ValueError: Could not interpret input 'index' when using index with seaborn lineplot

Question

I want the use the index of a pandas DataFrame as x value for a seaborn plot. However, this raises a value error.

A small test example:

import pandas as pd
import seaborn as sns
sns.lineplot(x='index',y='test',hue='test2',data=pd.DataFrame({'test':range(9),'test2':range(9)}))

It raises:

ValueError: Could not interpret input 'index'

Is it not possible to use the index as x values? What am I doing wrong? Python 2.7, seaborn 0.9

Answer 1

You would need to make sure the string you provide to the x argument is actually a column in your dataframe. The easiest solution to achieve that is to reset the index of the dataframe to convert the index to a column.

# reset the index, which results in a column named index
df = pd.DataFrame({'test':range(9),'test2':range(9)}).reset_index()

ax = sns.lineplot(x='index', y='test', data=df)

Initial df

   test  test2
0     0      0
1     1      1
2     2      2
3     3      3
4     4      4
5     5      5
6     6      6
7     7      7
8     8      8

df after reset_index

   index  test  test2
0      0     0      0
1      1     1      1
2      2     2      2
3      3     3      3
4      4     4      4
5      5     5      5
6      6     6      6
7      7     7      7
8      8     8      8

Answer 2

I know it's an old question, and maybe this wasn't around back then, but there's a much simpler way to achieve this:

If you just pass a series from a dataframe as the 'data' parameter, seaborn will automatically use the index as the x values.

sns.lineplot(data=df.column1)

Answer 3

I would rather prefer to use it this way. You need to remove hue as I assume it has a different purpose which doesn't apply in your current DataFrame because you have a single line. Visit the official docs here for more info.

df=pd.DataFrame({'test':range(9),'test2':range(9)})
sns.lineplot(x=df.index, y='test', data=df)

Output