How do I convert a numpy matrix into a boolean matrix?

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I have a n x n matrix in numpy which has 0 and non-0 values. Is there a way to easily convert it to a boolean matrix?

Thanks.

numpy.array(old_matrix, dtype=bool)

Alternatively,

old_matrix != 0

The first version is an elementwise coercion to boolean. Analogous constructs will work for conversion to other data types. The second version is an elementwise comparison to 0. It involves less typing, but ran slightly slower when I timed it. Which you use is up to you; I'd probably decide based on whether "convert to boolean" or "compare to 0" is a better conceptual description of what I'm after.

Boolean Masking of Arrays, import numpy as np A = np.array([4, 7, 3, 4, 2, 8]) print(A == 4). [ True False False True False False]. Every element of the Array A is tested, if it is equal to 4. The NOT or tilde (~) operator inverts each of the Boolean values in a NumPy array. The inverted Boolean array can then be passed to the ‘np.where’ function. Ok, that was a long, tiring explanation. Let’s see this thing in action.

You should use array.astype(bool) (or array.astype(dtype=bool)). Works with matrices too.

numpy, A boolean array can be created manually by using dtype=bool when creating the array. Values other than 0 , None , False or empty strings are considered True. Convert a 2D Numpy array to 1D array using numpy.reshape() Python’s numpy module provides a built-in function reshape() to convert the shape of a numpy array, numpy.reshape(arr, newshape, order=’C’) It accepts following arguments, a: Array to be reshaped, it can be a numpy array of any shape or a list or list of lists.

Simply use equality check:

Suppose a is your numpy matrix, use b = (a == 0) or b = (a != 0) to get the boolean value matrix.

In some case, since the value maybe sufficiently small but non-zero, you may use abs(a) < TH, where TH is the numerical threshold you set.

numpy.ndarray.astype — NumPy v1.13 Manual, This is documentation for an old release of NumPy (version 1.13.0). Read this page Typecode or data-type to which the array is cast. subok : bool, optional. I have a 3d numpy array u, shape (k, m, n), and I am trying to compute a new array uprod, shape (k, m, n), such that uprod[j] = np.dot(A, u[j]), where A is a fixed matrix that doesn't depend on j at all. I can easily do this writing a loop over the inner-most index, but is there a faster/better way to do so?

.astype(dtype)

https://docs.scipy.org/doc/numpy-1.13.0/reference/generated/numpy.ndarray.astype.html

It's nice that this will work on binary-like floats including 0. and 1..

old_matrix.astype(bool)

Boolean numpy arrays — MTH 337, A boolean array is a numpy array with boolean (True/False) values. Such array can be obtained by applying a logical operator to another� To create a NumPy array, you can use the function np.array(). All you need to do to create a simple array is pass a list to it. If you choose to, you can also specify the type of data in your list. You can find more information about data types here. >>>

Python : Create boolean Numpy array with all True or all False or , Converting a List to bool Numpy array. Convert a list of integers to boolean numpy array. # List of� Array Scalars¶. Numpy generally returns elements of arrays as array scalars (a scalar with an associated dtype). Array scalars differ from Python scalars, but for the most part they can be used interchangeably (the primary exception is for versions of Python older than v2.x, where integer array scalars cannot act as indices for lists and tuples).

numpy.matrix — NumPy v1.19 Manual, dtypedata-type. Data-type of the output matrix. copybool. If data is already an ndarray Insert scalar into an array (scalar is cast to array's dtype, if possible). Convert 1D Numpy array to a 2D numpy array along the column. In the previous example, when we converted a 1D array to a 2D array or matrix, then the items from input array will be read row wise i.e.

4. NumPy Basics: Arrays and Vectorized Computation, In addition to np.array , there are a number of other functions for creating new arrays. asarray, Convert input to ndarray, but do not copy if the input is already an ndarray This boolean array can be passed when indexing the array: In [88]: � Given a boolean value(s), write a Python program to convert them into an integer value or list respectively. Given below are a few methods to solve the above task. Method #1: Using int() method

Comments
  • Do the zero values need to be set to false? Or is there another condition?
  • Thanks for this will go with the faster one - the matrix will be quite large and sparse