unsupported operand type(s) for -: 'str' and 'float'

[qq_36728692]

plt.figure(figsize = (8, 8))

# Graph the age bins and the average of the target as a bar plot
plt.bar(age_groups.index.astype(str), 100 * age_groups['TARGET']) （需要改的代码行）

# Plot labeling
plt.xticks(rotation = 75); plt.xlabel('Age Group (years)'); plt.ylabel('Failure to Repay (%)')
plt.title('Failure to Repay by Age Group');

系统报错是：unsupported operand type(s) for -: 'str' and 'float'

而我想的到的效果是：


不知道该如何更正TAT