Iterate over the rows of a DataFrame as (index, Series) pairs.
it : generator
A generator that iterates over the rows of the frame.
Because iterrows returns a Series for each row, it does not preserve dtypes across the rows (dtypes are preserved across columns for DataFrames). For example,
>>> df = pd.DataFrame([[1, 1.5]], columns=['int', 'float']) >>> row = next(df.iterrows()) >>> row int 1.0 float 1.5 Name: 0, dtype: float64 >>> print(row['int'].dtype) float64 >>> print(df['int'].dtype) int64
To preserve dtypes while iterating over the rows, it is better to use itertuples() which returns tuples of the values and which is generally faster as iterrows.
You should never modify something you are iterating over. This is not guaranteed to work in all cases. Depending on the data types, the iterator returns a copy and not a view, and writing to it will have no effect.