Iterating over different variables in bash script

Question

[Fatima]

I have a few lists of samples that I need to use, but I don't know how to address them in bash script.

declare -a sample1=("402.fasta" "440.fasta" "410.fasta" "405.fasta") 
declare  -a sample2=("403.fasta" "360.fasta" "230.fasta" "408.fasta") 
.
.
.
 declare -a sample9=("400.fasta" "340.fasta" "360.fasta" "436.fasta")

I don't know how to iterate over different values.

I need something like

for((i=1;i<10;i++));
do
for((j=0,j<4;j++));
var=sample$i
echo ${!var[$j]}
done
done

But it only returns 402.fasta, 403.fasta,... 400.fasta, the first file in each sample set!

I have a script that I need to pass files in each set separated by comma to this script, for example

somescript 402.fasta,440.fasta,410.fasta,405.fasta

for((i=1;i<10;i++));
do 
somescript ${set$i[0]}, ${set$i[1]},${set$i[2]},${set$i[3]}              
done

but ${set$i[3]} doesn't work

And also I need to run LINE_COUNT=$(find . -type f -print0 | wc -l allfilesinset1 | grep "total") echo $LINE_COUNT

If all files in set 1 were in directory1 instead of allfilesinset1 I could use set1/*.fasta but I don't want to change the data sets or cat them together because it takes space, and also I need them individually too.

[st.ph.n]

I think in the over-generalization in the question, and further lack of details makes this difficult to understand. Perhaps write out some psuedocode, to better illustrate the steps you want to complete. I think your end goal is unclear.

Answer 1

[st.ph.n]

If you always have 4 variables per run, you can use xargs.

List your filenames in a text file:

402.fasta 440.fasta 410.fasta 405.fasta 
403.fasta 360.fasta 230.fasta 408.fasta
...

400.fasta 340.fasta 360.fasta 436.fasta

$1, $2, $3, $4 would be passed to your script, as each variable.

So, running:

cat variables.txt | xargs -n 4 bash somescript.sh

is the same as

bash somescript.sh 402.fasta 440.fasta 410.fasta 405.fasta

but it will run as many time as lines your have in your variable.txt

To get the line count, you will have to cat the files, but you don't need to put them into a new file.

cat $1 $2 $3 $4 | wc -l

[Fatima]

Thanks, from your code I wrote the file names in a text file, each sample set in one line, as you said. And used bash script.sh $(awk 'NR==$j+1' filename) to run my script :)

Also used Alex's code to access each file individually.

[Friederike]

what's wrong with using Alex's response?

for SAMPLE in `seq 1 1 9`
do
    for REPLICATE in `seq 1 1 4`
    do
        wc -l value$SAMPLE$REPLICATE.fasta | grep "total"
    done
done

[Fatima]

Thanks, but as I commented in Alex's post, I don't need to print value$i$j, I need to print value[$i][$j]. My filenames do not start with value, I just tried to generalize my question. Sorry for the confusion.

sample1=("filename1" "filename2"...)
sample2=("filename5" "filename6"...)

[GenoMax]

Post full format examples of the file names e.g. my_sample_1.fq.gz.

Answer 2

[Alex Reynolds]

#!/bin/bash                                                                                                                                                                                             

declare -a sample1=("402.fasta" "440.fasta" "410.fasta" "405.fasta")
declare -a sample2=("403.fasta" "360.fasta" "230.fasta" "408.fasta")
declare -a samples=("sample1" "sample2")

for i in `seq 0 1 1`
do
    echo "${samples[$i]}"
    for j in `seq 0 1 3`
    do
        value=${samples[$i]}[$j]
        echo ${!value}
    done
done

Prints:

$ ./iterate_v2.sh
sample1
402.fasta
440.fasta
410.fasta
405.fasta
sample2
403.fasta
360.fasta
230.fasta
408.fasta

Answer 3

[Alex Reynolds]

Or if you don't want to create a third array:

#!/bin/bash

declare -a sample1=("402.fasta" "440.fasta" "410.fasta" "405.fasta")
declare -a sample2=("403.fasta" "360.fasta" "230.fasta" "408.fasta")

for i in `seq 1 1 2`
do
    sample=sample$i
    echo ${sample}
    for j in `seq 0 1 3`
    do
        value=${sample}[$j]
        echo ${!value}
    done
done

You just have to be careful about indexing, as here you're using 1-based indexing for the sample names, and 0-based indexing for referencing elements in the sample arrays. This requires different values to seq in the inner and outer loops.

In any case, both this answer and the others should demonstrate the principles you need to solve this in bash.

Answer 4

[Alex Reynolds]

The following script:

#!/bin/bash

for i in `seq 1 1 9`
do
    for j in `seq 1 1 4`
    do
        echo "value$i$j"
    done
done

prints:

$ ./iterate.sh
value11
value12
value13
value14
value21
...
value93
value94

If you need arrays of arrays, you're probably better off with writing a script in Perl or Python.

[Fatima]

I updated my question to resolve the confusions.

[Alex Reynolds]

Please see my second and third answers elsewhere in this thread.