Plotly is a charting module for Python. It can create publication-quality charts. It supports many types of charts/plots including line charts, bar charts, bubble charts and many more.

The library is free and open source. In this tutorial you’ll learn how to create a line chart with plot.ly. It can be seen as more expansive alternative to matplotlib.

Related course: Matplotlib Examples and Video Course

Example

introduction

Install plotly from the PyPi repository. In a new virtual environment install plotly, you can use the program pip for that.

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pip install plotly

Plotly provides a webservice for plotting charts. Graphs are saved inside your online Plotly account. This is optional, Plotly can be used offline.

Offline plotting has two options:

  • Use plotly.offline.plot() to create and standalone HTML. This file can be opened in your browser

  • Use plotly.offline.iplot() when working offline in a Jupyter Notebook.

online plot

Online plots require an acount on plot.ly

Change to your username and API key

Open the file ~/.plotly/.credentials and update your API key.

Then create this program:

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import plotly.plotly as py
import plotly.graph_objs as go
import numpy as np

py.sign_in(username='voorbeeld', api_key='L0McCrDpID71OLCEgRtK')

mx = [1, 2, 3, 4]
my = [1, 2, 3, 4]

trace = go.Scatter(
    x = mx,
        y = my
	)

data = [trace]
py.plot(data)

Run the program from the terminal. Then open the url https://plot.ly/organize/home/#/ where your chart will show up.

plotly plot with python

standalone HTML (plotly.offline.plot)

The code below creates a new HTML file. This HTML file when opened with a browser (Firefox, Chrome) will show the chart.

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import plotly
import plotly.graph_objs as go

plotly.offline.plot({
    "data": [go.Scatter(x=[1, 2, 3, 4], y=[1, 2, 3, 4])],
        "layout": go.Layout(title="line chart")
	}, auto_open=True)

iPython jupyter notebook

An alternative method is to use jupyter notebook (ipython). ipython is a powerful interactive shell.

You can install it with the command

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python3 -m pip install jupyter
jupyter notebook

This will start a web server.
Click new -> notebook -> python3 from the /tree page.

In the code box paste the code below:

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import plotly
import plotly.graph_objs as go

plotly.offline.init_notebook_mode(connected=True)

plotly.offline.iplot({
    "data": [go.Scatter(x=[1, 2, 3, 4], y=[4, 3, 2, 1])],
        "layout": go.Layout(title="hello world")
	})

Then click on run, the chart will show below the code.

If you are new to matplotlib, then I highly recommend this course.