How to sort an associative array and retain the keys?

Question

I have an array with filenames as keys and a numerical value as values.

MYARRAY[00001.jpg] = 31
MYARRAY[00002.jpg] = 200
MYARRAY[00003.jpg] = 98

I need to sort them so they are ordered by value. Which I am doing with

IFS=$'\n' SORTED=($(sort <<<"${MYARRAY[*]}"))

However I lose the keys and just have numerical ones now.

Desired output would be

00001.jpg:31
00003.jpg:98
00002.jpg:200

How can I retain the keys in such a sort?

Solution

Assuming your keys don't contain colons or newlines and your values don't contain newlines:

for key in "${!MYARRAY[@]}"; do
  printf '%s:%s\n' "$key" "${MYARRAY[$key]}"
done | sort -t : -k 2n

If you need to arrange the key in the order given by the values, read back the output:

IFS=$'\n'; set -f
sorted_keys=($(
    for key in "${!MYARRAY[@]}"; do
      printf '%s:%s\n' "$key" "${MYARRAY[$key]}"
    done | sort -t : -k 2n | sed 's/:.*//'))
unset IFS; set +f

Comments

[dibs]

I can't seem to get useful output with this so far. Could you humour me a bit. What does the sed stuff do?

[Gilles 'SO- stop being evil']

@dibs The for loop prints out lines like 00001.jpg:31. The sed command removes the part after the colon. I fixed an error that caused sorted_keys to be a single string containing all the names, instead of an array as intended.

[pdolinaj]

How would I modify this function to display for example only the TOP 2 file names, without the count?

[von spotz]

@Gilles'SO-stopbeingevil' Hello, could you kindly explain what the -k 2n option means? Best wishes, von Spotz

[Gilles 'SO- stop being evil']

@vonspotz -k sets the sort key, i.e. what part of each line to use to sort. 2 means to start at the second field. n means to use numerical order rather than lexicographic order (so 9 sorts before 10).

[von spotz]

@Gilles'SO-stopbeingevil' Thank you very much!