Violin Plot for Data Analysis

Violin Plot is a method to visualize the distribution of numerical data of different variables. It is similar to Box Plot but with a rotated plot on each side, giving more information about the density estimate on the y-axis. The density is mirrored and flipped over and the resulting shape is filled in, creating an image resembling a violin. The advantage of a violin plot is that it can show nuances in the distribution that aren’t perceptible in a boxplot. On the other hand, the boxplot more clearly shows the outliers in the data. Violin Plots hold more information than the box plots, they are less popular. Because of their unpopularity, their meaning can be harder to grasp for many readers not familiar with the violin plot representation. To get the link to Iris Data, click – here. Attribute Information about data set: 

Attribute Information:
   -> sepal length in cm
   -> sepal width in cm
   -> petal length in cm
   -> petal width in cm
   -> class: 
              Iris Setosa
              Iris Versicolour
              Iris Virginica

Number of Instances: 150 

Summary Statistics:
             Min  Max   Mean    SD   Class Correlation
   sepal length: 4.3  7.9   5.84  0.83    0.7826   
    sepal width: 2.0  4.4   3.05  0.43   -0.4194
   petal length: 1.0  6.9   3.76  1.76    0.9490  (high!)
    petal width: 0.1  2.5   1.20  0.76    0.9565  (high!)

Class Distribution: 33.3% for each of 3 classes.

Loading Libraries

Python3

import numpy as np
import pandas as pd
import seaborn as sns
from matplotlib import pyplot
import seaborn

Loading Data

Python3

data = pd.read_csv("Iris.csv")

print (data.head(10))

Output: Description

Python3

data.describe()

Output: Info

Python3

data.info()

Output: Describing ‘SepalLengthCm’ parameter of Iris dataset. 

Python3

data["SepalLengthCm"].describe()

Output: 

count    150.000000
mean       5.843333
std        0.828066
min        4.300000
25%        5.100000
50%        5.800000
75%        6.400000
max        7.900000
Name: SepalLengthCm, dtype: float64

Code #1: Violin Plot for ‘SepalLengthCm’ Parameter. 

Python3

fig, ax = pyplot.subplots(figsize =(9, 7))
sns.violinplot( ax = ax, y = data["SepalLengthCm"] )

Output: As you can see we have a higher density between 5 and 6. That is very significant because as in the SepalLengthCm description, a mean value is at 5.43. Code #2: Violin Plot for ‘SepalLengthWidth’ Parameter. 

Python3

fig, ax = pyplot.subplots(figsize =(9, 7))
sns.violinplot(ax = ax,  y = data["SepalWidthCm"] )

Output: Here also, Higher density is at the mean = 3.05 Code #3: Violin Plot comparing ‘SepalLengthCm’ and ‘SepalWidthCm’. 

Python3

fig, ax = pyplot.subplots(figsize =(9, 7))
sns.violinplot(ax = ax, data = data.iloc[:, 1:3])

Output: Code #4: Violin Plot comparing ‘SepalLengthCm’ species wise. 

Python3

fig, ax = pyplot.subplots(figsize =(9, 7))
sns.violinplot(ax = ax, x = data["Species"],
                  y = data["SepalLengthCm"] )

Output: