Meshgrid
Numpy meshgrid creates grid matrices from the input arrays. These matrices are also called coordinate matrices.
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| figure: From microsoft excel. Showing good example of meshgrid. |
a = np.arange(5)
X, Y = np.meshgrid(a, a)
X
array([[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4],
[0, 1, 2, 3, 4]])
Y
array([[0, 0, 0, 0, 0],
[1, 1, 1, 1, 1],
[2, 2, 2, 2, 2],
[3, 3, 3, 3, 3],
[4, 4, 4, 4, 4]])These matrices allow to make all the possible combinations for the input arrays elements. We can do this by placing these x and y matrices on top one another.
for i in a:
for j in a:
print((X[i,j], Y[i,j]))
(0, 0)
(1, 0)
(2, 0)
(3, 0)
(4, 0)
(0, 1)
(1, 1)
(2, 1)
(3, 1)
(4, 1)
(0, 2)
(1, 2)
(2, 2)
(3, 2)
(4, 2)
(0, 3)
(1, 3)
(2, 3)
(3, 3)
(4, 3)
(0, 4)
(1, 4)
(2, 4)
(3, 4)
(4, 4)Note
Using Uppercase variable name for output return from
meshgridis usually a preferred, given using small case in python conventions.
By default np.meshgrid uses Cartesian system for indexing ( system). This can be changed to matrix indexing .
np.meshgrid([1, 2], [4, 5])
[array([[1, 2],
[1, 2]]),
array([[4, 4],
[5, 5]])]
np.meshgrid([1, 2], [4, 5], indexing="ij")
[array([[1, 1],
[2, 2]]),
array([[4, 5],
[4, 5]])]Applications for Meshgrid
- Meshgrid is used to create coordinate matrices to model a grid.
- Model 2D mathematical functions.
- etc.
Refer notebook.