Change the starting point of graphs (The Y-axis)

Question

Dataset:

I have the above dataset. I need to plot a graph where the starting point of y-axis needs to be 0, irrespective of the values in the dataset. The x-axis is the index(Time) and y-axis is Jolt 1, Jolt 2,...

I have a graph showing 2 different plots (the blue curve starts at y=0). I want the orange plot to start from 0 too to compare the trends visually.

Graph:

Here is the code

import pandas as pd
import matplotlib.pyplot as plt

df.set_index('Time').plot()
plt.legend(loc='center left', bbox_to_anchor=(1.0, 0.5))

How do I modify the code to get the desired output?

Answer 1

You can set the 'Time' column as the index of your dataframe:

df = df.set_index('Time')

then you can loop over the remaining columns and plot them with respect to the dataframe index. In order to make all lines start from 0, you have to subtract to each column the respective starting point at the index 0:

for column in df.columns:
    ax.plot(df.index, df[column] - df.loc[0, column], label = column)

Complete Code

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt


df = pd.DataFrame()
df['Time'] = np.arange(0, 0.6, 0.1)
df['Jolt 1'] = np.random.rand(len(df['Time']))
df['Jolt 2'] = np.random.rand(len(df['Time'])) + np.random.randint(low = -5, high = 5)
df['Jolt 3'] = np.random.rand(len(df['Time'])) + np.random.randint(low = -5, high = 5)
df = df.set_index('Time')


fig, ax = plt.subplots()

for column in df.columns:
    ax.plot(df.index, df[column] - df.loc[0, column], label = column)

ax.legend(frameon = True)

plt.show()

Plot