CODEWITHSUNDEEP
pythonpandas
user7468395
user7468395

Reputation: 1349

How to avoid SettingWithCopyWarning when setting a single value?

How can I avoid the warning SettingWithCopyWarning in this case?

Normally, it is enough to use a copy() of a previously created DataFrame. This does not make sense in this situation:

import pandas as pd
import numpy as np
df = pd.DataFrame({"a": [7, 2, 3], "b": [4, 5, 6], "c": [np.nan, np.nan, np.NaN]})
df.c.iloc[0] = 100

.

SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame
See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  self._setitem_with_indexer(indexer, value)

Upvotes: 2

Views: 2337

Answers (1)

jezrael
jezrael

Reputation: 862841

Solution if default RangeIndex is use DataFrame.loc with specify index and column value:

df.loc[0, 'c'] = 100
print (df)
   a  b      c
0  7  4  100.0
1  2  5    NaN
2  3  6    NaN

If want set by positions with DataFrame.iloc is necessry Index.get_loc for position of column c:

df.iloc[0, df.columns.get_loc('c')] = 100

Upvotes: 3

Related Questions