Python 填充上方/下方 matplotlib 线图
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Filling above/below matplotlib line plot
提问by user1728853
I'm using matplotlib to create a simple line plot. My plot is a simple time-series data set where I have time along the x-axis and the value of something I am measuring on the y-axis. y values can have postitive or negative values and I would like to fill in the area above and below my line with the color blue if the y-value is > 0 and red if the y values is < 0. Here's my plot:
我正在使用 matplotlib 创建一个简单的线图。我的图是一个简单的时间序列数据集，其中我有沿 x 轴的时间和我在 y 轴上测量的值。y 值可以有正值或负值，如果 y 值 > 0，我想用蓝色填充线条上方和下方的区域，如果 y 值 < 0，我想用红色填充。这是我的情节：
As you can see, I can get the blue color to fill in correctly, but I can not get the red color to fill in properly. Here's the basic code I am using:
如您所见，我可以正确填充蓝色，但无法正确填充红色。这是我正在使用的基本代码：
plt.plot(x, y, marker='.', lw=1)
d = scipy.zeros(len(y))
ax.fill_between(xs,ys,where=ys>=d, color='blue')
ax.fill_between(xs,0,where=ys<=d, color='red')
How can I get the area from a positive y-value to the x-axis to be blue and the area from a negative y-value to the x-axis to be red? Thanks for the help.
如何使从正 y 值到 x 轴的区域为蓝色，而从负 y 值到 x 轴的区域为红色？谢谢您的帮助。
采纳答案by sodd
The code snippet you provided should be corrected as follows:
您提供的代码片段应更正如下：
plt.plot(x, y, marker='.', lw=1)
d = scipy.zeros(len(y))
ax.fill_between(xs, ys, where=ys>=d, interpolate=True, color='blue')
ax.fill_between(xs, ys, where=ys<=d, interpolate=True, color='red')
The fill_betweenmethod takes at least two arguments xand y1, while it also has a parameter y2with default value 0. The method will fill the area between y1and y2for the specified x-values.
该fill_between方法至少接受两个参数xand y1，同时它还有一个y2默认值为 0 的参数。该方法将填充指定-valuesy1和之间的区域。y2x
The reason why you didn't get any filling below the x-axis, is due to the fact that you had specified that the fill_betweenmethod should fill the area between y1=0and y2=0, i.e. noarea. To make sure that the fill does not only appear on explicitx-values, specify that the method should interpolate y1as to find the intersections with y2, which is done by specifying interpolate=Truein the method call.
为什么你没有得到的x轴下方的任何填充究其原因，是由于这样的事实，你已指定的fill_between方法应填写之间的区域y1=0和y2=0，即无区域。为确保填充不仅出现在显式x 值上，请指定该方法应进行插值y1以找到与 的交集y2，这是通过interpolate=True在方法调用中指定来完成的。
回答by Thriveth
Try setting the keyword interpolate=True.
尝试设置关键字interpolate=True。
