dask.dataframe.to_numeric

dask.dataframe.to_numeric(arg, errors='raise', meta=None)[source]

Convert argument to a numeric type.

This docstring was copied from pandas.to_numeric.

Some inconsistencies with the Dask version may exist.

Return type depends on input. Delayed if scalar, otherwise same as input. For errors, only “raise” and “coerce” are allowed.

The default return dtype is float64 or int64 depending on the data supplied. Use the downcast parameter to obtain other dtypes.

Please note that precision loss may occur if really large numbers are passed in. Due to the internal limitations of ndarray, if numbers smaller than -9223372036854775808 (np.iinfo(np.int64).min) or larger than 18446744073709551615 (np.iinfo(np.uint64).max) are passed in, it is very likely they will be converted to float so that they can stored in an ndarray. These warnings apply similarly to Series since it internally leverages ndarray.

Parameters
argscalar, list, tuple, 1-d array, or Series

Argument to be converted.

errors{‘ignore’, ‘raise’, ‘coerce’}, default ‘raise’
  • If ‘raise’, then invalid parsing will raise an exception.

  • If ‘coerce’, then invalid parsing will be set as NaN.

  • If ‘ignore’, then invalid parsing will return the input.

downcast{‘integer’, ‘signed’, ‘unsigned’, ‘float’}, default None (Not supported in Dask) (Not supported in Dask)

If not None, and if the data has been successfully cast to a numerical dtype (or if the data was numeric to begin with), downcast that resulting data to the smallest numerical dtype possible according to the following rules:

  • ‘integer’ or ‘signed’: smallest signed int dtype (min.: np.int8)

  • ‘unsigned’: smallest unsigned int dtype (min.: np.uint8)

  • ‘float’: smallest float dtype (min.: np.float32)

As this behaviour is separate from the core conversion to numeric values, any errors raised during the downcasting will be surfaced regardless of the value of the ‘errors’ input.

In addition, downcasting will only occur if the size of the resulting data’s dtype is strictly larger than the dtype it is to be cast to, so if none of the dtypes checked satisfy that specification, no downcasting will be performed on the data.

Returns
ret

Numeric if parsing succeeded. Return type depends on input. Series if Series, otherwise ndarray.

See also

DataFrame.astype

Cast argument to a specified dtype.

to_datetime

Convert argument to datetime.

to_timedelta

Convert argument to timedelta.

numpy.ndarray.astype

Cast a numpy array to a specified type.

DataFrame.convert_dtypes

Convert dtypes.

Examples

Take separate series and convert to numeric, coercing when told to

>>> s = pd.Series(['1.0', '2', -3])  
>>> pd.to_numeric(s)  
0    1.0
1    2.0
2   -3.0
dtype: float64
>>> pd.to_numeric(s, downcast='float')  
0    1.0
1    2.0
2   -3.0
dtype: float32
>>> pd.to_numeric(s, downcast='signed')  
0    1
1    2
2   -3
dtype: int8
>>> s = pd.Series(['apple', '1.0', '2', -3])  
>>> pd.to_numeric(s, errors='ignore')  
0    apple
1      1.0
2        2
3       -3
dtype: object
>>> pd.to_numeric(s, errors='coerce')  
0    NaN
1    1.0
2    2.0
3   -3.0
dtype: float64

Downcasting of nullable integer and floating dtypes is supported:

>>> s = pd.Series([1, 2, 3], dtype="Int64")  
>>> pd.to_numeric(s, downcast="integer")  
0    1
1    2
2    3
dtype: Int8
>>> s = pd.Series([1.0, 2.1, 3.0], dtype="Float64")  
>>> pd.to_numeric(s, downcast="float")  
0    1.0
1    2.1
2    3.0
dtype: Float32