Numpy image - rotate matrix 270 degrees

python matrix image-manipulation numpy
Mikesname picture Mikesname · Mar 17, 2010 · Viewed 17.5k times · Source

I've got a Numpy 2d array that represents a grey-scale image and I need to rotate it 270 degrees. Might be being a bit thick here but the two ways I can find to do this seem quite... circulous:

rotated = numpy.rot90(numpy.rot90(numpy.rot90(orignumpyarray)))

rotated = numpy.fliplr(numpy.flipud(numpy.rot90(orignumpyarray)))

I'm thinking there must be a better way to do this in one operation. Basically a rot270() function? Any ideas?

Answer

Anders Lindahl picture Anders Lindahl · Mar 17, 2010

You can tell rot90 to rotate several times, this should work:

rotated = numpy.rot90(orignumpyarray,3)

Related questions

How to define a two-dimensional array?

I want to define a two-dimensional array without an initialized length like this: Matrix = [][] but it does not work... I've tried the code below, but it is wrong too: Matrix = [5][5] Error: Traceback ... IndexError: list index out of range What is …

Read More
How do I find the length (or dimensions, size) of a numpy matrix in python?

For a numpy matrix in python from numpy import matrix A = matrix([[1,2],[3,4]]) How can I find the length of a row (or column) of this matrix? Equivalently, how can I know the number of rows or columns? So far, the …

Read More
numpy matrix vector multiplication

When I multiply two numpy arrays of sizes (n x n)*(n x 1), I get a matrix of size (n x n). Following normal matrix multiplication rules, a (n x 1) vector is expected, but I simply cannot find any information …

Read More