Python Forum

Hi out there,

I'd like to delete a line in the dataframe "df_new". Why does it not work? I get the error: "KeyError: '[0] not found in axis".

import pandas as pd
import numpy as np

data = {'x':  [0,1, 2,3,4,5,6,7,8],
        'y': [60, 23, 24,42,56,10,20,25,13],
        'comment': ["false", "true","true","true","true","true","true","true","true"],
        }

df = pd.DataFrame(data)
df_new = df.loc[df['comment']  == "true"]

# This works fine
df = df.drop([0])
# This creates an error: KeyError: '[0] not found in axis'
df_new = df_new.drop([0])

print(type(df))  # <class 'pandas.core.frame.DataFrame'>
print(type(df_new)) # <class 'pandas.core.frame.DataFrame'>

Indexing in pandas is not like indexing a list. Deleting a row does not change the index of the trailing rows. In your example df_new doesn't have an index[0].
You filtered out index[0] when when creating df_new. df_new starts at index[1]

You can reset the index using reset_index()

https://pandas.pydata.org/pandas-docs/st...index.html

import pandas as pd
 
data = {'x':  [0,1, 2,3,4,5,6,7,8],
        'y': [60, 23, 24,42,56,10,20,25,13],
        'comment': ["false", "true","true","true","true","true","true","true","true"],
        }
 
df = pd.DataFrame(data)
df_new = df.loc[df['comment']  == "true"]
print(df_new)
df_new = df_new.reset_index(drop=True)
print(df_new)
df_new = df_new.drop(0)
print(df_new)

Thank you very much!