对箭袋图中的速度信息进行下采样
我有两个数组 (vel_y,vel_z) 分别表示 y 和 z 方向的速度，它们的形状都为 (512,512)，我试图使用颤动图来表示。 以下是我绘制箭袋的方式：
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0,512,num=512)
[X,Y] = np.meshgrid(x,x)
fig, ax = plt.subplots(figsize=(7,7))
ax.quiver(X,Y,vel_y,vel_z,np.arctan2(vel_z,vel_y),pivot='mid',units='x',scale=2)
arctan2() 调用使不同的方向具有不同的颜色，如 这个答案。 显然，绘制所有 5122 这些箭头会导致绘图变得混乱且难以解析，您可以在此处看到： 箭袋图。
我想知道是否有更好的方法来缩放/表示箭头，使其更具可读性？
但是，我遇到的主要问题是如何“缩减采样”此速度信息，例如从绘制 5122 箭头到 1002 。这是否需要在定义速度的点之间进行插值？
谢谢你！
I have two arrays (vel_y,vel_z) representing velocities in the y and z directions, respectively, that are both shaped as (512,512) that I am attempting to represent using a quiver plot.
Here is how I plotted the quiver:
import numpy as np
import matplotlib.pyplot as plt
x = np.linspace(0,512,num=512)
[X,Y] = np.meshgrid(x,x)
fig, ax = plt.subplots(figsize=(7,7))
ax.quiver(X,Y,vel_y,vel_z,np.arctan2(vel_z,vel_y),pivot='mid',units='x',scale=2)
The arctan2() call is so that different orientations are colored differently as in this answer.
Obviously plotting all 5122 of these arrows makes for a jumbled and difficult to parse plot, which you can see here:
Quiver Plot.
I was wondering if there was a better way to scale/represent the arrows so that it is more readable?
However, the main question I have is how I could 'downsample' this velocity information to go from plotting 5122 arrows to 1002 for example. Would this require interpolation between points where the velocity is defined?
Thank you!
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实现此目的的简单方法是在给予颤抖的每个向量中取 N 中的一个点。
对于给定的
np.array，您可以使用以下语法来执行此操作：a[::N]。如果您有多个维度，请在每个维度中重复此操作（您可以为每个维度提供不同的滑动）：a[::N1, ::N2]。在您的情况下：
您不需要插值，除非您想在测量/模拟/其他内容的网格中未定义的点处绘制速度。
The simple way to do this is simply to take one point over N in each vectors given to quiver.
For a given
np.array, you can do this using the following syntax:a[::N]. If you have multiple dimensions, repeat this in each dimension (you can give different slip for each dimension):a[::N1, ::N2].In your case:
You don't need interpolation, unless you want to plot velocities at points not defined in the grid where you have your measurements/simulations/whatever.