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How to insert a column at the start of a txt file running from 1 to 2059 which corresponds to the number of rows I have in my file using awk. I know the command will be something like this:
awk '{$1=" "}1' File
Not sure what to put between the speech-marks 1-2059?
I also want to include a header in the header row so 1 should only go in the second row technically.
**ID** Heading1
RQ1293939 -7.0494
RG293I32SJ -903.6868
RQ19238983 -0899977
rq747585950 988349303
FID **ID** Heading1
1 RQ1293939 -7.0494
2 RG293I32SJ -903.6868
3 RQ19238983 -0899977
4 rq747585950 988349303
So I need to insert the FID with 1 - 2059 running down the first column
What you show does not work, it just replaces the first field ($1) with a space and prints the result. If you do not have empty lines try:
awk 'NR==1 {print "FID\t" $0; next} {print NR-1 "\t" $0}' File
Explanations:
NR is the awk variable that counts the records (the lines, in our case), starting from 1. So NR==1 is a condition that holds only when awk processes the first line. In this case the action block says to print FID, a tab (\t), the original line ($0), and then move to next line.
The second action block is executed only if the first one has not been executed (due to the final next statement). It prints NR-1, that is the line number minus one, a tab, and the original line.
If you have empty lines and you want to skip them we will need a counter variable to keep track of the current non-empty line number:
awk 'NR==1 {print "FID\t" $0; next} NF==0 {print; next} {print ++cnt "\t" $0}' File
Explanations:
NF is the awk variable that counts the fields in a record (the space-separated words, in our case). So NF==0 is a condition that holds only on empty lines (or lines that contain only spaces). In this case the action block says to print the empty line and move to the next.
The last action block is executed only if none of the two others have been executed (due to their final next statement). It increments the cnt variable, prints it, prints a tab, and prints the original line.
Uninitialized awk variables (like cnt in our example) take value 0 when they are used for the first time as a number. ++cnt increments variable cnt before its value is used by the print command. So the first time this block is executed cnt takes value 1 before being printed. Note that cnt++ would increment after the printing.
Assuming you don't really have a blank row between your header line and the rest of your data:
awk '{print (NR>1 ? NR-1 : "FID"), $0}' file
Use awk -v OFS='\t' '...' file if you want the output to be tab-separated or pipe it to column -t if you want it visually tabular.
I have two large files (~10GB) as follows:
file1.csv
name,id,dob,year,age,score
Mike,1,2014-01-01,2016,2,20
Ellen,2, 2012-01-01,2016,4,35
.
.
file2.csv
id,course_name,course_id
1,math,101
1,physics,102
1,chemistry,103
2,math,101
2,physics,102
2,chemistry,103
.
.
I want to subtract 1 from the "id" columns of these files:
file1_updated.csv
name,id,dob,year,age,score
Mike,0,2014-01-01,2016,2,20
Ellen,0, 2012-01-01,2016,4,35
file2_updated.csv
id,course_name,course_id
0,math,101
0,physics,102
0,chemistry,103
1,math,101
1,physics,102
1,chemistry,103
I have tried awk '{print ($1 - 1) "," $0}' file2.csv, but did not get the correct result:
-1,id,course_name,course_id
0,1,math,101
0,1,physics,102
0,1,chemistry,103
1,2,math,101
1,2,physics,102
1,2,chemistry,103
You've added an extra column in your attempt. Instead set your first field $1 to $1-1:
awk -F"," 'BEGIN{OFS=","} {$1=$1-1;print $0}' file2.csv
That semicolon separates the commands. We set the delimiter to comma (-F",") and the Output Field Seperator to comma BEGIN{OFS=","}. The first command to subtract 1 from the first field executes first, then the print command executes second, so the entire record, $0, will now contain the new $1 value when it's printed.
It might be helpful to only subtract 1 from records that are not your header. So you can add a condition to the first command:
awk -F"," 'BEGIN{OFS=","} NR>1{$1=$1-1} {print $0}' file2.csv
Now we only subtract when the record number (NR) is greater than 1. Then we just print the entire record.
I want to split and comparison in awk command.
Input file (tab-delimited)
1 aaa 1|3
2 bbb 3|3
3 ccc 0|2
Filtration
First column value > 1
First value of third column value splitted by "|" > 2
Process
Compare first column value if bigger than 1
Split third column value by "|"
Compare first value of the third column if bigger than 2
Print if the first value bigger than 2 only
Command line (example)
awk -F "\t" '{if($1>1 && ....?) print}' file
Output
2 bbb 3|3
Please let me know command line for above processing.
You can set the field separator to either tab or pipe and check the 1st and 3rd values:
awk -F'\t|\\|' '$1>1 && $3>2' file
or
awk -F"\t|\\\\|" '$1>1 && $3>2' file
You can read about all this character escaping in this comprehensive answer by Ed Morton in awk: fatal: Invalid regular expression when setting multiple field separators.
Otherwise, you can split the 3rd field and check the value of the first slice:
awk -F"\t" '{split($3,a,"|")} $1>1 && a[1]>=2' file
I would like to compare two files and do something like this: if the 5th column in the first file is equal to the 5th column in the second file, I would like to print the whole line from the first file. Is that possible? I searched for the issue but was unable to find a solution :(
The files are separated by tabulators and I tried something like this:
zcat file1.txt.gz file2.txt.gz | awk -F'\t' 'NR==FNR{a[$5];next}$5 in a {print $0}'
Did anybody tried to do a similar thing? :)
Thanks in advance for help!
Your script is fine, but you need to provide each file individually to awk and in reverse order.
$ cat file1.txt
a b c d 100
x y z w 200
p q r s 300
1 2 3 4 400
$ cat file2.txt
. . . . 200
. . . . 400
$ awk 'NR==FNR{a[$5];next} $5 in a {print $0}' file2.txt file1.txt
x y z w 200
1 2 3 4 400
EDIT:
As pointed out in the comments, the generic solution above can be improved and tailored to OP's situation of starting with compressed tab-separated files:
$ awk -F'\t' 'NR==FNR{a[$5];next} $5 in a' <(zcat file2.txt) <(zcat file1.txt)
x y z w 200
1 2 3 4 400
Explanation:
NR is the number of the current record being processed and FNR is the number
of the current record within its file . Thus NR == FNR is only
true when awk is processing the first file given to it (which in our case is file2.txt).
a[$5] adds the value of the 5th column as an index to the array a. Arrays in awk are associative arrays, but often you don't care about associating a value and just want to make a nice collection of things. This is a
pithy way to make a collection of all the values we've seen in 5th column of the
first file. The next statement, which follows, says to immediately get the next
available record without looking at any anymore statements in the awk program.
Summarizing the above, this line says "If you're reading the first file (file2.txt),
save the value of column 5 in the array called a and move on to the record without
continuing with the rest of the awk program."
NR == FNR { a[$5]; next }
Hopefully it's clear from the above that the only way we can past that first line of
the awk program is if we are reading the second file (file1.txt in our case).
$5 in a evaluates to true if the value of the 5th column occurs as an index in
the a array. In other words, it is true for every record in file1.txt whose 5th
column we saw as a value in the 5th column of file2.txt.
In awk, when the pattern portion evaluates to true, the accompanying action is
invoked. When there's no action given, as below, the default action is triggered
instead, which is to simply print the current record. Thus, by just saying
$5 in a, we are telling awk to print all the records in file1.txt whose 5th
column also occurs in file2.txt, which of course was the given requirement.
$5 in a
I have a CSV file that look like this:
A,B,C
1,2,3
4,4,4
1,2,6
3,6,9
Is there an easy way to grep all the rows in which the B column is 2, and keep the header? For example, I want the output be like
A,B,C
1,2,3
1,2,6
I am working under linux
Using awk:
awk -F, 'NR==1 || $2==2' file
NR==1 -> if first line,
$2==2 -> if second column is equal to 2. Lines are printed if either of the above is true.
To choose the column using the header column name:
awk -F, -v col="B" 'NR==1{for(i=1;i<=NF;i++)if($i==col)break;print;next}$i==2' file
Replace B with the appropriate name of the column which you want to check against.
You can use addresses in sed:
sed -n '1p;/^[^,]*,2/p'
It means:
1p Print the first line.
/ Start a match.
^ Match the beginnning of a line.
[^,] Match anything but a comma
* zero or more times.
, Match a comma.
2 Match a 2.
/p End of match, if it matches, print.
If the header can contain the value you are looking for, you should be more careful:
sed -n '1p;1!{/^[^,]*,2/p}'
1!{ ... } just means "Do the following for lines other then the first one".
For column number n>2, you can add a quantifier:
sed -n '1p;1!{/^\([^,]*,\)\{M\}2/p}'
where M=n-1. The quantifier just means repetition, so the non-comma-0-or-more-times-comma thing is repeated M times.
For true CSV files where a value can contain a comma, switch to Perl and Text::CSV.
$ awk -F, 'NR==1 { for (i=1;i<=NF;i++) h[$i] = i; print; next } $h["B"] == 2' file
A,B,C
1,2,3
1,2,6
By the way, sed is an excellent tool for simple substitutions on a single line, for anything else, just use awk - the code will be clearer and MUCH easier to enhance in future if necessary.