Multiply every element of an array by the same scalar in zsh-CodePudding

I would like to multiply every element in an array in zsh by the same scalar. I would be able to do this very easily in Python, but have looked in many places and cannot figure out how to do it in a zsh script.

I would like to write code like

#!/bin/zsh
mean=(1 2 2 1 -1 -2 -2 -1)
echo $((2 * $mean))

But when I try to do this I get the error message

bad math expression: operator expected at `2 2 1 -1 -...'

Any and all help would be appreciated. I can't seem to find anything online that is even remotely close to what I'm trying to figure out how to do.

CodePudding user response：

You have to iterate over the elements of the array and multiply each one:

#!/usr/bin/env zsh
typeset -a mean=(1 2 2 1 -1 -2 -2 -1)
for n in "${mean[@]}"; do
    print $((2 * n))
done

CodePudding user response：

There are some hacky ways to implement a map():

$ set -o extendedglob
$ a=(1 2 2 1 -1 -2 -2 -1)
$ print ${a//(#m)*/$((MATCH * 2))}
2 4 4 2 -2 -4 -4 -2

But a loop is probably the easiest:

$ b=(); for i ($a) b =$((i*2)); print $b
2 4 4 2 -2 -4 -4 -2