Bash - cut a text file into columns, slice strings and store value into arrays

Question

I would like some advice on some code.

I want to write a small script that will take an input file of this format

$cat filename.txt

111222233334444555666661112222AAAA
2222333445556612323244455445454545
2334556345643534505435345353453453

(and so on)

It will be called as : script inputfile X (where X is the number of slices you want to do)

I want the script to read the file and column-ize the slices, depending on user input, ie if he gave input 1,2 for the first slice, 3,4 for the second, the output would look like this:

#Here the first slice starts on the second digit, and length = 2 digits
#Here the second slice starts on the 3th digit and legth=4 digits



111 1222
222 2333
233 3455

This is what i have so far, but i only get the outputs of the first slicing arranged in a line, any advice please?

$./columncut filename.txt 2

#Initialize arrays
for ((i=1 ; i <= $2; i++)); do
        echo "Enter starting digit of $i string"; read a[i]
        echo "Enter length in digits of $i string"; read b[i]
done 

#Skim through file, slice strings

while read line
do
            for i in "${!a[@]}"; do
            str[i]=${line:${a[i]}:${b[i]}}
            done

            for i in "${!str[@]}"; do
            echo -n "$i "
            done


done <$1

I am unaware if there's an easier to do a job like this, perhaps with awk? Any help would be much appreciated.

I want to code it in bash, not for any weird preference, just what i was asked to do. — onlyf
– onlyf, Commented Nov 8, 2015 at 0:55
You should put bash as tag. without this your Q looks like if it's language-agnostic and nobody wants to answer. — Abstract type
– Abstract type, Commented Nov 8, 2015 at 3:03
Can't understand correspondence between input and output. Description is utterly unclear. — 4ae1e1
– 4ae1e1, Commented Nov 8, 2015 at 5:40
Please add a command demonstrating the desired parameters and the way you want to pass them to your script. — Yaron
– Yaron, Commented Nov 8, 2015 at 9:33
The script will be called as in : ./script filename number The number represents the amount of slices we would like to do on each line of filename. In the example input/output, the script is called like : ./script filename 2 — onlyf
– onlyf, Commented Nov 8, 2015 at 10:25

balabhi · Accepted Answer · 2015-11-08 15:20:42Z

2

#usage: bash slice.sh d.txt "1-2" "4-8" "10-20"  
#column postions 1-2, 4-8 and 10-20 printed.  
#Note that it is not length but col position.   

inf=$1 # source file  
shift  # arg1 is used up for file discard it.  
while read -r line  
do
    for fmt    #iterate over the arguments  
    do
        slice=`echo $line | cut -c $fmt`  # generate one slice  
        echo -n "$slice  "       # oupt with two blanks, but no newline  
    done
    echo ""  # Now give the newline                     
done < "$inf"

Sample run: bash slice.sh d.txt "1-2" "4-8" "10-15" 11 22223 334444
22 23334 555661
23 45563 564353

Probably it is not very difficult to store all these generated slices in array.

edited Nov 8, 2015 at 15:20

answered Nov 8, 2015 at 15:05

balabhi

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