Counter () count in Python

One: Define a list array to find the number of occurrences of each element in the array

If implemented in Java, is a more complex, need to traverse the array list.

But Python is simple: look at the code

[Python]View Plain Copy

1. A = [1,4,2,3,2,3,4,2]
2. From collections Import Counter
3. Print Counter (a)

Printing results:

Counter ({2:3, 3:2, 4:2, 1:1})

The results show that element 2 appears 3 times, Element 3 appears 2 times, element 4 occurs 2 times, and element 1 appears 1 times.

Second: Find the most frequently occurring elements in an array

Look directly at the code:

[Python]View Plain Copy

1. A = [1,4,2,3,2,3,4,2]
2. From collections Import Counter
3. Print Counter (a). Most_commo (1)

Operation Result:

[(2, 3)]

Continue to modify the code:

[Python]View Plain Copy

1. A = [1,4,2,3,2,3,4,2]
2. From collections Import Counter
3. Print Counter (a)
4. Print Counter (a). Most_common (2)

Operation Result:

[(2, 3), (3, 2)]

Three: summary

(1) The collection class is introduced from the Collections Collection module counter

(2) Counter (a) can print the number of occurrences of each element in Group A

(3) Counter (a). Most_common (2) can print the most frequently occurring elements in the array. The meaning of parameter 2 is that it outputs several elements that have the most occurrences.

Transferred from: http://blog.csdn.net/u013628152/article/details/43198605

Counter () count in Python