Data Preparer and PreparerSteps base class and Data Cleaner(#98)

Data Preparer and PreparerSteps base class and Data Cleaner

foreshadow/cleaners/__init__.py

@@ -1 +1,10 @@
 """Cleaner module for handling the cleaning and shaping of data."""
+
+from foreshadow.cleaners.data_cleaner import (
+    DataCleaner,
+    SmartCleaner,
+    SmartFlatten,
+)
+
+
+__all__ = ["SmartCleaner", "DataCleaner", "SmartFlatten"]

foreshadow/cleaners/data_cleaner.py

@@ -1,26 +1,323 @@
 """Cleaner module for cleaning data as step in Foreshadow workflow."""
+from collections import namedtuple
+
+import pandas as pd
 from sklearn.base import BaseEstimator, TransformerMixin
 
+from foreshadow.core.preparerstep import PreparerStep
+from foreshadow.exceptions import InvalidDataFrame
+from foreshadow.metrics.internals import avg_col_regex, regex_rows
+from foreshadow.transformers.core import SmartTransformer
+from foreshadow.transformers.core.notransform import NoTransform
+from foreshadow.utils.testing import dynamic_import
+from foreshadow.utils.validation import check_df
+
+
+CleanerReturn = namedtuple("CleanerReturn", ["row", "match_lens"])
+
+
+class DataCleaner(PreparerStep):
+    """Determine and perform best data cleaning step."""
+
+    def __init__(self, *args, **kwargs):
+        """Define the single step for DataCleaner, using SmartCleaner.
+
+        Args:
+            *args: args to PreparerStep constructor.
+            **kwargs: kwargs to PreparerStep constructor.
+
+        """
+        super().__init__(*args, use_single_pipeline=True, **kwargs)
+
+    def get_mapping(self, X):
+        """Return the mapping of transformations for the DataCleaner step.
 
-class DataCleaner(BaseEstimator, TransformerMixin):
-    """Wrapper class to determine and perform best data cleaning step."""
+        Args:
+            X: input DataFrame.
+
+        Returns:
+            Mapping in accordance with super.
+
+        """
+        return self.separate_cols(
+            transformers=[
+                [
+                    SmartFlatten(column_sharer=self.column_sharer),
+                    SmartCleaner(column_sharer=self.column_sharer),
+                ]
+                for c in X
+            ],
+            X=X,
+        )
+
+
+class SmartCleaner(SmartTransformer):
+    """Intelligently decide which cleaning function should be applied."""
 
     def __init__(self, **kwargs):
-        """Stub init method.
+        super().__init__(**kwargs)
+
+    def pick_transformer(self, X, y=None, **fit_params):
+        """Get best transformer for a given column.
 
         Args:
-            **kwargs: placeholder.
+            X: input DataFrame
+            y: input labels
+            **fit_params: fit_params
+
+        Returns:
+            Best data cleaning transformer.
 
         """
-        super().__init__()
+        from foreshadow.cleaners.internals import __all__ as cleaners
+
+        cleaners = [
+            (dynamic_import(cleaner, "foreshadow.cleaners.internals"), cleaner)
+            for cleaner in cleaners
+            if cleaner.lower().find("cleaner") != -1
+        ]
+        best_score = 0
+        best_cleaner = None
+        for cleaner, name in cleaners:
+            cleaner = cleaner(column_sharer=self.column_sharer, name=name)
+            score = cleaner.metric_score(X)
+            if score > best_score:
+                best_score = score
+                best_cleaner = cleaner
+
+        if best_cleaner is None:
+            return NoTransform(column_sharer=self.column_sharer)
+        return best_cleaner
 
-    def fit(self, X, y=None, **fit_params):
-        """Stub fit method.
+
+class SmartFlatten(SmartTransformer):
+    """Smartly determine how to flatten an input DataFrame."""
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+
+    def pick_transformer(self, X, y=None, **fit_params):
+        """Get best transformer for a given column.
 
         Args:
-            X: input data
-            y: labels
-            **fit_params: params to fit method.
+            X: input DataFrame
+            y: input labels
+            **fit_params: fit_params
+
+        Returns:
+            Best data flattening transformer
 
         """
-        pass
+        from foreshadow.cleaners.internals import __all__ as flatteners
+
+        flatteners = [
+            (
+                dynamic_import(flattener, "foreshadow.cleaners.internals"),
+                flattener,
+            )
+            for flattener in flatteners
+            if flattener.lower().find("flatten") != -1
+        ]
+
+        best_score = 0
+        best_flattener = None
+        for flattener, name in flatteners:
+            flattener = flattener(column_sharer=self.column_sharer, name=name)
+            score = flattener.metric_score(X)
+            if score > best_score:
+                best_score = score
+                best_flattener = flattener
+
+        if best_flattener is None:
+            return NoTransform(column_sharer=self.column_sharer)
+        return best_flattener
+
+
+class BaseCleaner(BaseEstimator, TransformerMixin):
+    """Base class for any Cleaner Transformer."""
+
+    def __init__(
+        self,
+        transformations,
+        output_columns=None,
+        confidence_computation=None,
+        default=lambda x: x,
+    ):
+        """Construct any cleaner/flattener.
+
+        Args:
+            transformations: a callable that takes a string and returns a
+                tuple with the length of the transformed characters and then
+                transformed string.
+            output_columns: If none, any lists returned by the transformations
+                are assumed to be separate columns in the new DataFrame.
+                Otherwise, pass the names for each desired output
+                column to be used.
+            confidence_computation: The dict of {metric: weight} for the
+                subclass's metric computation. This implies an OVR model.
+            default: Function that returns the default value for a row if
+                the transformation failed. Accepts the row as input.
+
+        Raises:
+            ValueError: If not a list, int, or None specifying expected
+                output columns.
+
+        """
+        if not isinstance(output_columns, (int, list, type(None))):
+            raise ValueError("output columns not a valid type")
+
+        self.default = default
+        self.output_columns = output_columns
+        self.transformations = transformations
+        self.confidence_computation = {regex_rows: 0.8, avg_col_regex: 0.2}
+        if confidence_computation is not None:
+            self.confidence_computation = confidence_computation
+
+    def metric_score(self, X):
+        """Compute the score for this cleaner using confidence_computation.
+
+        confidence_computation is passed through init for each subclass.
+        The confidence determines which cleaner/flattener is picked in an
+        OVR fashion.
+
+        Args:
+            X: input DataFrame.
+
+        Returns:
+            float: confidence value.
+
+        """
+        return sum(
+            [
+                metric_fn(X, cleaner=self.transform_row) * weight
+                for metric_fn, weight in self.confidence_computation.items()
+            ]
+        )
+
+    def transform_row(self, row_of_feature, return_tuple=True):
+        """Perform clean operations on text, that is a row of feature.
+
+        Uses self.transformations determined at init time by the child class
+        and performs the transformations sequentially.
+
+        Args:
+            row_of_feature: one row of one column
+            return_tuple: return named_tuple object instead of just the row.
+                This will often be set to False when passing this method to an
+                external function (non source code) that will expect the
+                output to only be the transformed row, such as DataFrame.apply.
+
+        Returns:
+            NamedTuple object with:
+            .text
+            the text in row_of_feature transformed by transformations. If
+            not possible, it will be None.
+            .match_lens
+            the number of characters from original text at each step that
+            was transformed.
+
+        """
+        matched_lengths = []  # this does not play nice with creating new
+        # columns
+        for transform in self.transformations:
+            row = row_of_feature
+            row, match_len = transform(row)
+            if match_len == 0:
+                matched_lengths.append(0)
+                row = self.default(row_of_feature)
+                break
+            matched_lengths.append(match_len)
+        if return_tuple:
+            return CleanerReturn(row, matched_lengths)
+        else:
+            return row
+
+    def fit(self, X, y=None):
+        """Empty fit.
+
+        Args:
+            X: input observations
+            y: input labels
+
+        Returns:
+            self
+
+        """
+        return self
+
+    def transform(self, X, y=None):
+        """Clean string columns.
+
+        Here, we assume that any list output means that these are desired
+        to be new columns in our dataset. Contractually, this could change
+        to be that a boolean flag is passed to indicate when this is
+        desired, as of right now, there should be no need to return a list
+        for any case other than this case of desiring new column.
+
+        The same is assumed for dicts, where the key is the new column name,
+        the value is the value for that row in that column. NaNs
+        are automatically put into the columns that don't exist for given rows.
+
+        Args:
+            X (:obj:`pandas.Series`): X data
+            y: input labels
+
+        Returns:
+            :obj:`pandas.DataFrame`: Transformed data
+
+        Raises:
+            InvalidDataFrame: If unexpected output returned that was not
+                handled correctly. This happens if the output specified by the
+                child does not match what is actually returned. The child
+                should ensure it's implementation is consistent.
+
+        """
+        X = check_df(X, single_column=True)
+        # Problem:
+        # I can use .apply to perform all these transformations and that
+        # works beautifully, except when I want to define a funtion that
+        # will use the pandas.series.str.split operation. In which case,
+        # the .apply fails and I don't know why.
+
+        # I need each function to accept the row as an argument so that we
+        # can inspect how much of the text was matched (for determining if
+        # it should be used). however, doing this means I need to iterate
+        # over each row for a given column on my own, which requires me to
+        # leave
+
+        out = X[X.columns[0]].apply(self.transform_row, return_tuple=False)
+        # access single column as series and apply the list of
+        # transformations to each row in the series.
+        if any(
+            [isinstance(out[i], (list, tuple)) for i in range(out.shape[0])]
+        ):  # out are lists == new columns
+            if not all(
+                [len(out[0]) == len(out[i]) for i in range(len(out[0]))]
+            ):
+                raise InvalidDataFrame(
+                    "length of lists: {}, returned not of same value.".format(
+                        [out[i] for i in range(len(out[0]))]
+                    )
+                )
+            columns = self.output_columns
+            if columns is None:
+                columns = [X.columns[0] + str(c) for c in range(len(out[0]))]
+                # by default, pandas would have given a unique integer to
+                # each column, instead, we keep the previous column name and
+                # add that integer.
+            X = pd.DataFrame([*out.values], columns=columns)
+        elif any(
+            [isinstance(out[i], (dict)) for i in range(out.shape[0])]
+        ):  # out are dicts ==  named new columns
+            all_keys = dict()
+            for row in out:
+                all_keys.update({key: True for key in row})  # get all columns
+            columns = list(all_keys.keys())
+            out = pd.DataFrame([*out.values], columns=columns)
+            out.columns = [X.columns[0] + "_" + c for c in columns]
+            X = out
+            # by default, this will create a DataFrame where if a row
+            # contains the value, it will be added, if not NaN is added.
+        else:  # no lists, still 1 column output
+            X[X.columns[0]] = out
+        return X

foreshadow/cleaners/internals/__init__.py

@@ -0,0 +1,37 @@
+"""Internal cleaners for handling the cleaning and shaping of data."""
+
+import glob
+import inspect
+import os
+
+from foreshadow.transformers.core import _get_modules
+
+
+def _get_classes():
+    """Return list of classes found in cleaners directory.
+
+    Returns:
+        list of classes found in cleaners directory
+
+    """
+    files = glob.glob(os.path.dirname(__file__) + "/*.py")
+    imports = [
+        os.path.basename(f)[:-3]
+        for f in files
+        if os.path.isfile(f) and not f.endswith("__init__.py")
+    ]
+    modules = [
+        __import__(i, globals(), locals(), ["object"], 1) for i in imports
+    ]
+    classes = [
+        c[1]
+        for m in modules
+        for c in inspect.getmembers(m)
+        if inspect.isclass(c[1]) and c[1].__name__.find("Base") == -1
+    ]
+
+    return classes
+
+
+classes = _get_modules(_get_classes(), globals(), __name__)
+__all__ = classes