????Express allows you to make many figure types quickly, but not all types you might want are available.
For example, stacked bar charts aren’t currently an easy option.
For those you’ll want to take the other route to the top of the mountain with Cufflinks.
The other pathCufflinksCufflinks is very similar to Express, in that it’s a wrapper for the Plotly API to simplify working with Pandas.
Cufflinks is a third-party open source project that’s been around for over four years.
Install with pip install cufflinks.
Import the module and configure the file for offline use.
import cufflinks as cfcf.
set_config_file(offline=True)Many figure types require only a single line of code with Cufflinks.
For example, stacked bar charts are a breeze.
Example cufflinks stacked bar chartHere’s the code:df = pd.
DataFrame(np.
random.
rand(6, 3), columns=['A', 'B', 'C')df.
iplot(kind='bar', barmode='stack', title='Stacked Bar Chart with Random Data')Note that you’ll use .
iplot() to make your figures with Cufflinks.
Like Express, Cufflinks returns the underlying Plotly figure so you can make more fine-grained modifications.
Unlike Cufflinks, you need to specify asFigure=True in your figure definition to return a figure.
Then you can update the figure just like in Express.
Here’s how that looks if you want to change the title and range of the yaxis.
my_fig = df.
iplot(kind='bar', barmode='stack', title='Stacked Bar Chart with Random Data', asFigure=True)_fig.
layout.
yaxis = dict(title='Members', range=[0, 600])Here are the Cufflinks Docs.
Unfortunately, some things aren’t doable with Cufflinks, such as scattergeo plots.
Comparison of the 3 OptionsHere’s a comparison of code with similar layout for figures created with plotly.
py, Express, and Cufflinks.
plotly.
pyfig = { 'data': [ { 'x': df2007.
gdpPercap, 'y': df2007.
lifeExp, 'text': df2007.
country, 'mode': 'markers', 'name': '2007'}, ], 'layout': { 'title': "Example Scatter Plot with Vanilla plotly.
py" }}py.
iplot(fig)Expresspx.
scatter( df2007, x="gdpPercap", y="lifeExp", title='Example Scatter Plot with Plotly Express')That’s short and sweet!.The default formatting is a bit different and you get the axes titles automatically.
Let’s look at the same chart in Cufflinks.
Cufflinksdf2007.
iplot( kind='scatter', mode='markers', x='gdpPercap', y='lifeExp', title='Example Scatter Plot with Cufflinks')That’s very similar code to Express, but the figure has slightly different defaults.
Both Express and Cufflinks definitely save you keystrokes.
⌨️ This is especially true with many more complicated charts.
????Let’s look at how to return and access the underlying plotly figures.
Updating Cufllinks and Express FiguresLet’s access the layout for the figure created by Cufflinks and add axes titles.
fig = df2007.
iplot( kind='scatter', mode='markers', x='gdpPercap', y='lifeExp', asFigure=True, title='Example Scatter Plot with Cufflinks – Access Underlying Figure')fig.
layout.
xaxis.
title = "GDP per Capita"fig.
layout.
yaxis.
title = "Life Expectancy"fig.
iplot()Here’s how you do the same thing with Express.
Recall that with Express, you don’t need to specify asFigure=True.
fig = px.
scatter( df2007, x="gdpPercap", y="lifeExp", title='Example Scatter Plot with Plotly Express – Access Underlying Figure')fig.
layout.
xaxis.
title = "GDP per Capita"fig.
layout.
yaxis.
title = "Life Expectancy"fig.
iplot()You can access the first data trace to add text labels like this:fig.
data[0].
update( text=df2007['gdpPercap'], textposition=’inside’, textfont=dict(size=10))Choosing among plotly.
py, Express, and CufflinksThe space really is confusing.
At one point not long ago, I thought I was using Express in one part of a project, when I was using Cufflinks!.????♂I’m a big fan of the Zen of Python’s one clear way: “There should be one — and preferably only one — obvious way to do it.
” Two ways leads to research time, choice fatigue, and errors.
Unfortunately there isn’t a single high-level API to make every figure type right now.
However, I definitely would use Cufflinks or Express over vanilla plotly.
py whenever possible.
I suggest you check the Express and Cufflinks docs when you want to build a figure.
Remember that Express requires tidy DataFrames, while Cufflinks is more flexible.
Use whichever of the two libraries fits your needs and has formatting closest to what you want.
Cufflinks is where I look first.
The default formatting between the two libraries can be quite dramatic.
For example, with some random data for X, Y, and Z columns in a DataFrame you can get this with this Cufflinks code:df.
iplot(kind=’scatter’, mode=’markers’, x=’X’, y=’Y’, title=’Random Data’, categories=’Z’)Cool Default Cufflink Scatter Plotor this with this Express code:px.
scatter(df, x=’X’, y=’Y’, color=’Z’, title=’Random Data’)Different Presets with ExpressThat’s quite a difference!Saving FilesOnce you have a figure created, you can mouse-over it and click on the camera icon to export it as a .
png file or click on the Export to plot.
ly link to save the interactive image to Plotly’s servers.
Alternatively, you can download files in interactive HTML format like this:py.
offline.
plot(my_fig, filename=’my_example_file.
html’)If you need more image formats, you can use Plotly’s orca package to download files in formats including .
png, .
jpg, and .
pdf.
You’ll need to install orca first.
The package is not currently available on pypi.
org, so you can’t pip install it.
You can install it via conda or you can install os-specific versions from the orca GitHub page.
Then you don’t need to import the orca library.
Read more about orca here.
Here’s the code to create a .
png file once you have orca installed.
import plotly as plotlyplotly.
io.
write_image(fig, file='my_figure_file.
png', format='png')As you can see, there are a few ways to get your figures out of Plotly.
????Let’s briefly touch on two other components of the Plotly ecosystem so that you know what’s what.
DashWith Plotly Dash you can use Python to make web app dashboards for your team or the world.
There’s a free open source version with nearly 9,000 GitHub stars as of May 1, 2019.
There’s a suite of Dash ad-ons offered by Plotly.
I haven’t used Dash much.
Maybe that will be a focus of a future article.
Follow me to make sure you don’t miss it.
????Chart StudioPlotly Chart Studio makes it easy to create or edit your charts in the browser.
Plotly bills it as “the world’s most sophisticated editor for creating D3.
js and WebGL charts.
No coding required.
” There’s a free version, but annual pricing starts at $99 if you want to save private chart files.
Now that we’ve made it to the top of Mt.
Plotly, let’s take a quick look at other data visualization mountains in the Python range.
Bonus: Other Python Data Viz OptionsThis article isn’t meant to be an exhaustive look at data visualization options, but I’ll mention a few other important options for data scientists to know about, so you have a fairly comprehensive lay of the land.
The old school way to make visualizations in Python is with the vanilla Matplotlib API.
The Pandas Matplotlib API is nice for quick plots.
It creates regular Matplotlib objects.
Seaborn is a great high level wrapper around Matplotlib that lets you quickly make many types of statistical visualizations.
Unfortunately, these options aren’t interactive and are built on a 15-year-old Matplotlib foundation that isn’t super easy to use.
Bokeh is a competitor to Plotly.
It’s open source, interactive, and works with Python.
Holoviews is a higher-level wrapper around Bokeh.
I know folks who like Holoviews.
R folks love Shiny from RStudio.
It lets’ R users create interactive web application visualizations.
Tableau and Microsoft PowerBI are two other popular drag and drop data visualization creation options that integrate with Python.
Tableau is really nice, but requires you to pay money to keep your work private.
I find PowerBI a bit less intuitive, but it’s also very powerful and very popular.
Most all the interactive figure software listed above is using D3.
js under the hood.
It’s super popular.
Wrap and ResourcesIf you’re a data scientist, I encourage you to check out Plotly.
It’s a modern toolbox for making interactive visualizations.
From the top of the mountain, it seems the Plotly juggernaut isn’t likely to be slowed down anytime soon.
Maybe eventually there will be one clear way to make everything you want using Ploly’s high level API options.
For now, I suggest you use Pandas with Cufflinks or with Express whenever you can to save time and make awesome visualizations.
Here are some good Plotly resources:Will Koehrsen has a nice guide to getting started with Cufflinks here.
Here’s a talk by Jon Mease, the plotly.
py lead developer, showing what you can do with plotly.
py v3.
0 in Jupyter Lab.
You can get help in your notebook and make some very cool widgets.
If you haven’t switched to running your Juypter Notebooks in Jupyter Lab yet, this might be the push you need.
????PSA: Whenever you are using color, think about accessibility for folks with color blindness.
It’s easy to use a color-blind-friendly palette.
Here’s one I adopted from ggplot.
Color swatchcolor_list = ["#E69F00", "#56B4E9", "#009E73", "#F0E442", "#D55E00", "#0072B2", "#CC79A7"]I write about data science, Python, and DevOps.
Check out my articles here if you’re into that stuff.
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