Python Graph snippets

09 Apr 2019

Plotly Express snippets, for quick plots in Python.

The objective of this post is to provide quick notes and how to for common graphs. For more inspiration check out the actual Plotly Express website.

For starters

import pandas as pd
import plotly.express as px

layout = {
    'showlegend': False,
    'margin': {'b':10, 'l':20, 'r':50, 't':50},
    'font': {'size': 19},
    'xaxis': {'zerolinewidth': 2, 'zerolinecolor':'black'},
    'yaxis': {'zerolinewidth': 2, 'zerolinecolor':'black'},
    'template': 'plotly_white',
}
px.defaults.color_discrete_sequence = px.colors.qualitative.T10

# Convenient function to display dataframe
def display_n(df,n):
    with pd.option_context('display.max_rows',n*2):
        display(df)

Here is a convinient list of Plotly’s default colors :

'#1f77b4', rgba(55, 128, 191, 1.0) // muted blue
'#ff7f0e', rgba(255, 127, 14, 1.0) // safety orange
'#2ca02c', rgba(44, 160, 44, 1.0) // cooked asparagus green
'#d62728', rgba(214, 39, 40, 1.0) // brick red
'#9467bd', rgba(148, 103, 189, 1.0) // muted purple
'#8c564b', rgba(140, 86, 75, 1.0) // chestnut brown
'#e377c2', rgba(227, 119, 194, 1.0) // raspberry yogurt pink
'#7f7f7f', rgba(127, 127, 127, 1.0) // middle gray
'#bcbd22', rgba(188, 189, 34, 1.0) // curry yellow-green
'#17becf' rgba(23, 190, 207, 1.0)  // blue-teal

More on discrete color sequences here, or continuous ones here

Bar graph

fig = px.bar(graph)
fig = px.bar(graph, x='index', y='self_suff_%', color='algo',
             barmode='group', opacity=0.8)

# Change bar color, and surrounding line
fig.data[0].update(
   {'marker': {'color': 'rgba(55, 128, 191, 0.7)',
               'line': {'width': 1.5,
               'color': 'rgba(55, 128, 191, 1.0)'}}})
# Red dashed line
fig.add_shape(
 type='line',
 x0="x0", x1="x1", y0=threshold, y1=threshold,
 line={'dash': 'dash', 'width': 5,
       'color': 'rgba(214, 39, 40, 0.7)'})

fig.update_layout(
   layout,
   showlegend=False,
   xaxis_title="",
   yaxis_title="My Title [Unit]")
fig.show()
fig.write_image("fig.svg")

Line graph

fig = px.line(graph)

# One line is filled
fig.update_traces(line_width=3)
fig.data[1].update(fill="tozeroy", line_width=3,
                   fillcolor="rgba(255, 127, 14, 0.1)")

fig.update_layout(
    layout,
    height=400,
    width=800,
    showlegend=False,
    xaxis_title="",
    yaxis_title="Power [kW]",
    yaxis_showline=True, yaxis_linewidth=2, yaxis_linecolor='black',
    xaxis_showline=False, xaxis_linewidth=2, xaxis_linecolor='black',
    rangeslider_visible=False)
fig.show()
fig.write_image("fig.svg")