The visualization artifact Plotly plays with the violin chart

Visual artifact Plotly to play the violin chart

In the previous Plotly article, I have introduced how to use Plotly to make common visualization graphics such as histograms, scatter charts, pie charts, as well as K-line charts and box charts. This article introduces how to use Plotly to draw violin diagrams, also A statistical graph, based on two methods:

• Based on plotly_express
• Based on plotly.graph_objects

Violin illustration

Take a look at the actual effect of the violin chart drawn:

So what exactly is a violin chart?

Violin Plot is a graph used to display data distribution and probability density.

A website for learning visual graphics: datavizcatalogue.com/.

It combines the dual features of the box plot and density plot described earlier, and can be used to display the distribution shape of the data.

• The thick black bar in the middle: indicates the range of quartiles
• White point in the middle: indicates the median
• Extended thin black line: represents the 95% confidence interval

Plotly series

Plotly's articles will form a serial series. The first 10 Plotly visualization articles are:

• Cool! 36 pictures Fall in love with the advanced visualization artifact Plotly_Express
• Plotly play with scatter plots
• Plotly play with pie charts
• Plotly play funnel chart
• Plotly play with histogram
• Plotly play with bubble chart
• Plotly play with stock chart
• Plotly play with Gantt chart
• Plotly play with box plots
• Plotly play area chart

Import library, data

First import the required libraries:

Import numpy AS NP
 Import PANDAS AS pd
 Import plotly_express AS PX
 Import plotly.graph_objects AS Go
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The consumption data that comes with pandas used in this article:

# Uses consumption data tips
tips = px.data.tips()
tips.head()
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Point-based violin chart

The first thing I draw is a violin chart based on data points:

fig = px.strip(
    tips,    # Specified data 
    x = 'day' ,    # xy axis 
    y = 'total_bill' ,
    color = 'day'   # color
    )

fig.show()
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Draw the violin chart according to the values of the 4 days:

Implementation based on Plotly_Express

Basic violin diagram

fig = px.violin(tips,y= "total_bill" )   # Use total_bill data
fig.show()
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Change a copy of the data and then plot:

fig = px.violin(tips,y= "tip" )   # Use tip
fig.show()
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Violin chart with data points

The above graph has no data points. The following is to display the data points next to the violin chart. The parameter is points:

fig = px.violin(
    tips,
    y= "total_bill" ,
    box= True ,    # Draw a box diagram in the violin chart after opening it 
    points= 'all'   # all-all outliers-outliers False-do not display, default
)

fig.show()
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There are no outliers in this case, so points=outliers or False, the result is the same:

Grouped violin chart

Draw different violin diagrams through different values of the fields:

fig = px.violin(
    tips,
    y= "total_bill" ,   # plotted data 
    x= "day" ,
    color= "sex" ,
    box = True ,
    points= "all" ,
    hover_data=tips.columns   # Data information displayed on hover
)

fig.show()
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Covering type, group type violin chart

The two different graphics are mainly determined by the mode of the violin, the parameter used is violinmode:

fig = px.violin(
    tips,
    y = 'total_bill' ,
    color = 'sex' ,
    violinmode = 'overlay' ,    # overlay-overlay group-group
    hover_data=tips.columns
)

fig.show()
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fig = px.violin(
    tips,
    y = 'total_bill' ,
    color = 'sex' ,
    violinmode = 'group' ,    # overlay-overlay group -group
    hover_data=tips.columns
)

fig.show()
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Based on go.Violin

Basic violin diagram

  fig = go.Figure(data=go.Violin(
    y=tips[ 'total_bill' ],   # drawing data 
    box_visible= True ,   # whether the inner box is displayed 
    line_color = 'red' ,   # line color 
    meanline_visible = True ,   # whether to display the midline 
    fillcolor = 'seagreen' ,   # fill color 
    opacity= 0.5 ,   # Transparency 
    x0 = 'Tip-violin graph'    # x-axis title
))

fig.update_layout(yaxis_zeroline = False )

fig.show()
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Multiple violin illustration

Draw multiple violins in one canvas at the same time. The day field in consumer data tips has 4 different values:

Through a for loop to traverse to achieve the drawing of 4 graphics:

fig1 = go.Figure()   # Generate a Figure object

# Add 4 traces trace 
for day in day_list on the object by looping :
    fig1.add_trace(go.Violin(
        x=tips[ "day" ][tips[ "day" ] == day],
        y=tips[ "total_bill" ][tips[ "day" ] == day],
        name=day,
        box_visible = True ,
        meanline_visible = True
       ))
    
fig1.show()
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Grouped violin chart

python

fig2 = go.Figure()

fig2.add_trace(go.Violin(
    x=tips[ tips[ 'sex' ] == 'Male' ][ 'day' ],   # xy axis data of the drawing 
    y=tips[ 'total_bill' ][ tips[ 'sex' ] == 'Male' ],
 # legendgroup=' ', # Legend grouping 
# scalegroup=' ',   
    name= ' ' ,   # graph track name 
    line_color = 'blue'   # line color
))

fig2.add_trace(go.Violin(
    x=tips[ 'day' ][tips[ 'sex' ] == 'Female' ],
    y=tips[ 'total_bill' ][tips[ 'sex' ] == 'Female' ],
 # legendgroup=' ', 
# scalegroup=' ', 
    name= ' ' ,
    line_color = 'orange' )
)

# Set whether the box and the median line show 
fig2.update_traces(box_visible = True , meanline_visible = True )
  
# Violin graph mode: overlay overlay type group group 
fig2.update_layout(violinmode = 'group' )  

fig2.show()
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Positive and negative violin diagram

In the violin picture, we can see that it is composed of two parts, which are divided into negative and positive. Different values will present different graphics:

import plotly.graph_objects as go

import pandas as pd

# How to use pandas to read the online csv file 
df = pd.read_csv( "https://raw.githubusercontent.com/plotly/datasets/master/violin_data.csv" )

fig = go.Figure()

fig.add_trace(go.Violin(
    x=df[ 'day' ][ df[ 'smoker' ] == 'Yes' ],
    y=df[ 'total_bill' ][ df[ 'smoker' ] == 'Yes' ],
 # legendgroup='Yes', 
# scalegroup='Yes', 
    name= 'Yes' ,
    side = 'negative' ,   #'both-all','positive-right','negative-left' 
    line_color = 'blue' )
)

fig.add_trace(go.Violin(
    x=df[ 'day' ][ df[ 'smoker' ] == 'No' ],
    y=df[ 'total_bill' ][ df[ 'smoker' ] == 'No' ],
 # legendgroup='No', 
# scalegroup='No', 
    name= 'No' ,
    side = 'positive' ,
    line_color = 'lightseagreen' )
)

# Set the trajectory parameter 
fig.update_traces(meanline_visible= True ,   # Whether the median shows 
                  points= 'all' ,   # Whether to display points 
                  jitter= 0.05 ,   # Add jitter between each point, the visualization effect is better 
                  scalemode= ' count' )    #'width','count'

fig.update_layout(violingap = 0 , violinmode = 'overlay' )   # Set interval and mode

fig.show()
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Senior Violin Illustration

Introduce two examples of advanced violin diagrams on the official website:

import plotly.graph_objects as go

import pandas as pd

df = pd.read_csv( "https://raw.githubusercontent.com/plotly/datasets/master/violin_data.csv" )

# Set the position of the point and the display of the legend 
pointpos_male = [- 0.9 ,- 1.1 ,- 0.6 ,- 0.3 ]
pointpos_female = [ 0.45 , 0.55 , 1 , 0.4 ]
show_legend = [ True , False , False , False ]  

fig = go.Figure()

# pd.unique(df['day']): Represents the unique number of days 
for i in  range ( 0 , len (pd.unique(df[ 'day' ]))):
    fig.add_trace(go.Violin(
        # Add two axis data 
        x=df[ 'day' ][(df[ 'sex' ] == 'Male' ) & (df[ 'day' ] == pd.unique(df[ 'day' ]) [i])],
        y=df[ 'total_bill' ][(df[ 'sex' ] == 'Male' )&(df[ 'day' ] == pd.unique(df[ 'day' ])[i])],
         # Set legend and scale group, name 
        legendgroup = 'M' ,
        scalegroup = 'M' ,
        name= 'M' ,
         # Set the displayed data: negative left positive right 
        side = 'negative' ,
        pointpos=pointpos_male[i], # 
        line_color = 'lightseagreen' ,
        showlegend=show_legend[i])
             )
    fig.add_trace(go.Violin(
        x=df[ 'day' ][(df[ 'sex' ] == 'Female' ) &(df[ 'day' ] == pd.unique(df[ 'day' ])[i])],
        y=df[ 'total_bill' ][(df[ 'sex' ] == 'Female' )&(df[ 'day' ] == pd.unique(df[ 'day' ])[i])],
        legendgroup = 'F' ,
        scalegroup = 'F' ,
        name = 'F' ,
        side = 'positive' ,
        pointpos=pointpos_female[i],
        line_color = 'mediumpurple' ,
        showlegend=show_legend[i])
)

# Set the trajectory parameter 
fig.update_traces(meanline_visible= True ,   # Whether the median shows 
                  points= 'all' ,   # Whether to display points 
                  jitter= 0.05 ,   # Add jitter between each point, the visualization effect is better 
                  scalemode= ' count' )    #'width','count'
fig.update_layout(
    title_text= "Advanced Violin Drawing" ,
    violingap = 0 ,   # The interval between the violin graphs 
    violingroupgap = 0 ,   # The interval between the violin graph groups 
    violinmode = 'overlay'   # Overlay mode
)

fig.show()
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The other is an example of drawing Ridgeline (ridge type) Plots graphs, as an appreciation:

import plotly.graph_objects as go
 from plotly.colors import n_colors
 import numpy as np
np.random.seed( 1 )

data = (np.linspace( 1 , 2 , 12 )[:, np.newaxis] * np.random.randn( 12 , 200 ) +
            (np.arange( 12 ) + 2 * np.random.random( 12 ))[:, np.newaxis])

print (data)
 #'rgb(5, 200, 200)','rgb(200, 10, 10)' represents the first and last color, 12 represents the number, colortype represents the type 
colors = n_colors( 'rgb( 5, 200, 200)' , 'rgb(200, 10, 10)' , 12 , colortype = 'rgb' )
 print (colors)


fig = go.Figure()
for data_line, color in  zip (data, colors):
    fig.add_trace(go.Violin(x=data_line, line_color=color))

fig.update_traces(orientation = 'h' , side = 'positive' , width = 3 , points = False )

fig.update_layout(xaxis_showgrid = False , xaxis_zeroline = False )

fig.show()
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