Question 110568 in Json Question posted in
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Json – How to extract numerical value from array of string in bash

If array = ["stack","overflow","5","6","question","9"]

I want to make another array to store all numerical values like:
new_arr = [5,6,9] in bash.

Tags:

4

Answers


  1. 0

    With a for loop you will be able to go through your array and then, get inspiration with this post to determine if your iterator’s value is a number or a string.

    In case of a numerical value, just append it to another array.

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  2. 0

    With :

    The proper tool for your proper input:

    array = ["stack","overflow","5","6","question","9"]

    #!/bin/bash

arr=( $(
    node<<EOF
    new_arr = ["stack","overflow","5","6","question","9"]
    .filter(e => e.match(/^d+$/));
    new_arr.forEach(e => console.log(e))
EOF
)) 
printf '%sn' "${arr[@]}" # plain bash array

    Online test

    new_arr = ["stack","overflow","5","6","question","9"]
.filter(e => e.match(/^d+$/));
new_arr.forEach(e => console.log(e))
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  3. 0

    This is how you can do in bash:

    # declare original array
arr=("stack" "overflow" "5" "6" "question" "9")

# remove all elements that have at least one non-digit character
narr=(${arr[@]//*[!0-9]*})

# check content of narr
declare -p narr

    Output:

    declare -a narr='([0]="5" [1]="6" [2]="9")'
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  4. 0

    In pure bash with comments inline:

    #!/bin/bash

# the initial array
array=( "stack" "overflow" "5" "6" "question" "9" )

# declare the final array
declare -a new_arr

# loop over the original values
for val in "${array[@]}"
do
    # use regex to filter out those with only digits
    if [[ $val =~ ^[0-9]+$ ]];
    then
        # and append them to new_arr
        new_arr+=($val)
    fi
done

# print the result
for val in "${new_arr[@]}"
do
    echo "$val"
done

    If array is a scalar

    array='["stack","overflow","5","6","question","9"]'

    you should use a parser. is useful for generic stream editing and is a parser specifically made to deal with JSON data.

    Here jq used to select only those values that contain at least 1 character and where all characters must be numbers using the ^[0-9]+$:

    readarray -t new_arr < <(echo "$array" | jq -r '.[] | select(test("^[0-9]+$"))')
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