NumPy is a scientific and numerical computing extension to the Python programming language.
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votes
0answers
5 views
OpenCV TypeError: contour is not a numpy array, neither a scalar
I'm trying to use OpenCV to extract tags from Nike images. This is a tutorial code taken from:
http://opencv-code.com/tutorials/ocr-ing-nikes-new-rsvp-program/
I've modified few lines of code though ...
4
votes
2answers
13 views
perform varimax rotation in python using numpy
I am working on principal component analysis of a matrix. I have already found the component matrix shown below
A = np.array([[-0.73465832 -0.24819766 -0.32045055]
[-0.3728976 ...
0
votes
1answer
15 views
numpy - multiply each element in array by a scaling factor
I have a numpy array of values, and a list of scaling factors which I want to scale each value in the array by, down each column
values = [[ 0, 1, 2, 3 ],
[ 1, 1, 4, 3 ],
[ 2, 1, ...
0
votes
1answer
23 views
Exclude enpoints in uniform mesh
I would like to create a uniform 1D mesh with N points over an interval of reals (0, pi). Currently I have the following working code:
import numpy as np
u = np.linspace(0, np.pi, N+1, endpoint = ...
5
votes
2answers
53 views
Non-trivial sums of outer products without temporaries in numpy
The actual problem I wish to solve is, given a set of N unit vectors and another set of M vectors calculate for each of the unit vectors the average of the absolute value of the dot product of it with ...
3
votes
1answer
34 views
NaNs in pandas.DataFrame not printing to Excel
I have a pandas.DataFrame which contains numpy.nan floats. When using the Excel writer however, the fields where there should be numpy.nan floats are blank. I would expected at least a string ...
2
votes
2answers
16 views
numpy convert row vector to column vector
matrix1 = np.array([[1,2,3],[4,5,6]])
vector1 = matrix1[:,0] # this should have shape (2,1) but actually has (2,)
matrix2 = np.array([[2,3],[5,6]])
np.hstack((vector1, matrix2))
ValueError: all the ...
2
votes
4answers
77 views
Python Sigma Sums
I have a list of values
x=[1,-1,-1,1,1,-1,1,-1,1,-1]
and I have another blank list
y=[ ]
I am trying to create a function that will take a sigma sum of values in x and store them in y.
For ...
0
votes
2answers
28 views
numpy's loadtxt gives error converting to int when string contains decimal
I'm having trouble trying to load a txt file into a structured array.
Here's a simple example showing the problem.
This works fine:
import numpy as np
from StringIO import StringIO
in1 = ...
0
votes
2answers
38 views
Find all the missing directed edges in an adjacency matrix
I use a numpy matrix to represent a directed graph, like this:
0 0 0
1 0 1
1 0 0
Given such a matrix, I want to find all the missing directed edges for which there exists a directed edge in ...
3
votes
4answers
33 views
How do I combine two numpy arrays element wise in python?
I have two numpy arrays:
A = np.array([1, 3, 5, 7])
B = np.array([2, 4, 6, 8])
and I want to get the following from combining the two:
C = [1, 2, 3, 4, 5, 6, 7, 8]
I'm able to get something ...
3
votes
1answer
31 views
Read a 3d Array from File
Lets say I have a file with the following values:
1 2
3 4
11 12
13 14
and I want to read them as a numpy 2x2x2 array. The standard command np.loadtxt('testfile') reads them in as lots of vectors ...
1
vote
1answer
40 views
Taking up too much memory - python
I wrote a recursive function that exhaustively generates matrices of certain characteristics.
The function is as such:
def heavies(rowSums,colSums,colIndex,matH):
if colIndex == len(colSums) - 1:
...
1
vote
1answer
33 views
Polynomial fitting problems in numpy
I was trying to implement a standard polynomial fitting program, and came across a problem that I could not understand. Here is the code where I have a sample x and y data, which I fit using the ...
3
votes
1answer
26 views
How to invert numpy.roll?
I have a for-loop that repeatedly calls roll and I want to invert the order of the created arrays.
I think I have overlooked some trivial way to do it, but so far I only have found 10000 3 5 ways not ...
