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I have always made new columns in pandas using the following:
df['new_column'] = value
I am using this method, however, am receiving the warning for setting a copy.
What is the way to make a new column without creating a copy?
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Create a new column by assigning the output to the DataFrame with a new column name in between the [] . Operations are element-wise, no need to loop over rows. Use rename with a dictionary or function to rename row labels or column names.
To insert a single column: Right-click the whole column to the right of where you want to add the new column, and then select Insert Columns. To insert multiple columns: Select the same number of columns to the right of where you want to add new ones. Right-click the selection, and then select Insert Columns.
Use an empty string to create an empty column in a Pandas dataframe. Use the syntax DataFrame[new_column] = "" to create an empty column named new_column in the Dataframe .
Using apply() method If you need to apply a method over an existing column in order to compute some values that will eventually be added as a new column in the existing DataFrame, then pandas. DataFrame. apply() method should do the trick.
Try using
df.loc[:,'new column'] = value
As piRSquared comments, dfis probably a copy of another DataFrame and when you set values to df it probably incurs in what is called chain indexing. Refer to pandas docs for further information.
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