NumPy

If you want to get a 1-D array of a multi-dimensional array, try np.ravel(arr). You can either read the elements in the same row first or read the elements in the same column first.
Find an example of the np.ravel method above.
Link to the source code.

If you want to change the positions of rows or columns in a Numpy array, simply use a list to specify the new positions as shown above.

If you want to get the row whose ALL values satisfy a certain condition, use numpy’s all method. To get the row whose AT LEAST one value satisfies a certain condition, use numpy’s any method.
The code above shows the difference in outputs between all and any.

If you want to replace elements of a NumPy array based on a condition, use np.where. The code above shows how it works.

Link to the source code.

If you want to get the index of the sorted list for the original list, apply np.argsort() twice. In the example, 1 is the smallest value so it is indexed 0. 2 is the second-largest value to it is indexed 1.

To get the index of the max value in a Numpy array, use np.argmax. Below is an example.
This can be helpful to get the highest probability in an array of probabilities.