gr as backend for matplotlib: Can I save images as png?

[floesmrt]

Hi,

I am new to GR. I read on the GR homepage: "... GR can be used as a backend for Matplotlib and significantly improve the performance of existing Matplotlib or PyPlot applications...". Can I use the GR backend to write a png (without using pyplot)? How? Will this be faster than using the agg backend?

I experimented with the sine example form the homepage. If I use it with plt.show(), using the gr backend is about 1.5 times faster than using the tkagg backend. If I naivly replace plt.show() by plt.savefig("test.png") the gr backend is slower than the agg backend. If I have a closer look at what functions are called, I realize that no matter what backend I specify always the file backend_agg.py is used, if I want to save a png.

Thanks Martina

[jheinen]

You can not use the GR backend to write a PNG without using matplotlib.pyplot. The MPLBACKEND environment only redirects the display output to the GR backend - savefig() is handled by MPL itself.

But, you might use the GKS_WSTYPE environment to create the desired output, e.g.

export MPLBACKEND=gr
export GKS_WSTYPE=png
python ...

will create a file gks.png using GR's cairopng driver.

The fastest way to produce figure output with GR is by using the SVG or PDF output (especially for multi-page PDFs), e.g.

export GKS_WSTYPE=svg

will create an SVG file gks.svg.

BTW: If you plan to create a movie, you can use export GKS_WSTYPE=mov with your existing MPL script.

[danielkaiser]

We are closing this issue due to inactivity. Please reopen the issue and let us know if its cause still persists with the current version of GR.