Repeating each element of a numpy array 5 times
In [1]: data = np.arange(-50,50,10)
To repeat each element 5 times use 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])
To repeat the array 5 times use 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])
Note, however, that sometimes you can take advantage of NumPy broadcasting instead of creating a larger array with repeated elements.
For example, if
z = np.array([1, 2])v = np.array([[3], [4], [5]])
then to add these arrays to produce
[[4 5] [5 6] [6 7]]
you do not need to use tile:
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]])
Instead, NumPy will broadcast the arrays for you:
In [15]: z + vOut[15]: array([[4, 5], [5, 6], [6, 7]])
Simply use 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])