I want to create an empty array and append items to it, one at a time. xs = [] for item in data: xs.append(item) Can I use this list-style notation with NumPy arrays?

However, this is uncommon in python, unless you actually need it for low-level stuff. In most cases, you are better-off using an empty list or empty numpy array, as other answers suggest.

a = numpy.empty(n, dtype=object) This creates an array of length n that can store objects. It can't be resized or appended to. In particular, it doesn't waste space by padding its length. This is …

Jun 5, 2020 · <__array_function__ internals> in concatenate(*args, **kwargs) ValueError: all the input arrays must have same number of dimensions, but the array at index 0 has 2 …

Jul 12, 2011 · I want to define a two-dimensional array without an initialized length like this: Matrix = [][] But this gives an error: IndexError: list index out of range

Aug 23, 2022 · There's no way to say in Python "this variable should never refer to anything other than a list", since Python is dynamically typed. * The default built-in Python type is called a list, …

How to initialize a dict with keys from a list and empty value in Python? Asked 15 years, 9 months ago Modified 2 years, 10 months ago Viewed 530k times

31 In Python, the tendency is usually that one would use a non-fixed size list (that is to say items can be appended/removed to it dynamically). If you followed this, there would be no need to …

Apr 5, 2017 · 129 Build a Python list and convert that to a Numpy array. That takes amortized O (1) time per append + O (n) for the conversion to array, for a total of O (n).

How to initialize a two-dimensional array (list of lists, if not using NumPy) in Python? Asked 15 years, 9 months ago Modified 1 year, 6 months ago Viewed 1.2m times