Python：如何计算元组列表中的出现次数？

Question

I have a list of tuples , with each tuple having two elements: an integer and an inner list. The list of tuples has len=900 and each inner list can have len=2 , len=3 , or len=4 depending on the case being.

This is an excerpt of the list:

mylist=[(0, [1.0, 1.0]), (1, [1.0, 1.0, 1.0]), ..., (31, [1.0, 1.0, 1.0, 1.0]), ...] .

This is a specific case in which each element of the inner lists is 1.0 , but I want to deal with the generic case featuring different values.

My questions:

1) How can I count the total number of elements within the inner lists? In the visualized example this number would be 2+3+4=9 .

2) How can I count the occurrences of each value (or, better, of each bin ) within the inner lists?

Answer 1

Here's something to get you started. For #1, you can get the lengths of each part of the tuples with a list comprehension:

lens = [len(y) for x, y in mylist]

This will generate an array of the lengths of each sublist in the tuples, so lens[0] will equal 2, etc.

Answer 2

You just iterate through the list then iterate through the inner list and you create a dictionnary to count each value separately. Also you increment for each innerlist a variable to count the elements.

inner_list_count = 0
value_count = dict()
for key,innerlist in mylist:
    inner_list_count += len(innerlist)
    for value in innerlist:
        if value not in value_count:
            value_count(value) = 0
        value_count(value) += 1

Answer 3

Number of elements:

sum(len(l) for _, l in mylist)

Number of occurrences:

from collections import Counter
Counter(x for _, l in mylist for x in l)

Occurrences binned:

from collections import Counter
binsize = 100
Counter(x - x % binsize for _, l in mylist for x in l)