Alfonso Alfonso - 1 month ago 6
Python Question

Plot bar graph from Pandas DataFrame

Assuming i have a

DataFrame
that looks like this:

Hour | V1 | V2 | A1 | A2
0 | 15 | 13 | 25 | 37
1 | 26 | 52 | 21 | 45
2 | 18 | 45 | 45 | 25
3 | 65 | 38 | 98 | 14


Im trying to create a bar plot to compare columns
V1
and
V2
by the
Hour
.
When I do:

import matplotlib.pyplot as plt
ax = df.plot(kind='bar', title ="V comp",figsize=(15,10),legend=True, fontsize=12)
ax.set_xlabel("Hour",fontsize=12)
ax.set_ylabel("V",fontsize=12)


I get a plot and a legend with all the columns' values and names. How can I modify my code so the plot and legend only displays the columns
V1
and
V2

Answer

To plot just a selection of your columns you can select the columns of interest by passing a list to the subscript operator:

ax = df[['V1','V2']].plot(kind='bar', title ="V comp", figsize=(15, 10), legend=True, fontsize=12)

What you tried was df['V1','V2'] this will raise a KeyError as correctly no column exists with that label, although it looks funny at first you have to consider that your are passing a list hence the double square brackets [[]].

import matplotlib.pyplot as plt
ax = df[['V1','V2']].plot(kind='bar', title ="V comp", figsize=(15, 10), legend=True, fontsize=12)
ax.set_xlabel("Hour", fontsize=12)
ax.set_ylabel("V", fontsize=12)
plt.show()

enter image description here