Have data like this:

id     timestamp          collection
1111    1721681210135     music
2222    1721681210140     weather
1111    1721681210100     art
1111    1721681210000     music
.........

need to aggregate to a dictionary like column after group by
expected output is like:

id      collection_counts
1111    "music":2,"art":1
2222    "weather":1
............

Which function could be proper for this purpose?