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Python Introduction to NumPy Array Programming Routines in Action

Posted by Mark Chesney
Mark Chesney
11,747 Points

parameter specification for np.repeat()

Why does this code work?

import numpy as np
threes = np.repeat(3, 3)

But these all throw the same error?

threes = np.repeat(3, 3, dtype=np.uint8)  # OK I expected this to fail
threes = np.repeat([3, 3], dtype=np.uint8)
threes = np.repeat((3, 3), dtype=np.uint8)

I ran ?threes and still didn't figure it out.

Thanks!

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,423 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,423 Points

The method np.repeat does not take dtype as an argument. From help(np.repeat):

repeat(a, repeats, axis=None)
    Repeat elements of an array.

    Parameters
    ----------
    a : array_like
        Input array.
    repeats : int or array of ints
        The number of repetitions for each element.  `repeats` is broadcasted
        to fit the shape of the given axis.
    axis : int, optional
        The axis along which to repeat values.  By default, use the
        flattened input array, and return a flat output array.

    Returns
    -------
    repeated_array : ndarray
        Output array which has the same shape as `a`, except along
        the given axis.

So, your first 3 is being treated as an array-like object. Instead, insert the array type you wish:

>>> import numpy as np
>>> np.repeat(3, 3)
array([3, 3, 3])
>>> np.repeat([3], 3)
array([3, 3, 3])
>>> x = np.array(3, dtype=np.uint8)
>>> np.repeat(x, 3)
array([3, 3, 3], dtype=uint8)

Post back if you need more help. Good luck!!

Mark Chesney
Mark Chesney
11,747 Points

Thank you so much Chris! Yes, in hindsight, the CLI returns this error:

TypeError: repeat() got an unexpected keyword argument 'dtype'

I wonder how I'd missed that. My advice to everyone is to try to get plenty of sleep before coding :)