python:重複numpy陣列的每个元素5次

In [1]: data = np.arange(-50,50,10)

要重複每个元素5次，請使用np.repeat：

In [3]: np.repeat(data, 5)
Out[3]: 
array([-50, -50, -50, -50, -50, -40, -40, -40, -40, -40, -30, -30, -30,
       -30, -30, -20, -20, -20, -20, -20, -10, -10, -10, -10, -10,   0,
         0,   0,   0,   0,  10,  10,  10,  10,  10,  20,  20,  20,  20,
        20,  30,  30,  30,  30,  30,  40,  40,  40,  40,  40])

要重複陣列5次，請使用np.tile：

In [2]: np.tile(data, 5)
Out[2]: 
array([-50, -40, -30, -20, -10,   0,  10,  20,  30,  40, -50, -40, -30,
       -20, -10,   0,  10,  20,  30,  40, -50, -40, -30, -20, -10,   0,
        10,  20,  30,  40, -50, -40, -30, -20, -10,   0,  10,  20,  30,
        40, -50, -40, -30, -20, -10,   0,  10,  20,  30,  40])

---

但是，請註意，有時您可以利用NumPy廣播，而不用建立具有重複元素的更大陣列.

例如，如果

z = np.array([1, 2])
v = np.array([[3], [4], [5]])

然後添加這些陣列以产生

[[4 5]
  [5 6]
  [6 7]]

您不需要使用圖塊：

In [12]: np.tile(z, (3,1))
Out[12]: 
array([[1, 2],
       [1, 2],
       [1, 2]])
In [13]: np.tile(v, (1,2))
Out[13]: 
array([[3, 3],
       [4, 4],
       [5, 5]])
In [14]: np.tile(z, (3,1)) + np.tile(v, (1,2))
Out[14]: 
array([[4, 5],
       [5, 6],
       [6, 7]])

相反，NumPy將為您廣播陣列：

In [15]: z + v
Out[15]: 
array([[4, 5],
       [5, 6],
       [6, 7]])

只需使用 np.repeat ：

In [5]: data.repeat(5)
Out[5]: 
array([-50, -50, -50, -50, -50, -40, -40, -40, -40, -40, -30, -30, -30,
       -30, -30, -20, -20, -20, -20, -20, -10, -10, -10, -10, -10,   0,
         0,   0,   0,   0,  10,  10,  10,  10,  10,  20,  20,  20,  20,
        20,  30,  30,  30,  30,  30,  40,  40,  40,  40,  40])