How do I check if any key-value pair appears more than once in a list of dictionaries?-CodePudding

For ex:

people_list = [{"name":"joe", "age":20}, {"name":"tom", "age":35}, {"name":"joe", "age":46}]

How do I check if any key-value pair appears more than once in this list of dictionaries?

I am aware of the counter function.

from collections import Counter

for i in range(len(people_list):
    Counter(people_list[i]["name"])
for key,value in Counter:
    if Counter(key:value) > 1:
        ...

Just not sure how to make it look and count for a specific key value pair in this list of dictionaries and check if it appears more than once.

CodePudding user response：

You want to collect all the keys from all the contained dictionaries into a single iterable that you can pass to your Counter instance. For this you could use itertools.chain. Then you can use a list comprehension:

from collections import Counter
from itertools import chain

l = [
    {'Booboo': 1},
    {"name":"joe", "age":20},
    {"name":"tom", "age":35},
    {"name":"joe", "age":46}
]

c = Counter(chain.from_iterable(l))
print([k for k in c if c[k] > 1])

Prints:

['name', 'age']

CodePudding user response：

If you want to get as output "joe", because it appears more than once for the key "name", then:

from collections import Counter

people_list = [{"name":"joe", "age":20}, {"name":"tom", "age":35}, {"name":"joe", "age":46}]
counter = Counter([person["name"] for person in people_list])
print([name for name, count in counter.items() if count > 1]) # ['joe']

CodePudding user response：

You can use collections.Counter and update like the below:

from collections import Counter

people_list = [{"name":"joe", "age":20}, {"name":"tom", "age":35}, {"name":"joe", "age":46}]
cnt = Counter()
for dct in people_list:
    cnt.update(dct.items())
print(cnt)

# Get the items > 1
for k,v in cnt.items():
    if v>1:
        print(k)

Output:

Counter({('name', 'joe'): 2, ('age', 20): 1, ('name', 'tom'): 1, ('age', 35): 1, ('age', 46): 1})

('name', 'joe')

CodePudding user response：

You can use a Counter to count the number of occurrences of each value and check if any key-value pair appears more than once.

from collections import Counter

people_list = [{"name":"joe", "age":20}, {"name":"tom", "age":35}, {"name":"joe", "age":46}]

# Count the number of occurrences of each value
counts = Counter(d["name"] for d in people_list)

# Check if any key-value pair appears more than once
for key, value in counts.items():
    if value > 1:
        print(f"{key} appears more than once")

Gives:

joe appears more than once