python：如何用不同的颜色绘制一条线
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python: how to plot one line in different colors
提问by wuwucat
I have two list as below:
我有两个列表如下：
latt=[42.0,41.978567980875397,41.96622693388357,41.963791391892457,...,41.972407378075879]
lont=[-66.706920989908909,-66.703116557977069,-66.707351643324543,...-66.718218142021925]
now I want to plot this as a line, separate each 10 of those 'latt' and 'lont' records as a period and give it a unique color. what should I do?
现在我想将其绘制为一条线，将这些“latt”和“lont”记录中的每 10 个分开作为一个句点，并为其赋予独特的颜色。我该怎么办？
采纳答案by Joe Kington
There are several different ways to do this. The "best" approach will depend mostly on how many line segments you want to plot.
有几种不同的方法可以做到这一点。“最佳”方法主要取决于您要绘制多少条线段。
If you're just going to be plotting a handful (e.g. 10) line segments, then just do something like:
如果您只是要绘制少量（例如 10 个）线段，那么只需执行以下操作：
import numpy as np
import matplotlib.pyplot as plt
def uniqueish_color():
"""There're better ways to generate unique colors, but this isn't awful."""
return plt.cm.gist_ncar(np.random.random())
xy = (np.random.random((10, 2)) - 0.5).cumsum(axis=0)
fig, ax = plt.subplots()
for start, stop in zip(xy[:-1], xy[1:]):
x, y = zip(start, stop)
ax.plot(x, y, color=uniqueish_color())
plt.show()
If you're plotting something with a million line segments, though, this will be terribly slow to draw. In that case, use a LineCollection. E.g.
但是，如果您要绘制具有一百万条线段的内容，绘制起来会非常缓慢。在这种情况下，请使用LineCollection. 例如
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection
xy = (np.random.random((1000, 2)) - 0.5).cumsum(axis=0)
# Reshape things so that we have a sequence of:
# [[(x0,y0),(x1,y1)],[(x0,y0),(x1,y1)],...]
xy = xy.reshape(-1, 1, 2)
segments = np.hstack([xy[:-1], xy[1:]])
fig, ax = plt.subplots()
coll = LineCollection(segments, cmap=plt.cm.gist_ncar)
coll.set_array(np.random.random(xy.shape[0]))
ax.add_collection(coll)
ax.autoscale_view()
plt.show()
For both of these cases, we're just drawing random colors from the "gist_ncar" coloramp. Have a look at the colormaps here (gist_ncar is about 2/3 of the way down): http://matplotlib.org/examples/color/colormaps_reference.html
对于这两种情况，我们只是从“gist_ncar”颜色放大器中绘制随机颜色。看看这里的颜色图（gist_ncar 大约下降了 2/3）：http://matplotlib.org/examples/color/colormaps_reference.html
回答by blazetopher
See the answer hereto generate the "periods" and then use the matplotlib scatterfunction as @tcaswell mentioned. Using the plot.holdfunction you can plot each period, colors will increment automatically.
请参阅此处的答案以生成“句点”，然后使用@tcaswell 提到的matplotlib 分散函数。使用plot.hold函数可以绘制每个周期，颜色会自动增加。
回答by ali_m
Copied from this example:
从这个例子复制：
import numpy as np
import matplotlib.pyplot as plt
from matplotlib.collections import LineCollection
from matplotlib.colors import ListedColormap, BoundaryNorm
x = np.linspace(0, 3 * np.pi, 500)
y = np.sin(x)
z = np.cos(0.5 * (x[:-1] + x[1:])) # first derivative
# Create a colormap for red, green and blue and a norm to color
# f' < -0.5 red, f' > 0.5 blue, and the rest green
cmap = ListedColormap(['r', 'g', 'b'])
norm = BoundaryNorm([-1, -0.5, 0.5, 1], cmap.N)
# Create a set of line segments so that we can color them individually
# This creates the points as a N x 1 x 2 array so that we can stack points
# together easily to get the segments. The segments array for line collection
# needs to be numlines x points per line x 2 (x and y)
points = np.array([x, y]).T.reshape(-1, 1, 2)
segments = np.concatenate([points[:-1], points[1:]], axis=1)
# Create the line collection object, setting the colormapping parameters.
# Have to set the actual values used for colormapping separately.
lc = LineCollection(segments, cmap=cmap, norm=norm)
lc.set_array(z)
lc.set_linewidth(3)
fig1 = plt.figure()
plt.gca().add_collection(lc)
plt.xlim(x.min(), x.max())
plt.ylim(-1.1, 1.1)
plt.show()
回答by tacaswell
Cribbing the color choice off of @JoeKington,
抄袭@JoeKington 的颜色选择，
import numpy as np
import matplotlib.pyplot as plt
def uniqueish_color(n):
"""There're better ways to generate unique colors, but this isn't awful."""
return plt.cm.gist_ncar(np.random.random(n))
plt.scatter(latt, lont, c=uniqueish_color(len(latt)))
You can do this with scatter.
您可以使用scatter.
