Iteration to count the number of raw reads

Question

[wanaga3166]

Hi everyone,

I made a short script to count the number of raw reads (fastq.gz) in my folder. The results will save in a text file (.txt).

echo "We count the number of reads for each file (fastq.gz)."
echo "file\traw_reads\ttrimmed_reads" > count_read_evolution_trim_test.txt
for f1 in *paired.fq.gz
  do
     echo $f1
     RAW_READS=`gunzip -c $f1 | echo $((`wc -l`/4))`
     echo -e "$f1\t$RAW_READS" >> count_read_evolution_trim_test.txt
  done

But I obtained this error message:

./test_count_raw_reads.sh: command substitution: line 9: syntax error near unexpected token `)'
./test_count_raw_reads.sh: command substitution: line 9: `/4))'
./test_count_raw_reads.sh: command substitution: line 9: unexpected EOF while looking for matching `)'
./test_count_raw_reads.sh: command substitution: line 10: syntax error: unexpected end of file
./test_count_raw_reads.sh: line 9: -l: command not found code here

How I can fix this problem?

Thank you.

[wanaga3166]

When I did this command line:

gunzip -c $f1 | echo $((`wc -l`/4))

It works, I obtained the number of raw reads. I just want to put the number of raw reads in a table, like in this example.

file | raw_read_number

my_file_1 | 130000

my_file_2 | 160000

my_file_3 | 200000

I don't understand where I did a mistake.

[Pierre Lindenbaum]

gunzip -c $f1 | echo 

you're piping a stream in echo : wrong

[Martombo]

your use of ` is messing up this line:

`gunzip -c $f1 | echo $((`wc -l`/4))`

[wanaga3166]

If you watch my initial code (in the top) of this post, I put the back quote as you wrote. And I can't save the number of raw reads in my text table (count_read_evolution_trim_test.txt).

The problem in my code, that a I have two backquote in this line:

RAW_READS=`gunzip -c $f1 | echo $((`wc -l`/4))`

And it doesn't count the raw reads number.

Answer 1

[Martombo]

Yep, exactly. The second ` stops the expression at:

`gunzip -c $f1 | echo $((`

If you want to keep this line you can maybe use awk to divide by 4:

RAW_READS=`gunzip -c $f1 | wc -l | awk '{print($1/4)}'`

edit: this is probably more efficient:

RAW_READS=`gunzip -c $f1 | awk 'END{print(NR/4)}'`

[wanaga3166]

Thank you Martombo. Your solution works. I will be more careful with the backquotes.

Answer 2

[Pierre Lindenbaum]

you want:

find . -name "*q.gz" | while read F; do echo -n "$F " && echo $(( $(gunzip -c $F | wc -l) / 4 )) ; done

[wanaga3166]

When I did this command line:

gunzip -c $f1 | echo $((wc -l/4)) It works, I obtained the number of raw reads. I just want to put the number of raw reads in a table, like in this example.

file | raw_read_number my_file_1 | 130000 my_file_2 | 160000 my_file_3 | 200000 I don't understand where I did a mistake.

Answer 3

[2nelly]

Hi wanaga3166

what about this:

for f in *fastq.gz; do echo -n "$f | "  && echo $(($(zcat $f | echo $((`wc -l`/4))))); done > output && sed  -i '1i file | raw_read_number' output