Count the duplicates in a list of tuples
Solution 1
use collections library. In the following code val_1, val_2 give you duplicates of each first elements and second elements of the tuples respectively.
import collections
val_1=collections.Counter([x for (x,y) in a])
val_2=collections.Counter([y for (x,y) in a])
>>> print val_1
<<< Counter({1: 3, 2: 1, 6: 1})
This is the number of occurrences of the first element of each tuple
>>> print val_2
<<< Counter({2: 2, 9: 1, 4: 1, 7: 1})
This is the number of occurrences of the second element of each tuple
Solution 2
You can use a Counter
from collections import Counter
a = [(1,2),(1,4),(1,2),(6,7),(2,9)]
counter=Counter(a)
print counter
This will output:
Counter({(1, 2): 2, (6, 7): 1, (2, 9): 1, (1, 4): 1})
It is a dictionary like object with the item (tuples in this case) as the key and a value containing the number of times that key was seen. Your (1,2)
tuple is seen twice, while all others are only seen once.
>>> counter[(1,2)]
2
If you are interested in each individual portion of the tuple, you can utilize the same logic for each element in the tuple.
first_element = Counter([x for (x,y) in a])
second_element = Counter([y for (x,y) in a])
first_element
and second_element
now contain a Counter
of the number of times values are seen per element in the tuple
>>> first_element
Counter({1: 3, 2: 1, 6: 1})
>>> second_element
Counter({2: 2, 9: 1, 4: 1, 7: 1})
Again, these are dictionary like objects, so you can check how frequent a specific value appeared directly:
>>> first_element[2]
1
In the first element of your list of tuples, the value 2
appeared 1 time.
Solution 3
You can make count_map, and store the count of each tuple as the value.
>>> count_map = {}
>>> for t in a:
... count_map[t] = count_map.get(t, 0) +1
...
>>> count_map
{(1, 2): 2, (6, 7): 1, (2, 9): 1, (1, 4): 1}
Solution 4
Maybe Dictionary can work better. Because in your code, you are traveling the list for twice. And this makes the complexity of your code O(n^2). And this is not a good thing :)
Best way is the travelling for once and to use 1 or 2 conditions for each traverse. Here is the my first solution for such kind of problem.
a = [(1,2),(1,4),(1,2),(6,7),(2,9)]
dict = {}
for (i,j) in a:
if dict.has_key(i):
dict[i] += 1
else:
dict[i] = 1
print dict
For this code, this will give the output:
{1: 3, 2: 1, 6: 1}
I hope it will be helpful.
Solution 5
Using pandas this is simple and very fast:
import pandas
print(pandas.Series(data=[(1,2),(1,4),(1,2),(6,7),(2,9)]).value_counts())
(1, 2) 2
(1, 4) 1
(6, 7) 1
(2, 9) 1
dtype: int64
DimSarak
Updated on June 09, 2022Comments
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DimSarak over 1 year
I have a list of tuples:
a = [(1,2),(1,4),(1,2),(6,7),(2,9)]
I want to check if one of the individual elements of each tuple matches the same position/element in another tuple, and how many times this occurs.For example: If only the 1st element in some tuples has a duplicate, return the tuple and how many times it's duplicated. I can do that with the following code:
a = [(1,2), (1,4), (1,2), (6,7), (2,9)] coll_list = [] for t in a: coll_cnt = 0 for b in a: if b[0] == t[0]: coll_cnt = coll_cnt + 1 print "%s,%d" %(t,coll_cnt) coll_list.append((t,coll_cnt)) print coll_list
I want to know if there is a more effective way to do this?
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jonrsharpe over 8 yearsYou can also use
collections.defaultdict(int)
to avoid the awkwardget
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doru over 8 yearsThe OP didn't want the number of occurrences of each tuple.
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doru over 8 yearsThe OP didn't want the number of occurrences of each tuple.
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doru over 8 yearsThe OP didn't want the number of occurrences of each tuple.
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Sudipta over 8 years@doru OP's code says otherwise. He/she has calculated counts of all tuples one by one, making it a N^2 operation.
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doru over 8 years@Sudipta have you run the OP code to see the what are the desired results?
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Rick over 8 yearsYou can use
collections.defaultdict(int)
to clean up the inside of the loop a bit -
Sudipta over 8 years@doru- Yes I have done that. OP code is for checking
if only the 1st part of all tuples of the list has a dublicate
. But now OP needs a code to find:if one of the elements of each tuple has a dublicate and how many times
. -
cengineer over 8 yearsYeah, that would clear. But if I use collections, why try to make a loop, right? :) I'd prefer a solution like Andy's one ;)