Bash array to Python list format within bash script

Question

I would like to convert a bash array like echo ${b[*]} that outputs something like 1 10 100 1000 to a list format in Python: [1, 10, 100, 1000] that can be ready to use by a Python program. I need to do the conversion in a bash script.

I was doing it with for and if checking the positions, but wondering if there's something cleaner. Thx.

You can't create a python list in a bash script without using python, so I'm a little unclear as to what you are asking ... You could pass the string 1 10 100 1000 to a python script, parse it as a string, and split() it into a list, if that helps. — michjnich
– michjnich, Commented Aug 7, 2019 at 10:51
Why don't you just pass the array as a list of arguments to python? ./your-script.py "${b[@]}" and then read sys.argv in python? — Tom Fenech
– Tom Fenech, Commented Aug 7, 2019 at 11:00

Léa Gris · Accepted Answer · 2019-08-07 11:50:07Z

2

The correct way to do it is:

#!/usr/bin/env bash
my_list=(1 10 100 1000 "alpha" "beta")
s=''
printf '['
for e in "${my_list[@]}"; do
  if [[ "$e" = $((e)) ]]; then
    q=''
  else
    q='"'
  fi
  printf '%s%s%s%s' "$s" "$q" "$e" "$q"
  s=', '
 done
printf ']\n'

Turns Bash array:

(1 10 100 1000 "alpha" "beta")

Into Python array:

[1, 10, 100, 1000, "alpha", "beta"]

answered Aug 7, 2019 at 11:50

Léa Gris

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UtLox · Accepted Answer · 2019-08-07 11:31:48Z

2

You can try this:

echo "[${b[*]}]" | sed "s/ /, /g"

answered Aug 7, 2019 at 11:31

UtLox

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1 Comment

Léa Gris Over a year ago

This will not work if Bash array elements contains space or strings

Léa Gris · Accepted Answer · 2019-08-07 11:40:23Z

1

It would have too many ways too answer this question :

If you have a list of items :

my_list=(1, 10, 100, 1000); for i in $my_list; do echo $i; done

If you would make loop in range numbers:
```
for i in $(seq 1 20); do echo $i; done
```

If you would return exactly power of ten:

for i in $(seq 0 3); do echo $((10**i)); done

At the end I think your script would be third one, I hope it would be good to you.

edited Aug 7, 2019 at 11:40

Léa Gris

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answered Aug 7, 2019 at 11:28

Shervin Hariri

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