Altair图书馆|难以将图表保存为.png

如何解决Altair图书馆|难以将图表保存为.png

我正在尝试将altair图表保存为.png，但是我却收到以下错误。您能帮我吗，我不知道我在做什么错。

有关信息，我设法将图形保存为.html和.json格式，但是.png，.jpeg和.svg均不起作用。我已经尝试安装altair_saver并返回Requirement already satisfied。

谢谢您的帮助。

>>> plot.save('src/modality.png')
Traceback (most recent call last):
  File "<stdin>",line 1,in <module>
  File "/app/installer/envPySpark/lib/python3.6/site-packages/altair/vegalite/v4/api.py",line 476,in save
    result = save(**kwds)
  File "/app/installer/envPySpark/lib/python3.6/site-packages/altair/utils/save.py",line 121,in save
    **kwargs,File "/app/installer/envPySpark/lib/python3.6/site-packages/altair/utils/mimebundle.py",line 60,in spec_to_mimebundle
    return altair_saver.render(spec,format,mode=mode,**kwargs)
  File "/app/installer/envPySpark/lib/python3.6/site-packages/altair_saver/_core.py",line 255,in render
    Saver = _select_saver(method,fmt=fmt)
  File "/app/installer/envPySpark/lib/python3.6/site-packages/altair_saver/_core.py",line 69,in _select_saver
    raise ValueError(f"No enabled saver found that supports format={fmt!r}")
ValueError: No enabled saver found that supports format='png'

---

更新

使用我的conda env运行此命令行后

$ conda install -c conda-forge altair_saver

出现新错误：

>>> plot.save('src/modality.png')
TypeError: Cannot read property 'getContext' of null
    at resize (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-scenegraph/build/vega-scenegraph.js:3377:26)
    at CanvasRenderer.prototype$6.resize (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-scenegraph/build/vega-scenegraph.js:3427:5)
    at CanvasRenderer.prototype$4.initialize (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-scenegraph/build/vega-scenegraph.js:2989:17)
    at CanvasRenderer.prototype$6.initialize (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-scenegraph/build/vega-scenegraph.js:3422:28)
    at initializeRenderer (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-view/build/vega-view.js:630:8)
    at renderHeadless (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-view/build/vega-view.js:736:12)
    at processticksAndRejections (internal/process/task_queues.js:93:5)
    at async View.renderToCanvas [as toCanvas] (/export/home/cgilles/.user_conda/miniconda/envs/metrologie/lib/vega-cli/node_modules/vega-view/build/vega-view.js:771:15)

解决方法

为了将图表另存为PNG，您需要安装t，以及nodejs或硒后端所需的其他依赖项。详细信息请参见：https://github.com/altair-viz/altair_saver#installation