(Python Data Visualisation Tutorials)
Scatter plot with linear regression line of best fit
In this data visualisation tutorial, you will learn how to do scatter plot with linear regression using seaborn package in Python.
If you want to understand how two variables change with respect to each other, the line of best fit is the way to go. The below plot shows how the line of best fit differs amongst various groups in the data. To disable the groupings and to just draw one line-of-best-fit for the entire dataset, remove the hue='cyl' parameter from the sns.lmplot() call below.
Setup
Run this once before the plot’s code. The individual charts, however, may redefine its own aesthetics.
# !pip install brewer2mpl
import numpy as np
import pandas as pd
import matplotlib as mpl
import matplotlib.pyplot as plt
import seaborn as sns
import warnings; warnings.filterwarnings(action='once')
large = 22; med = 16; small = 12
params = {'axes.titlesize': large,
'legend.fontsize': med,
'figure.figsize': (16, 10),
'axes.labelsize': med,
'axes.titlesize': med,
'xtick.labelsize': med,
'ytick.labelsize': med,
'figure.titlesize': large}
plt.rcParams.update(params)
plt.style.use('seaborn-whitegrid')
sns.set_style("white")
%matplotlib inline
# Version
print(mpl.__version__)
print(sns.__version__)Scatter plot with linear regression line of best fit
Show Code:
# Import Data
df = pd.read_csv("mpg_ggplot2.csv")
df_select = df.loc[df.cyl.isin([4,8]), :]
# Plot
sns.set_style("white")
gridobj = sns.lmplot(x="displ", y="hwy", hue="cyl", data=df_select,
height=7, aspect=1.6, robust=True, palette='tab10',
scatter_kws=dict(s=60, linewidths=.7, edgecolors='black'))
# Decorations
gridobj.set(xlim=(0.5, 7.5), ylim=(0, 50))
plt.title("Scatterplot with line of best fit grouped by number of cylinders", fontsize=20)
plt.show()
Each regression line in its own column
Alternately, you can show the best fit line for each group in its own column. You cando this by setting the col=groupingcolumn parameter inside the sns.lmplot().
Show Code
# Import Data
df = pd.read_csv("mpg_ggplot2.csv")
df_select = df.loc[df.cyl.isin([4,8]), :]
# Each line in its own column
sns.set_style("white")
gridobj = sns.lmplot(x="displ", y="hwy",
data=df_select,
height=7,
robust=True,
palette='Set1',
col="cyl",
scatter_kws=dict(s=60, linewidths=.7, edgecolors='black'))
# Decorations
gridobj.set(xlim=(0.5, 7.5), ylim=(0, 50))
plt.show()
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