i have a testfile.csv of which i want to replace all values in the third column with a new value without touching the header:
testfile.csv
col1,col2,col3
a,a,a
b,b,b
i tried this code below where i specified NR>1:
cat test_file.csv| awk -F"," 'NR>1{OFS=",";{$3="10/1/2015"} print}' >xx
my output gives me the below but it also edited the header of col3 which is not what i want:
xx
col1,col2,10/1/2015
a,a,10/1/2015
b,b,10/1/2015
i want this:
col1,col2,col3
a,a,10/1/2015
b,b,10/1/2015
Your script should skip the first line. So you should not even see col1,col2,col3. Please make sure that the first line of testfile.csv start with col1,col2,col3.
If you want to see also the first line you need to:
cat testfile.csv| awk -F"," '{ if (NR>1) {OFS=",";{$3="10/1/2015"} print} else print}'
I didn't get the same output as you
a,a,10/1/2015
b,b,10/1/2015
which is what I would have expected.
So the NR>1 worked for me.
Try
echo "col1,col2,col3
a,a,a
b,b,b" \
| awk -F"," -vOFS="," 'NR==1{print};NR>1{$3="10/1/2015"; print}'
output
col1,col2,col3
a a 10/1/2015
b b 10/1/2015
Also if you data has been created in MSWindows environment, and your are now processing in Linux, be sure to remove \r chars, with dos2unix myDataFile.txt
IHTH
Related
I have a bunch of big csv I want to prefix every header column with fixed string. There is more than 500 columns in every file.
suppose my header is:
number;date;customer;key;amount
I tried this awk line:
awk -F';' 'NR==1{gsub(/[^a-z_]/,"input_file.")} { print }'
but I get (note fist column is missing prefix and separator is removed):
numberinput_file.dateinput_file.customerinput_file.keyinput_file.amount
expected output:
input_file.number;input_file.date;input_file.customer;input_file.key;input_file.amount
In any awk that'd be:
$ awk 'NR==1{gsub(/^|;/,"&input_file.")} 1' file
input_file.number;input_file.date;input_file.customer;input_file.key;input_file.amount
but sed exists to do simple substitutions like that, e.g. using a sed that has -E to enable EREs (e.g. GNU and BSD sed):
$ sed -E '1s/^|;/&input_file./g' file
input_file.number;input_file.date;input_file.customer;input_file.key;input_file.amount
If you're using GNU tools then you could use either of the above to change all of your CSV files at once with either of these:
awk -i inplace 'NR==1{gsub(/^|;/,"&input_file.")} 1' *.csv
sed -i -E '1s/^|;/&input_file./g' *.csv
Your gsub would brutally replace any nonalphabetic character anywhere in the input with the prefix - including your column separators.
The print can be abbreviated to the common idiom 1 at the very end of your script; this simply means "this condition is true; perform the default action for every line (i.e. print it all)" though this is just a stylistic change.
awk -F';' 'NR==1{
sub(/^/, "input_file."); gsub(/;/, ";input_file."); }
1' filename
If you want to perform this on multiple files, probably put a shell loop around it. If you only want to concatenate everything to standard output, you can give all the files to Awk in one go (in which case you probably don't want to print the header line for any file after the first; maybe change the 1 to NR==1 || FNR != 1).
I would use GNU AWK following way, let file.txt content be
number;date;customer;key;amount
1;2;3;4;5
6;7;8;9;10
then
awk 'BEGIN{FS=";";OFS=";input_file."}NR==1{$1="input_file." $1}{print}' file.txt
output
input_file.number;input_file.date;input_file.customer;input_file.key;input_file.amount
1;2;3;4;5
6;7;8;9;10
Explanation: I set OFS to ; followed by prefix. Then in first line I add prefix to first column, which trigger string rebuilding. No modification is done in any other line, thus they are printed as is.
(tested in GNU Awk 5.0.1)
Also with awk using for loop and printf:
awk 'BEGIN{FS=OFS=";"} NR==1{for (i=1; i<=NF; i++) printf "%s%s", "input_file." $i, (i<NF ? OFS : ORS)}' file
input_file.number;input_file.date;input_file.customer;input_file.key;input_file.amount
I have a csv file with thousands of lines in it. I'd like to be able to find values that only appear once in this file.
For instance
dog
dog
cat
dog
bird
I'd like to get as my result:
cat
bird
I tried using the following awk command but it returned one of each value in the file:
awk -F"," '{print $1}' test.csv|sort|uniq
Returns:
dog
cat
bird
Thank you for your help!
Just with awk:
awk -F, '{count[$1]++} END {for (key in count) if (count[key] == 1) print key}' test.csv
Close. Try:
awk -F"," '{print $1}' test.csv |sort | uniq -c | awk '{if ($1 == 1) print $2}'
the -c flag on uniq will give you counts. Next awk will look for any items with the count of 1 (first field) and print the value of the second field ($2)
Only caveat is that this will return bird before cat due to it being previously sroted. you could pipe once more to sort -r to reverse the sort direction. This would be identical to the expected answer you asked for, but it is not the original sort order.
Cutting to first field, then sorting and displaying only uniques:
cut -d ',' -f 1 test.csv | sort | uniq -u
That is, if you append -u to your command, it'd work. This is just using cut instead of awk.
If Perl is an option, this code is similar to #glenn jackman's:
perl -F, -lane '$c{$F[0]}++; END{for $k (sort keys %c){print $k if $c{$k} == 1}}' test.csv
These command-line options are used:
-n loop around each line of the input file
-l removes newlines before processing, and adds them back in afterwards
-a autosplit mode – split input lines into the #F array. Defaults to splitting on whitespace.
-e execute the perl code
-F autosplit modifier, in this case splits on ,
#F is the array of words in each line, indexed starting with $F[0]
I have a file that is delimited by comma ",", but some rows have only one column, and some rows have multiple columns separated by ",". For example:
NM_001066
NM_015378,NM_018156
NM_001006624,NM_001006625,NM_006474,NM_198389
As you can see above, the third line has 4 columns delimited by ",", but I only need to get the first column in every line.
I tried to use awk: cat fileName.txt | awk '{print $1}', but it does not work. I am looking for help with this. Thank you!
I guess you're looking for this:
awk -F, '{print $1}' file.txt
-F, tells awk to use comma as the field separator.
In this simple case, the same thing is simpler with cut:
cut -f1 -d, file.txt
you are close:
awk -F, '{print $1}' file
or
awk -F, '$0=$1' file
I am trying to print the rows from a csv file that have a third column value greater than -39. I have tried using awk but have not been able to get the command to work:
awk -F "," '{$3 > -39}' momenttensors.csv
You have your comparison inside an action block. You want it in the pattern section. Remove the { and }.
awk -F, '$3 > -39' momenttensors.csv
Try this:
awk -F, '$3 > -39' momenttensors.csv
You need the test part. {} this is an action part.
i have to use awk to print out 4 different columns in a csv file. The problem is the strings are in a $x,xxx.xx format. When I run the regular awk command.
awk -F, {print $1} testfile.csv
my output `ends up looking like
307.00
$132.34
30.23
What am I doing wrong.
"$141,818.88","$52,831,578.53","$52,788,069.53"
this is roughly the input. The file I have to parse is 90,000 rows and about 40 columns
This is how the input is laid out or at least the parts of it that I have to deal with. Sorry if I made you think this wasn't what I was talking about.
If the input is "$307.00","$132.34","$30.23"
I want the output to be in a
$307.00
$132.34
$30.23
Oddly enough I had to tackle this problem some time ago and I kept the code around to do it. You almost had it, but you need to get a bit tricky with your field separator(s).
awk -F'","|^"|"$' '{print $2}' testfile.csv
Input
# cat testfile.csv
"$141,818.88","$52,831,578.53","$52,788,069.53"
"$2,558.20","$482,619.11","$9,687,142.69"
"$786.48","$8,568,159.41","$159,180,818.00"
Output
# awk -F'","|^"|"$' '{print $2}' testfile.csv
$141,818.88
$2,558.20
$786.48
You'll note that the "first" field is actually $2 because of the field separator ^". Small price to pay for a short 1-liner if you ask me.
I think what you're saying is that you want to split the input into CSV fields while not getting tripped up by the commas inside the double quotes. If so...
First, use "," as the field separator, like this:
awk -F'","' '{print $1}'
But then you'll still end up with a stray double-quote at the beginning of $1 (and at the end of the last field). Handle that by stripping quotes out with gsub, like this:
awk -F'","' '{x=$1; gsub("\"","",x); print x}'
Result:
echo '"abc,def","ghi,xyz"' | awk -F'","' '{x=$1; gsub("\"","",x); print x}'
abc,def
In order to let awk handle quoted fields that contain the field separator, you can use a small script I wrote called csvquote. It temporarily replaces the offending commas with nonprinting characters, and then you restore them at the end of your pipeline. Like this:
csvquote testfile.csv | awk -F, {print $1} | csvquote -u
This would also work with any other UNIX text processing program like cut:
csvquote testfile.csv | cut -d, -f1 | csvquote -u
You can get the csvquote code here: https://github.com/dbro/csvquote
The data file:
$ cat data.txt
"$307.00","$132.34","$30.23"
The AWK script:
$ cat csv.awk
BEGIN { RS = "," }
{ gsub("\"", "", $1);
print $1 }
The execution:
$ awk -f csv.awk data.txt
$307.00
$132.34
$30.23