查找NumPy数组中一个序列的出现次数

序列是由一些元素组成的列表，我们必须找到该序列在一个给定的NumPy数组中出现的次数。这可以通过在ndarray的每一次迭代中检查序列来轻松完成。但是这将导致更多的时间，所以我们使用NumPy方法的概念。

示例 :

Arr = [[2,8,9,4],
       [9,4,9,4],
       [4,5,9,7],
       [2,9,4,3]]
and the seq = [9,4] then output is 4.

Here, 
first row [2,8,9,4] 
contains one [9,4] sequence so output = 1.

second row [9,4,9,4] 
contains two [9,4] sequence so output = 1+2 = 3.

third row [4,5,9,7] 
contains no [9,4] sequence so output = 3+0 = 3.

fourth row [2,9,4,3] 
contains one [9,4] sequence so output = 3+1 = 4.

下面是一个例子的实现。

# importing package
import numpy
  
# create numpy array
arr = numpy.array([[2, 8, 9, 4], 
                   [9, 4, 9, 4],
                   [4, 5, 9, 7],
                   [2, 9, 4, 3]])
  
# Counting sequence
output = repr(arr).count("9, 4")
  
# view output
print(output)

输出 :

4