the BEGIN section is executed which can cause bugs.
A shell variable is not expandable internally in awk. You can do this instead:
awk -F, -v var="$var" '{ $3 = var } 1' OFS=, math_ready.csv > math1.cs
And you probably can simplify your code with this:
awk -F, 'NR == FNR { r = $3; next } { $3 = r } 1' OFS=, math_ready.csv math_ready.csv > math1.csv
Example input:
1,2,1
1,2,2
1,2,3
1,2,4
1,2,5
Output:
1,2,5
1,2,5
1,2,5
1,2,5
1,2,5
Try this one liner. It doesn't depend on the column count
var=`tail -1 sample.csv | perl -ne 'm/([^,]+)$/; print "$1";'`; cat sample.csv | while read line; do echo $line | perl -ne "s/[^,]*$/$var\n/; print $_;"; done
cat sample.csv
24,1,2,30,12
33,4,5,61,3333
66,7,8,91111,1
76,10,11,32,678
Out:
24,1,2,30,678
33,4,5,61,678
66,7,8,91111,678
76,10,11,32,678