I've currently constructed a plot using rectangle Patches to display a sequence of positions.
EDIT: Code used to generate this (built off of the RLPy library)-
def visualize_trajectory(self, trajectory=[[0,0,0,0], [0.1,0.1,0,0]]):
domain_fig = plt.figure()
for i, s in enumerate(trajectory):
x, y, speed, heading = s[:4]
car_xmin = x - self.REAR_WHEEL_RELATIVE_LOC
car_ymin = y - self.CAR_WIDTH / 2.
car_fig = matplotlib.patches.Rectangle(
[car_xmin,
car_ymin],
self.CAR_LENGTH,
self.CAR_WIDTH,
alpha=(0.8 * i) / len(trajectory) )
rotation = Affine2D().rotate_deg_around(
x, y, heading * 180 / np.pi) + plt.gca().transData
car_fig.set_transform(rotation)
plt.gca().add_patch(car_fig)
Is there any way to overlay each of these patches with images? Ideally, there would be a car image instead of a rectangle at each of the positions.
I've played around with AnnotationBbox and TransformedBbox, but both seem to be inflexible when dealing with rotations.
Take a look at
demo_affine_image
from the matplotlib gallery. It shows how
to rotate an image.
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.transforms as mtransforms
import matplotlib.cbook as cbook
def get_image():
fn = cbook.get_sample_data("necked_tensile_specimen.png")
arr = plt.imread(fn)
# make background transparent
# you won't have to do this if your car image already has a transparent background
mask = (arr == (1,1,1,1)).all(axis=-1)
arr[mask] = 0
return arr
def imshow_affine(ax, z, *args, **kwargs):
im = ax.imshow(z, *args, **kwargs)
x1, x2, y1, y2 = im.get_extent()
im._image_skew_coordinate = (x2, y1)
return im
N = 7
x = np.linspace(0, 1, N)
y = x**1.1
heading = np.linspace(10, 90, N)
trajectory = list(zip(x, y, heading))
width, height = 0.3, 0.3
car = get_image()
fig, ax = plt.subplots()
for i, t in enumerate(trajectory, start=1):
xi, yi, deg = t
im = imshow_affine(ax, car, interpolation='none',
extent=[0, width, 0, height], clip_on=True,
alpha=0.8*i/len(trajectory))
center_x, center_y = width//2, height//2
im_trans = (mtransforms.Affine2D()
.rotate_deg_around(center_x, center_y, deg)
.translate(xi, yi)
+ ax.transData)
im.set_transform(im_trans)
ax.set_xlim(-0.5, 1.5)
ax.set_ylim(-0.5, 1.7)
plt.show()