Replacing a specific field using awk, sed or any POSIX tool - bash

I have a huge file1, which has values as follows:
a 1
b 2
c 3
d 4
e 5
I have another huge file2, which is colon delimited with seven fields as follows:
a:2543:2524:2542:252:536365:54654
c:5454:5454:654:54:87:54
d:87:65:1:98:32:87
I want to search the lines for the variables of file1 and replace its value in the 7th column in file2 so the output should be as follows:
a:2543:2524:2542:252:536365:1
c:5454:5454:654:54:87:3
d:87:65:1:98:32:4

Maybe this awk will work, assuming the files are as posted
awk -F: 'NR==FNR{a[$1]=$0;next;}a[$1]{$0=a[$1]}1' file1 file2
a:2543:2524:2542:252:536365:1
c:5454:5454:654:54:87:3
d:87:65:1:98:32:4

So I came up with a solution; ended up with a couple of lines of code. Maybe there is a better way to do it.But this works !
while read line ; do
var1=`echo $line| awk '{print $1}'`
var2=`echo $line| awk '{print $2}'`
awk -v var1="$var1" -v var2="$var2" -F ':' 'BEGIN { OFS = ":"} $1==var1 {sub(".*",var2,$7)}{print}' file2 > file2.tmp
mv file2.tmp file2
done < file1
cat file2

This should work - it assumes both files are sorted on the first column - I'd be very interested in any performance comparisons with your solution for very large files - both speed and memory - --complement is linux-specific but easily replaced if not available
file0=$1 #file with single value
file1=$2 #file with 6th value to be replaced
# normalize on colon delimiter
tr ' ' : <$file0|
# join on first field
join -t: $file1 -|
# delete column 7
cut --complement -d: -f7

Related

Write specific columns of files into another files, Who can give me a more concise solution?

I have a troublesome problem about writing specific columns of the file into another file, more details are I have the file1 like below, I need to write the first columns exclude the first row to file2 with one line and separated with '|' sign. And now I have a solution by sed and awk, this missing last step inserts into the top of file2, even though I still believe there should be some more concise solution on account of powerful of awk、sed, etc. So, Who can offer me another more concise script?
sed '1d;s/ .//' ./file1 | awk '{printf "%s|", $1; }' | awk '{if (NR != 0) {print substr($1, 1, length($1) - 1)}}'
file1:
col_name data_type comment
aaa string null
bbb int null
ccc int null
file2:
xxx ccc(whatever is this)
The result of file2 should be this :
aaa|bbb|ccc
xxx ccc(whatever is this)
Assuming there's no whitespace in the column 1 data, in increasing length:
sed -i "1i$(awk 'NR > 1 {print $1}' file1 | paste -sd '|')" file2
or
ed file2 <<END
1i
$(awk 'NR > 1 {print $1}' file1 | paste -sd '|')
.
wq
END
or
{ awk 'NR > 1 {print $1}' file1 | paste -sd '|'; cat file2; } | sponge file2
or
mapfile -t lines < <(tail -n +2 file1)
col1=( "${lines[#]%%[[:blank:]]*}" )
new=$(IFS='|'; echo "${col1[*]}"; cat file2)
echo "$new" > file2
This might work for you (GNU sed):
sed -z 's/[^\n]*\n//;s/\(\S*\).*/\1/mg;y/\n/|/;s/|$/\n/;r file2' file1
Process file1 "wholemeal" by using the -z command line option.
Remove the first line.
Remove all columns other than the first.
Replace newlines by |'s
Replace the last | by a newline.
Append file2.
Alternative using just command line utils:
tail +2 file1 | cut -d' ' -f1 | paste -s -d'|' | cat - file2
Tail file1 from line 2 onwards.
Using the results from the tail command, isolate the first column using a space as the column delimiter.
Using the results from the cut command, serialize each line into one, delimited by |',s.
Using the results from the paste, append file2 using the cat command.
I'm learning awk at the moment.
awk 'BEGIN{a=""} {if(NR>1) a = a $1 "|"} END{a=substr(a, 1, length(a)-1); print a}' file1
Edit: Here's another version that uses an array:
awk 'NR > 1 {a[++n]=$1} END{for(i=1; i<=n; ++i){if(i>1) printf("|"); printf("%s", a[i])} printf("\n")}' file1
Here is a simple Awk script to merge the files as per your spec.
awk '# From the first file, merge all lines except the first
NR == FNR { if (FNR > 1) { printf "%s%s", sep, $1; sep = "|"; } next }
# We are in the second file; add a newline after data from first file
FNR == 1 { printf "\n" }
# Simply print all lines from file2
1' file1 file2
The NR==FNR condition is true when we are reading the first input file: The overall line number NR is equal to the line number within the current file FNR. The final 1 is a common idiom for printing all input lines which make it this far into the script (the next in the first block prevent lines from the first file to reaching this far).
For conciseness, you can remove the comments.
awk 'NR == FNR { if (FNR > 1) { printf "%s%s", sep, $1; sep = "|"; } next }
FNR == 1 { printf "\n" } 1' file1 file2
Generally speaking, Awk can do everything sed can do, so piping sed into Awk (or vice versa) is nearly always a useless use of sed.

How to merge in one file, two files in bash line by line [duplicate]

What's the easiest/quickest way to interleave the lines of two (or more) text files? Example:
File 1:
line1.1
line1.2
line1.3
File 2:
line2.1
line2.2
line2.3
Interleaved:
line1.1
line2.1
line1.2
line2.2
line1.3
line2.3
Sure it's easy to write a little Perl script that opens them both and does the task. But I was wondering if it's possible to get away with fewer code, maybe a one-liner using Unix tools?
paste -d '\n' file1 file2
Here's a solution using awk:
awk '{print; if(getline < "file2") print}' file1
produces this output:
line 1 from file1
line 1 from file2
line 2 from file1
line 2 from file2
...etc
Using awk can be useful if you want to add some extra formatting to the output, for example if you want to label each line based on which file it comes from:
awk '{print "1: "$0; if(getline < "file2") print "2: "$0}' file1
produces this output:
1: line 1 from file1
2: line 1 from file2
1: line 2 from file1
2: line 2 from file2
...etc
Note: this code assumes that file1 is of greater than or equal length to file2.
If file1 contains more lines than file2 and you want to output blank lines for file2 after it finishes, add an else clause to the getline test:
awk '{print; if(getline < "file2") print; else print ""}' file1
or
awk '{print "1: "$0; if(getline < "file2") print "2: "$0; else print"2: "}' file1
#Sujoy's answer points in a useful direction. You can add line numbers, sort, and strip the line numbers:
(cat -n file1 ; cat -n file2 ) | sort -n | cut -f2-
Note (of interest to me) this needs a little more work to get the ordering right if instead of static files you use the output of commands that may run slower or faster than one another. In that case you need to add/sort/remove another tag in addition to the line numbers:
(cat -n <(command1...) | sed 's/^/1\t/' ; cat -n <(command2...) | sed 's/^/2\t/' ; cat -n <(command3) | sed 's/^/3\t/' ) \
| sort -n | cut -f2- | sort -n | cut -f2-
With GNU sed:
sed 'R file2' file1
Output:
line1.1
line2.1
line1.2
line2.2
line1.3
line2.3
Here's a GUI way to do it: Paste them into two columns in a spreadsheet, copy all cells out, then use regular expressions to replace tabs with newlines.
cat file1 file2 |sort -t. -k 2.1
Here its specified that the separater is "." and that we are sorting on the first character of the second field.

Extracting unique values between 2 files with awk

I need to get uniq lines when comparing 2 files. These files containing field separator ":" which should be treated as the end of line while comparing strings.
The file1 contains these lines
apple:tasty
apple:red
orange:nice
kiwi:awesome
kiwi:expensive
banana:big
grape:green
orange:oval
banana:long
The file2 contains these lines
orange:nice
banana:long
The output file should be (2 occurrences of orange and 2 occurrences of banana deleted)
apple:tasty
apple:red
kiwi:awesome
kiwi:expensive
grape:green
So the only strings before : should be compared
Is it possible to complete this task in 1 command ?
I tried to complete the task in such way but field separator does not work in that situation.
awk -F: 'FNR==NR {a[$0]++; next} !a[$0]' file1 file2 > outputfile
You basically had it, but $0 refers to the whole line when you want to deal with only the first field, which is $1.
Also you need to take care with the order of the input files. To use the values from file2 for deciding which lines to include from file1, process file2 first:
$ awk -F: 'FNR==NR {a[$1]++; next} !a[$1]' file2 file1
apple:tasty
apple:red
kiwi:awesome
kiwi:expensive
grape:green
One comment: awk is very ineffective with arrays. In real life with big files, better use something like:
comm -3 <(cut -d : -f 1 f1 | sort -u) <(cut -d : -f 1 f2 | sort -u) | grep -h -f /dev/stdin f1 f2

Explode to Array

I put together this shell script to do two things:
Change the delimiters in a data file ('::' to ',' in this case)
Select the columns and I want and append them to a new file
It works but I want a better way to do this. I specifically want to find an alternative method for exploding each line into an array. Using command line arguments doesn't seem like the way to go. ANY COMMENTS ARE WELCOME.
# Takes :: separated file as 1st parameters
SOURCE=$1
# create csv target file
TARGET=${SOURCE/dat/csv}
touch $TARGET
echo #userId,itemId > $TARGET
IFS=","
while read LINE
do
# Replaces all matches of :: with a ,
CSV_LINE=${LINE//::/,}
set -- $CSV_LINE
echo "$1,$2" >> $TARGET
done < $SOURCE
Instead of set, you can use an array:
arr=($CSV_LINE)
echo "${arr[0]},${arr[1]}"
The following would print columns 1 and 2 from infile.dat. Replace with
a comma-separated list of the numbered columns you do want.
awk 'BEGIN { IFS='::'; OFS=","; } { print $1, $2 }' infile.dat > infile.csv
Perl probably has a 1 liner to do it.
Awk can probably do it easily too.
My first reaction is a combination of awk and sed:
Sed to convert the delimiters
Awk to process specific columns
cat inputfile | sed -e 's/::/,/g' | awk -F, '{print $1, $2}'
# Or to avoid a UUOC award (and prolong the life of your keyboard by 3 characters
sed -e 's/::/,/g' inputfile | awk -F, '{print $1, $2}'
awk is indeed the right tool for the job here, it's a simple one-liner.
$ cat test.in
a::b::c
d::e::f
g::h::i
$ awk -F:: -v OFS=, '{$1=$1;print;print $2,$3 >> "altfile"}' test.in
a,b,c
d,e,f
g,h,i
$ cat altfile
b,c
e,f
h,i
$

Comparing values in two files

I am comparing two files, each having one column and n number of rows.
file 1
vincy
alex
robin
file 2
Allen
Alex
Aaron
ralph
robin
if the data of file 1 is present in file 2 it should return 1 or else 0, in a tab seprated file.
Something like this
vincy 0
alex 1
robin 1
What I am doing is
#!/bin/bash
for i in `cat file1 `
do
cat file2 | awk '{ if ($1=="'$i'") print 1 ; else print 0 }'>>binary
done
the above code is not giving me the output which I am looking for.
Kindly have a look and suggest correction.
Thank you
The simple awk solution:
awk 'NR==FNR{ seen[$0]=1 } NR!=FNR{ print $0 " " seen[$0] + 0}' file2 file1
A simple explanation: for the lines in file2, NR==FNR, so the first action is executed and we simply record that a line has been seen. In file1, the 2nd action is taken and the line is printed, followed by a space, followed by a "0" or a "1", depending on if the line was seen in file2.
AWK loves to do this kind of thing.
awk 'FNR == NR {a[tolower($1)]; next} {f = 0; if (tolower($1) in a) {f = 1}; print $1, f}' file2 file1
Swap the positions of file2 and file1 in the argument list to make file1 the dictionary instead of file2.
When FNR (the record number in the current file) and NR (the record number of all records so far) are equal, then the first file is the one being processed. Simply referencing an array element brings it into existence. This sets up the dictionary. The next instruction reads the next record.
Once FNR and NR aren't equal, subsequent file(s) are being processed and their data is looked up in the dictionary array.
The following code should do it.
Take a close look to the BEGIN and END sections.
#!/bin/bash
rm -f binary
for i in $(cat file1); do
awk 'BEGIN {isthere=0;} { if ($1=="'$i'") isthere=1;} END { print "'$i'",isthere}' < file2 >> binary
done
There are several decent approaches. You can simply use line-by-line set math:
{
grep -xF -f file1 file2 | sed $'s/$/\t1/'
grep -vxF -f file1 file2 | sed $'s/$/\t0/'
} > somefile.txt
Another approach would be to simply combine the files and use uniq -c, then just swap the numeric column with something like awk:
sort file1 file2 | uniq -c | awk '{ print $2"\t"$1 }'
The comm command exists to do this kind of comparison for you.
The following approach does only one pass and scales well to very large input lists:
#!/bin/bash
while read; do
if [[ $REPLY = $'\t'* ]] ; then
printf "%s\t0\n" "${REPLY#?}"
else
printf "%s\t1\n" "${REPLY}"
fi
done < <(comm -2 <(tr '[A-Z]' '[a-z]' <file1 | sort) <(tr '[A-Z]' '[a-z]' <file2 | sort))
See also BashFAQ #36, which is directly on-point.
Another solution, if you have python installed.
If you're familiar with Python and are interested in the solution, you only need a bit of formatting.
#/bin/python
f1 = open('file1').readlines()
f2 = open('file2').readlines()
f1_in_f2 = [int(x in f2) for x in f1]
for n,c in zip(f1, f1_in_f2):
print n,c

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