Getting Error 0 when plotting boxplot of a filtered dataset

I am working on Abalone dataset and I am facing a weird problem when plotting a boxplot.

If a run:

plt.figure(figsize=(16,6))
plt.subplot(121)
sns.boxplot(data=df['rings'])

working perfectly!

If I filter the dataset by sex like this:

df_f = df[df['sex']=='F']
df_m = df[df['sex']=='M']
df_i = df[df['sex']=='I']

And i run:

plt.figure(figsize=(16,6))
plt.subplot(121)
sns.boxplot(data=df_m['rings'])

working perfectly!

But if I run the code above for df_f and df_i datasets I get an error:

KeyError: 0

There’s no missing values, all values are int.

What I am missing here?

>Solution :

If you want a box plot per value of a categorical column I suggest:

sns.boxplot(data=df, x='rings', y='sex')