如何在numpy ndarray中找到最常使用的字符串元素? [英] how to find most frequent string element in numpy ndarray?

问题描述

他们有什么办法在numpy ndarray中找到最常使用的字符串元素?

Is their any way to find most frequent string element in numpy ndarray?

A= numpy.array(['a','b','c']['d','d','e']])


result should be 'd'

推荐答案

如果您想要一个小数答案，则可以使用np.unique:

If you want a numpy answer you can use np.unique:

>>> unique,pos = np.unique(A,return_inverse=True) #Finds all unique elements and their positions
>>> counts = np.bincount(pos)                     #Count the number of each unique element
>>> maxpos = counts.argmax()                      #Finds the positions of the maximum count

>>> (unique[maxpos],counts[maxpos])
('d', 2)

尽管如果有两个元素具有相同的计数，则这将只是从unique数组中获取第一个元素.

Although if there are two elements with equal counts this will simply take the first from the unique array.

借助此方法，您还可以轻松按元素计数进行排序，如下所示:

With this you can also easily sort by element count like so:

>>> maxsort = counts.argsort()[::-1]
>>> (unique[maxsort],counts[maxsort])
(array(['d', 'e', 'c', 'b', 'a'],
      dtype='|S1'), array([2, 1, 1, 1, 1]))

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