[Numpy-discussion] Matrix operation.

2010-04-02 Thread gerardob
Let A be a square matrix of 0's and 1's, and let X be a one dimesional vector. The length of X is equal to the number of 1's that A has. I would like to produce a new matrix B by traversing the matrix A row by row and: 1- whenever i find a 0, set B in that position to zero. 2- whenever i find a

Re: [Numpy-discussion] Matrix operation.

2010-04-02 Thread Shailendra
A=[[1,1,0], ... [1,0,0], ... [0,0,1]] X=[2,9,10,3] import numpy A=numpy.asarray(A) X=numpy.asarray(X) A array([[1, 1, 0], [1, 0, 0], [0, 0, 1]]) X array([ 2, 9, 10, 3]) non_zero=numpy.nonzero(A) non_zero (array([0, 0, 1, 2]), array([0, 1, 0, 2])) A[non_zero] array([1, 1,

Re: [Numpy-discussion] Matrix operation.

2010-04-02 Thread Vicente Sole
With A and X being arrays: B=numpy.zeros(A.shape, A.dtype) B[A0] = X Armando Quoting gerardob gberbeg...@gmail.com: Let A be a square matrix of 0's and 1's, and let X be a one dimesional vector. The length of X is equal to the number of 1's that A has. I would like to produce a new

[Numpy-discussion] matrix operation

2010-03-17 Thread gerardob
Let A and B be two n x n matrices. I would like to have another n x n matrix C such that C_ij = min {A_ij, B_ij} Example: A = numpy.array([[2,3],[10,12]]) B = numpy.array([[1,4],[9,13]]) Output C = [[1,3],[9,12]] The function min(axis) of numpy seems to be only unary. Thanks. -- View

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Ian Mallett
import numpy A = numpy.array([[2,3],[10,12]]) B = numpy.array([[1,4],[9,13]]) C = numpy.array([A,B]) numpy.min(C,0) array([[ 1, 3], [ 9, 12]]) Ian ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Ernest Adrogué
17/03/10 @ 11:47 (-0700), thus spake gerardob: Let A and B be two n x n matrices. I would like to have another n x n matrix C such that C_ij = min {A_ij, B_ij} Example: A = numpy.array([[2,3],[10,12]]) B = numpy.array([[1,4],[9,13]]) Output C = [[1,3],[9,12]] The function

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Keith Goodman
On Wed, Mar 17, 2010 at 11:47 AM, gerardob gberbeg...@gmail.com wrote: Let A and B be two n x n matrices. I would like to have another n x n  matrix C such that C_ij = min {A_ij, B_ij} Example: A = numpy.array([[2,3],[10,12]]) B = numpy.array([[1,4],[9,13]]) Output C = [[1,3],[9,12]]

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Eric Firing
gerardob wrote: Let A and B be two n x n matrices. I would like to have another n x n matrix C such that C_ij = min {A_ij, B_ij} Example: A = numpy.array([[2,3],[10,12]]) B = numpy.array([[1,4],[9,13]]) Output C = [[1,3],[9,12]] The function min(axis) of numpy seems to be only

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Christopher Barker
gerardob wrote: Let A and B be two n x n matrices. I would like to have another n x n matrix C such that C_ij = min {A_ij, B_ij} In [30]: A = numpy.array([[2,3],[10,12]]) In [31]: B = numpy.array([[1,4],[9,13]]) In [32]: numpy.minimum(A,B) Out[32]: array([[ 1, 3], [ 9, 12]])

Re: [Numpy-discussion] matrix operation

2010-03-17 Thread Christopher Barker
Christopher Barker wrote: In [32]: numpy.minimum(A,B) wow! fifth to answer that one -- darn I'm slow! -Chris -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/ORR(206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA

[Numpy-discussion] matrix operation.

2010-03-15 Thread gerardo.berbeglia
I have another matrix operations which seems a little more complicated. Let A be an n x n matrix and let S be a subset of {0,...,n-1}. Assume S is represented by a binary vector s, with a 1 at the index i if i is in S. (e.g. if S={0,3} then s = [1,0,0,1]) I re-post the question because the

[Numpy-discussion] matrix operation

2010-03-12 Thread gerardo.berbeglia
Hello, I want to divide an n x n (2-dimension) numpy array matrix A by a n (1-dimension) array d as follows: Take n = 2. Let A= 2 3 1 10 and let d = [ 3 2 ] Then i would like to have A/d = 2/3 3/3 1/2 10/2 This is to avoid loops to

Re: [Numpy-discussion] matrix operation

2010-03-12 Thread Robert Kern
On Fri, Mar 12, 2010 at 12:52, gerardo.berbeglia gberbeg...@gmail.com wrote: Hello, I want to divide an n x n (2-dimension) numpy array matrix A by a n (1-dimension) array d as follows: Take n = 2. Let A=   2 3           1 10 and let d = [ 3 2 ] Then i would like to have A/d = 2/3  3/3