Tutorial: automatically export vector graphic (PDF) from plotly plot

Question

Recently I was wondering whether it was possible to automatically export plots from plotly. Unfortunately plotly's documentation is a joke and the module wants you to pay for a feature as basic as this. In the free version only automatic exports in non-vector formats (png) is possible. Here I want to present a workaround relying on phantomjs.

Answer 1

Step 1: Generate html file

import plotly.offline as py
import plotly.graph_objs as go

data = go.Scatter(x=[i for i in range(10)],
                  y=[i**2 for i in range(10)],
                  mode='lines')
layout = go.Layout(title="First Plot",
                   xaxis={'title':'x - axis'},
                   yaxis={'title':'y - axis'})
fig = dict(data=[data], layout=layout)

py.plot(fig,
        filename='temp.html',
        include_plotlyjs=True,
        output_type='file'
       )

Note: This includes a great part of plotly.js into the html file. This alone takes up some 2 MB. If need be, change include_plotlyjs to False and reference plotly.js inside the html file:

<script src="path/to/plotly.js"></script>

Step 2: Script for PhantomJS

Write a javascript file for phantomjs for exporting the PDF file:

var page = require('webpage').create();
var system = require('system');
var args = system.args;

page.viewportSize = { width: args[3], height: args[4] };
page.clipRect = { top: 0, left: 0, width: args[3], height: args[4] };

page.open(args[1], function() {
  page.render(args[2]);
  phantom.exit();
});

this expects 4 parameters: The path to the html file, the output file path, width and height of the output file.

Step3: Call PhantomJS script from python

import subprocess

xSize = 1280
ySize = 1024
subprocess.check_output(
    ['phantomjs', 'phantom_html_to_PDF.js', 'temp.html', out_path, str(x_Size), str(y_Size)])

#remove temporary html file
subprocess.check_output(['rm', 'temp.html])

This calls phantomjs and passes as arguments the path to the javascript from above, the path to the html file, the output file path and the width and height

I hope this is of use for someone