Concatenate np.arrays python

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How can I do if:

a = np.array([[1,2,3],[5,6,7]])

b = np.array([0,1])

I search to concatenate a and b so as the result would be:

np.array([1,2,3,0],[5,6,7,1])

Thanks a lot

The more numpythonic way to do this is to avoid broadcasting, and use the function designed for this: numpy.column_stack:

np.column_stack([a, b])

array([[1, 2, 3, 0],
       [5, 6, 7, 1]])

numpy.concatenate, Concatenate function that preserves input masks. array_split. Split an array into multiple sub-arrays of equal or near-equal size. split. Concatenate function that preserves input masks. Split an array into multiple sub-arrays of equal or near-equal size. Split array into a list of multiple sub-arrays of equal size. Split array into multiple sub-arrays horizontally (column wise) Split array into multiple sub-arrays vertically (row wise) Split array into multiple sub-arrays along

The problem is to concatenate a horizontally with b as a column vector.

<concat>( |1 2 3|, |0| )
          |5 6 7|  |1|

The concatentation can be done using np.hstack, and b can be converted into a column vector by adding a new axis:

>>> np.hstack([a, b[:, np.newaxis]])
array([[1, 2, 3, 0],
       [5, 6, 7, 1]])

Concatenating two one-dimensional NumPy arrays · python arrays numpy concatenation numpy-ndarray. I have two simple one-dimensional arrays in NumPy. I  numpy.concatenate - Concatenation refers to joining. This function is used to join two or more arrays of the same shape along a specified axis. The function takes the following par

Using numpy broadcast with concatenate

np.concatenate([a,b[:,None]],1)
Out[1053]: 
array([[1, 2, 3, 0],
       [5, 6, 7, 1]])

numpy.concatenate - Concatenation refers to joining. This function is used to join two or more arrays of the same shape along a specified axis. The function  Python offers multiple options to join/concatenate NumPy arrays. Common operations include given two 2d-arrays, how can we concatenate them row wise or column wise. NumPy’s concatenate function allows you to concatenate two arrays either by rows or by columns. Let us see a couple of examples of NumPy’s concatenate function.

refers to joining. This function is used to join two or more arrays of the same shape along a specified axis. numpy.concatenate¶ numpy.concatenate ((a1, a2, ), axis=0, out=None) ¶ Join a sequence of arrays along an existing axis. Parameters a1, a2, … sequence of array_like. The arrays must have the same shape, except in the dimension corresponding to axis (the first, by default). axis int, optional. The axis along which the arrays will be joined.

Joining Arrays Using Stack Functions. Stacking is same as concatenation, the only difference is that stacking is done along a new axis. We can concatenate two 1-  Concatenating objects¶. The concat()function (in the main pandas namespace) does all ofthe heavy lifting of performing concatenation operations along an axis whileperforming optional set logic (union or intersection) of the indexes (if any) onthe other axes.

numpy append uses concatenate under the hood. Append is used for appending the values at the end of the array provided the arrays are of  In Python code, the concatenate function is typically written as np.concatenate(), although you might also see it written as numpy.concatenate(). Either case assumes that you’ve imported the NumPy package with the code import numpy as np or import numpy , respectively.

Comments
  • Oh, I didn't know about that! And it's implemented essentially as @Wen's answer. Fun! :)
  • Yep, column_stack is the only one of the stacking functions (I believe), that converts 1D inputs to 2D columns, so works perfectly here.
  • @Yuca: There is no distinction between a row and a column vector for a 1d array. See e.g. stackoverflow.com/a/42908123/463796 for more on that.
  • @Yuca you can use the transpose with np.atleast_2d: np.hstack([a, np.atleast_2d(b).T]).