In relation with this Group by Certain Age Group in Pandas
I am trying to group them in a single boxplot like this. 
But I encountered an issue while using this code.
cn = ['AgeUnder18', 'Age19to25', 'Age26to29'] sns.boxplot(x=cn, y='AveMonthSpend', data=df) Error:
The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
You need to convert the dataframe to "long form":
import matplotlib.pyplot as plt import seaborn as sns import pandas as pd import numpy as np cn = ['AgeUnder18', 'Age19to25', 'Age26to29'] df = pd.DataFrame({age_group: np.random.uniform(45, 65, 7) for age_group in cn}) df_melted = df.melt(value_vars=cn, value_name='AveMonthSpend', var_name='Age Bin') sns.boxplot(y='Age Bin', x='AveMonthSpend', data=df_melted, palette='Greys') plt.tight_layout() plt.show() 
This supposes the original dataframe looks like:
Out[10]: AgeUnder18 Age19to25 Age26to29 0 64.980248 64.673755 56.489776 1 59.858895 48.921889 62.877826 2 62.357871 51.599347 55.651448 3 47.206124 45.817266 52.893839 4 57.627501 51.820863 59.616511 5 61.999523 63.443241 45.919390 6 56.616062 48.353018 46.282314 