Issue
I want to read a list of images into Python/Matplotlib and then plot this images instead of other markers (like points) in a graph. I have tried with imshow but I didn't succeed, because I cannot shift the image to another position and scale it appropriately. Maybe somebody has a good idea : )
Solution
There are two ways to do this.
- Plot the image using
imshow
with theextent
kwarg set based on the location you want the image at. - Use an
OffsetImage
inside anAnnotationBbox
.
The first way is the easiest to understand, but the second has a large advantage. The annotation box approach will allow the image to stay at a constant size as you zoom in. Using imshow
will tie the size of the image to the data coordinates of the plot.
Here's an example of the second option:
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.offsetbox import OffsetImage, AnnotationBbox
from matplotlib.cbook import get_sample_data
def main():
x = np.linspace(0, 10, 20)
y = np.cos(x)
image_path = get_sample_data('ada.png')
fig, ax = plt.subplots()
imscatter(x, y, image_path, zoom=0.1, ax=ax)
ax.plot(x, y)
plt.show()
def imscatter(x, y, image, ax=None, zoom=1):
if ax is None:
ax = plt.gca()
try:
image = plt.imread(image)
except TypeError:
# Likely already an array...
pass
im = OffsetImage(image, zoom=zoom)
x, y = np.atleast_1d(x, y)
artists = []
for x0, y0 in zip(x, y):
ab = AnnotationBbox(im, (x0, y0), xycoords='data', frameon=False)
artists.append(ax.add_artist(ab))
ax.update_datalim(np.column_stack([x, y]))
ax.autoscale()
return artists
main()
Answered By - Joe Kington
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