Count occurrences of item in JSON element grouped by another element - python-3.x

Question

I am trying to count the number of occurences of an item (Activity) in a json file grouped by another item (Source). Example json below.
{
"No": "9",
"Time": "08:12",
"Source": "location1",
"Dest": "location3",
"Activity": "fast"
}
My code below so far counts the occurences of each Activity
from collections import Counter
import json
with open('dataset_3.json', 'r') as json_file:
json_data = json.load(json_file) # loads json data
c = Counter(item['Activity'] for item in json_data)
print(c)
The code correctly counts and outputs below.
Counter({'fast': 8, 'medium': 1, 'slow': 1})
I would like now to count each occurence of activity again, but grouped by location so the output should be something like:
location 1 Fast: 8, Medium: 1, Slow: 2
loctaion 2 Fast: 6, Medium: 3, Slow: 4
I have tried the code below but the output is not correct (see below)
with open('dataset_3.json', 'r') as json_file:
json_data = json.load(json_file) # loads json data
for item in json_data:
if item['Source'] == 'location1':
c = Counter(item['Activity'])
print(c)
Output
Counter({'f': 3, 'a': 1, 's': 1, 't'})
Counter({'s': 1, 'l': 1, 'o': 1, 'w'})

Answer 1

You can put an if inside the generator statement for the Counter to add a condition to the for loop. I pasted your code with the fix below:
from collections import Counter
import json
with open('dataset_3.json', 'r') as json_file:
json_data = json.load(json_file) # loads json data
c = Counter(item['Activity'] for item in json_data if item['Source'] == 'location1')
print(c)