Repeat Different Elements Of An Array Different Amounts Of Times

Say I have an array with longitudes, lonPorts lonPort =np.loadtxt('LongPorts.txt',delimiter=',') for example: lonPort=[0,1,2,3,...] And I want to repeat each element a different

Solution 1:

You can use np.repeat():

np.repeat(a, [5,3,2,3])

Example:

In [3]: a = np.array([0,1,2,3])

In [4]: np.repeat(a, [5,3,2,3])
Out[4]: array([0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 3, 3])

Solution 2:

Without relying on numpy, you can create a generator that will consume your items one by one, and repeat them the desired amount of time.

x = [0, 1, 2, 3]
repeat = [4, 3, 2, 1]

def repeat_items(x, repeat):
  for item, r in zip(x, repeat):
    while r > 0:
      yield item
      r -= 1for value in repeat_items(x, repeat):
  print(value, end=' ')

displays 0 0 0 0 1 1 1 2 2 3.

Solution 3:

Providing a numpy-free solution for future readers that might want to use lists.

>>>lst = [0,1,2,3]>>>repeat = [5, 3, 2, 3]>>>[x for sub in ([x]*y for x,y inzip(lst, repeat)) for x in sub]
[0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 3, 3]

If lst contains mutable objects, be aware of the pitfalls of sequence multiplication for sequences holding mutable elements.