James Mallett - 1 year ago 80
Python Question

# Python Numpy generate coordinates for X and Y values in a certain range

I am trying to generate an array of coordinates that will lie on an image.
The image being used is a 640x480 pixel frame. I have been able to make an array of all the x and y points that I wish to use. I am trying to plot small circles at each of these points just for visualization and for later use so I am trying to get the coordinates into a form that can be entered into the OpenCV circle function. Below is what I have got so far:

``````Ypts = np.arange(5, 480, 5)
Xpts = np.arange(5, 640, 5)
``````

I have tried using

``````[pts]= np.vstack([Xpts, Ypts]).T
``````

and

``````coordinate = []
for x in range(Xpts.size):
for y in range(Ypts.size):
coordinate.append((x, y))
``````

With no success, the output I get for coordinate is
`[0, 0], [0, 1], [0, 2], ...`
instead of points relating to the values of
`Xpts`
and
`Ypts`
.

On a smaller scale this is an example of what the x and y arrays are:

``````Xpts = [5, 10, 15, 20, 25, 30, 35]
Ypts = [5, 10, 15]
``````

and what i am trying to get to as an answer is:

``````Points = [[5, 5],
[5, 10],
[5, 15],
[10, 5],
[10, 10],
[10, 15],
[15, 5],
[15, 10],
......,
[35, 15]]
``````

You can use `itertools.product` which will basically return all possible combinations of the provided lists. See this code for an example:

``````import numpy as np
import itertools

Xpts=[5, 10, 15, 20, 25, 30, 35]
Ypts=[5, 10, 15]

Points = np.array(list(itertools.product(Xpts, Ypts)))
``````

This will return the following:

``````array([[ 5,  5],
[ 5, 10],
[ 5, 15],
[10,  5],
[10, 10],
[10, 15],
[15,  5],
[15, 10],
[15, 15],
[20,  5],
[20, 10],
[20, 15],
[25,  5],
[25, 10],
[25, 15],
[30,  5],
[30, 10],
[30, 15],
[35,  5],
[35, 10],
[35, 15]])
``````
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