为什么没有图片显示 [英] why does no picture show

问题描述

from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg
if __name__ == "__main__":
    fig1 = ...
    print("start plotting")
    canvas = FigureCanvasQTAgg(fig1)
    canvas.draw()
    canvas.show()

我已经写了一个返回matplotlib.figure对象的函数。我已经运行了上面的脚本。它使Python崩溃了。我该怎么做？

I have written to function which returns a matplotlib.figure object. I have run the above script. It has crashed Python. How do I do this?

我使用FigureCanvasQTAgg和matplotlib.figure而不是使用matplotlib.pyplot的原因是Figure对象还允许我做某事像

The reasons I have worked with FigureCanvasQTAgg and matplotlib.figure instead of working with matplotlib.pyplot is that the Figure object also allow me to do something like

with PdfPages(...) as pdf_writer:
    canvas = FigureCanvasPDF(fig1)
    pdf_writer.savefig(fig1)
    pdf_writer.savefig(fig1)

写出两个副本单个pdf文件中的同一图。另外，它还允许我将多个图形写入同一PDF。我不知道有什么方法可以仅使用matplotlib.pyplot

which writes out two copies of the same figure in a single pdf file. Also it would allow me to write write multiple figures into the same PDF. I am unaware of any way we can do this using only matplotlib.pyplot

推荐答案

显示图中最简单，最佳的方法matplotlib将使用pyplot界面：

The easiest and best way to show a figure in matplotlib is to use the pyplot interface:

import matplotlib.pyplot as plt
fig1= plt.figure()
plt.show()

要以pdf文件的形式创建输出，您可以d：

For creating the output in the form of a pdf file, you'd use:

import matplotlib.pyplot as plt
fig1= plt.figure()
plt.savefig("filename.pdf")

如果要将多个图形保存到同一pdf文件，请使用 matplotlib.backends.backend_pdf.PdfPages（ output.pdf）

If you want to save multiple figures to the same pdf file, use matplotlib.backends.backend_pdf.PdfPages("output.pdf")

import matplotlib.pyplot as plt
import matplotlib.backends.backend_pdf

fig1= plt.figure()
ax=fig1.add_subplot(111)

outfile = "output.pdf"
with matplotlib.backends.backend_pdf.PdfPages(outfile) as pdf_writer:
    pdf_writer.savefig(fig1)
    pdf_writer.savefig(fig1)

如何保存通过同一函数创建的多个图形的完整示例将是是

A complete example of how to save multiple figures created from the same function would be

import matplotlib.pyplot as plt
import matplotlib.backends.backend_pdf

def plot(data):
    fig= plt.figure()
    ax = fig.add_subplot(111)
    ax.plot(data)
    return fig

fig1 = plot([1,2,3])
fig2 = plot([9,8,7])

outfile = "output.pdf"
with matplotlib.backends.backend_pdf.PdfPages(outfile) as pdf_writer:
    pdf_writer.savefig(fig1)
    pdf_writer.savefig(fig2)

FigureCanvasQTAgg 是要在PyQt GUI中使用的，如果要使用它，则需要先创建它。 此问题向您展示了如何执行此操作，但似乎仅显示或保存该图形就有些过分了。

FigureCanvasQTAgg is meant to be used in a PyQt GUI, which you will need to create first, if you want to use that. This question shows you how to do that but it seems a bit of an overkill for just showing or saving the figure.

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