snowflake.ml.modeling.preprocessing.OrdinalEncoder

class snowflake.ml.modeling.preprocessing.OrdinalEncoder(*, categories: Union[str, List[Union[ndarray[Any, dtype[int64]], ndarray[Any, dtype[float64]], ndarray[Any, dtype[str_]], ndarray[Any, dtype[bool_]]]], Dict[str, Union[ndarray[Any, dtype[int64]], ndarray[Any, dtype[float64]], ndarray[Any, dtype[str_]], ndarray[Any, dtype[bool_]]]]] = 'auto', handle_unknown: str = 'error', unknown_value: Optional[Union[int, float]] = None, encoded_missing_value: Union[int, float] = nan, input_cols: Optional[Union[str, Iterable[str]]] = None, output_cols: Optional[Union[str, Iterable[str]]] = None, passthrough_cols: Optional[Union[str, Iterable[str]]] = None, drop_input_cols: Optional[bool] = False)

Bases: BaseTransformer

Encodes categorical features as an integer array.

In other words, each category (i.e., distinct numeric or string value) is assigned an integer value, starting with zero.

For more details on what this transformer does, see sklearn.preprocessing.OrdinalEncoder.

Parameters:
  • categories – Union[str, List[type_utils.LiteralNDArrayType], Dict[str, type_utils.LiteralNDArrayType]],

  • default="auto" – The string ‘auto’ (the default) causes the categories to be extracted from the input columns. To specify the categories yourself, pass either (1) a list of ndarrays containing the categories or (2) a dictionary mapping the column name to an ndarray containing the categories.

  • handle_unknown

    str, default=”error” Specifies how unknown categories are handled during transformation. Applicable only if categories is not ‘auto’. Valid values are:

    • ’error’: Raise an error if an unknown category is present during transform (default).

    • ’use_encoded_value’: When an unknown category is encountered during transform, the specified

      encoded_missing_value (below) is used.

  • unknown_value – Optional[Union[int, float]], default=None When the parameter handle_unknown is set to ‘use_encoded_value’, this parameter is required and will set the encoded value of unknown categories. It has to be distinct from the values used to encode any of the categories in fit.

  • encoded_missing_value – Union[int, float], default=np.nan The value to be used to encode unknown categories.

  • input_cols – Optional[Union[str, List[str]]], default=None The name(s) of one or more columns in the input DataFrame containing feature(s) to be encoded. Input columns must be specified before fit with this argument or after initialization with the set_input_cols method. This argument is optional for API consistency.

  • output_cols – Optional[Union[str, List[str]]], default=None The prefix to be used for encoded output for each input column. The number of output column prefixes specified must equal the number of input columns. Output column prefixes must be specified before transform with this argument or after initialization with the set_output_cols method.

  • passthrough_cols – Optional[Union[str, List[str]]], default=None A string or a list of strings indicating column names to be excluded from any operations (such as train, transform, or inference). These specified column(s) will remain untouched throughout the process. This option is helpful in scenarios requiring automatic input_cols inference, but need to avoid using specific columns, like index columns, during training or inference.

  • drop_input_cols – Optional[bool], default=False Remove input columns from output if set True. False by default.

categories_

List[type_utils.LiteralNDArrayType] The categories of each feature determined during fitting. Maps input column names to an array of the detected categories. Attributes are valid only after fit() has been called.

Type:

dict of ndarray

Encode categorical features as an integer column.

The input to this transformer should be an array-like of integers or strings, denoting the values taken on by categorical (discrete) features. The features are converted to ordinal integers. This results in a single column of integers (0 to n_categories - 1) per feature.

Parameters:
  • categories

    ‘auto’, list of array-like, or dict {column_name: ndarray([category])}, default=’auto’ Categories (unique values) per feature: - ‘auto’: Determine categories automatically from the training data. - list: categories[i] holds the categories expected in the ith

    column. The passed categories should not mix strings and numeric values within a single feature, and should be sorted in case of numeric values.

    • dict: categories[column_name] holds the categories expected in the column provided. The passed categories should not mix strings and numeric values within a single feature, and should be sorted in case of numeric values.

    The used categories can be found in the categories_ attribute.

  • handle_unknown – {‘error’, ‘use_encoded_value’}, default=’error’ When set to ‘error’ an error will be raised in case an unknown categorical feature is present during transform. When set to ‘use_encoded_value’, the encoded value of unknown categories will be set to the value given for the parameter unknown_value.

  • unknown_value – int or np.nan, default=None When the parameter handle_unknown is set to ‘use_encoded_value’, this parameter is required and will set the encoded value of unknown categories. It has to be distinct from the values used to encode any of the categories in fit.

  • encoded_missing_value – Encoded value of missing categories.

  • input_cols – Single or multiple input columns.

  • output_cols – Single or multiple output columns.

  • passthrough_cols – A string or a list of strings indicating column names to be excluded from any operations (such as train, transform, or inference). These specified column(s) will remain untouched throughout the process. This option is helful in scenarios requiring automatic input_cols inference, but need to avoid using specific columns, like index columns, during in training or inference.

  • drop_input_cols – Remove input columns from output if set True. False by default.

categories_

The categories of each feature determined during fitting.

Methods

fit(dataset: Union[DataFrame, DataFrame]) BaseEstimator

Runs universal logics for all fit implementations.

get_input_cols() List[str]

Input columns getter.

Returns:

Input columns.

get_label_cols() List[str]

Label column getter.

Returns:

Label column(s).

get_output_cols() List[str]

Output columns getter.

Returns:

Output columns.

get_params(deep: bool = True) Dict[str, Any]

Get parameters for this transformer.

Parameters:

deep – If True, will return the parameters for this transformer and contained subobjects that are transformers.

Returns:

Parameter names mapped to their values.

get_passthrough_cols() List[str]

Passthrough columns getter.

Returns:

Passthrough column(s).

get_sample_weight_col() Optional[str]

Sample weight column getter.

Returns:

Sample weight column.

get_sklearn_args(default_sklearn_obj: Optional[object] = None, sklearn_initial_keywords: Optional[Union[str, Iterable[str]]] = None, sklearn_unused_keywords: Optional[Union[str, Iterable[str]]] = None, snowml_only_keywords: Optional[Union[str, Iterable[str]]] = None, sklearn_added_keyword_to_version_dict: Optional[Dict[str, str]] = None, sklearn_added_kwarg_value_to_version_dict: Optional[Dict[str, Dict[str, str]]] = None, sklearn_deprecated_keyword_to_version_dict: Optional[Dict[str, str]] = None, sklearn_removed_keyword_to_version_dict: Optional[Dict[str, str]] = None) Dict[str, Any]

Get sklearn keyword arguments.

This method enables modifying object parameters for special cases.

Parameters:
  • default_sklearn_obj – Sklearn object used to get default parameter values. Necessary when sklearn_added_keyword_to_version_dict is provided.

  • sklearn_initial_keywords – Initial keywords in sklearn.

  • sklearn_unused_keywords – Sklearn keywords that are unused in snowml.

  • snowml_only_keywords – snowml only keywords not present in sklearn.

  • sklearn_added_keyword_to_version_dict – Added keywords mapped to the sklearn versions in which they were added.

  • sklearn_added_kwarg_value_to_version_dict – Added keyword argument values mapped to the sklearn versions in which they were added.

  • sklearn_deprecated_keyword_to_version_dict – Deprecated keywords mapped to the sklearn versions in which they were deprecated.

  • sklearn_removed_keyword_to_version_dict – Removed keywords mapped to the sklearn versions in which they were removed.

Returns:

Sklearn parameter names mapped to their values.

set_drop_input_cols(drop_input_cols: Optional[bool] = False) None
set_input_cols(input_cols: Optional[Union[str, Iterable[str]]]) Base

Input columns setter.

Parameters:

input_cols – A single input column or multiple input columns.

Returns:

self

set_label_cols(label_cols: Optional[Union[str, Iterable[str]]]) Base

Label column setter.

Parameters:

label_cols – A single label column or multiple label columns if multi task learning.

Returns:

self

set_output_cols(output_cols: Optional[Union[str, Iterable[str]]]) Base

Output columns setter.

Parameters:

output_cols – A single output column or multiple output columns.

Returns:

self

set_params(**params: Dict[str, Any]) None

Set the parameters of this transformer.

The method works on simple transformers as well as on nested objects. The latter have parameters of the form <component>__<parameter> so that it’s possible to update each component of a nested object.

Parameters:

**params – Transformer parameter names mapped to their values.

Raises:

SnowflakeMLException – Invalid parameter keys.

set_passthrough_cols(passthrough_cols: Optional[Union[str, Iterable[str]]]) Base

Passthrough columns setter.

Parameters:

passthrough_cols – Column(s) that should not be used or modified by the estimator/transformer. Estimator/Transformer just passthrough these columns without any modifications.

Returns:

self

set_sample_weight_col(sample_weight_col: Optional[str]) Base

Sample weight column setter.

Parameters:

sample_weight_col – A single column that represents sample weight.

Returns:

self

to_lightgbm() Any
to_sklearn() Any
to_xgboost() Any
transform(dataset: Union[DataFrame, DataFrame]) Union[DataFrame, DataFrame]

Transform dataset to ordinal codes.

Parameters:

dataset – Input dataset.

Returns:

Output dataset.