警告：PyPlot正在使用tkagg后端，这会导致M上的崩溃

Question

有人知道如何在Julia中将backend的PyPlot从"TkAgg"改成Qt5Agg吗？你知道吗

当我尝试在Julia中Using PyPlot时，得到了这个警告：

julia> using PyPlot
[ Info: Recompiling stale cache file /Users/tonyspc/.julia/compiled/v1.2/PyPlot/oatAj.ji for PyPlot [d330b81b-6aea-500a-939a-2ce795aea3ee]
┌ Warning: PyPlot is using tkagg backend, which is known to cause crashes on MacOS (#410); use the MPLBACKEND environment variable to request a different backend.
└ @ PyPlot ~/.julia/packages/PyPlot/4wzW1/src/init.jl:192

我尝试使用这里发布的解决方案：https://github.com/JuliaPy/PyPlot.jl/issues/454

但它失败了：

julia> using PyCall
[ Info: Recompiling stale cache file /Users/tonyspc/.julia/compiled/v1.2/PyCall/GkzkC.ji for PyCall [438e738f-606a-5dbb-bf0a-cddfbfd45ab0]

julia> pyimport_conda("PyQt5", "pyqt")
ERROR: PyError (PyImport_ImportModule

The Python package PyQt5 could not be found by pyimport. Usually this means
that you did not install PyQt5 in the Python version being used by PyCall.

PyCall is currently configured to use the Python version at:

/System/Library/Frameworks/Python.framework/Versions/2.7/Resources/Python.app/Contents/MacOS/Python

and you should use whatever mechanism you usually use (apt-get, pip, conda,
etcetera) to install the Python package containing the PyQt5 module.

One alternative is to re-configure PyCall to use a different Python
version on your system: set ENV["PYTHON"] to the path/name of the python
executable you want to use, run Pkg.build("PyCall"), and re-launch Julia.

Another alternative is to configure PyCall to use a Julia-specific Python
distribution via the Conda.jl package (which installs a private Anaconda
Python distribution), which has the advantage that packages can be installed
and kept up-to-date via Julia.  As explained in the PyCall documentation,
set ENV["PYTHON"]="", run Pkg.build("PyCall"), and re-launch Julia. Then,
To install the PyQt5 module, you can use `pyimport_conda("PyQt5", PKG)`,
where PKG is the Anaconda package the contains the module PyQt5,
or alternatively you can use the Conda package directly (via
`using Conda` followed by `Conda.add` etcetera).

) <type 'exceptions.ImportError'>
ImportError('No module named PyQt5',)

Stacktrace:
 [1] pyimport(::String) at /Users/tonyspc/.julia/packages/PyCall/ttONZ/src/PyCall.jl:544
 [2] pyimport_conda(::String, ::String, ::String) at /Users/tonyspc/.julia/packages/PyCall/ttONZ/src/PyCall.jl:702
 [3] pyimport_conda(::String, ::String) at /Users/tonyspc/.julia/packages/PyCall/ttONZ/src/PyCall.jl:701
 [4] top-level scope at REPL[4]:1

但是我已经用brew install pyqt安装了PyQt5

我不知道为什么我的matplot library位于python2目录而不是python3目录：

julia> pyimport("matplotlib").matplotlib_fname()
"/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/matplotlib/mpl-data/matplotlibrc"

我在Mac上有默认的python2，并使用Homebrew安装了python3

MacBook-Pro:~ tonyspc$ which python3
/usr/local/bin/python3
MacBook-Pro:~ tonyspc$ which python
/usr/bin/python

我应该将ENV["PYTHON"]设置为"/usr/local/bin/python3"吗？你知道吗

Answer 1

我遇到了类似的问题，我将此添加到.bashrc中，以便每次都运行：

export MPLBACKEND=qt5agg

然后在执行]build PyCall PyPlot并重新启动julia之后，它似乎找到了正确的后端来进行绘图。你知道吗

我打开的相关问题（以及我得到的答案）：https://github.com/JuliaPy/PyPlot.jl/issues/453#issuecomment-527163934

Answer 2

尝试在一个新的REPL中设置ENV["PYTHON"] = "/usr/local/bin/python3"，后跟pkg> build PyCall PyPlot。这应该使PyCall（因此也是PyPlot）使用本地python3。你知道吗