create submodule for polars

CHANGELOG.md

@@ -1,7 +1,7 @@
 # Changelog
 
 ## [Unreleased]
--  [ENH] Add `make_clean_names` function which works on a pandas Index/Series, a Polars Expression, or a python string/list. Issue #1343
+-  [ENH] Added a `clean_names` method for polars - it can be used to clean the column names, or clean column values . Issue #1343
 
 ## [v0.27.0] - 2024-03-21
 

janitor/functions/__init__.py

@@ -81,7 +81,6 @@
     col,
     get_columns,
     get_index_labels,
-    make_clean_names,
     patterns,
     unionize_dataframe_categories,
 )
@@ -130,7 +129,6 @@
     "join_apply",
     "label_encode",
     "limit_column_characters",
-    "make_clean_names",
     "min_max_scale",
     "move",
     "pivot_longer",

janitor/functions/clean_names.py

@@ -1,15 +1,16 @@
 """Functions for cleaning columns/index names and/or column values."""
 
+from __future__ import annotations
+
+import unicodedata
 from typing import Optional, Union
 
 import pandas as pd
 import pandas_flavor as pf
 from pandas.api.types import is_scalar
 
-from janitor.functions.utils import (
-    get_index_labels,
-    make_clean_names,
-)
+from janitor.errors import JanitorError
+from janitor.functions.utils import _is_str_or_cat, get_index_labels
 from janitor.utils import deprecated_alias
 
 
@@ -120,15 +121,14 @@ def clean_names(
             column_names = [column_names]
         df = df.copy()
         for column_name in column_names:
-            df[column_name] = make_clean_names(
+            df[column_name] = _clean_names(
                 obj=df[column_name],
                 enforce_string=enforce_string,
                 case_type=case_type,
                 remove_special=remove_special,
                 strip_accents=strip_accents,
                 strip_underscores=strip_underscores,
                 truncate_limit=truncate_limit,
-                object_type="pandas",
             )
         return df
 
@@ -141,31 +141,136 @@ def clean_names(
             for number in range(target_axis.nlevels)
         ]
         target_axis = [
-            make_clean_names(
+            _clean_names(
                 obj=obj,
                 enforce_string=enforce_string,
                 case_type=case_type,
                 remove_special=remove_special,
                 strip_accents=strip_accents,
                 strip_underscores=strip_underscores,
                 truncate_limit=truncate_limit,
-                object_type="pandas",
             )
             for obj in target_axis
         ]
     else:
-        target_axis = make_clean_names(
+        target_axis = _clean_names(
             obj=target_axis,
             enforce_string=enforce_string,
             case_type=case_type,
             remove_special=remove_special,
             strip_accents=strip_accents,
             strip_underscores=strip_underscores,
             truncate_limit=truncate_limit,
-            object_type="pandas",
         )
     # Store the original column names, if enabled by user
     if preserve_original_labels:
         df.__dict__["original_labels"] = getattr(df, axis)
     setattr(df, axis, target_axis)
     return df
+
+
+def _clean_names(
+    obj: Union[pd.Index, pd.Series],
+    strip_underscores: Optional[Union[str, bool]] = None,
+    case_type: str = "lower",
+    remove_special: bool = False,
+    strip_accents: bool = False,
+    enforce_string: bool = False,
+    truncate_limit: int = None,
+) -> Union[pd.Index, pd.Series]:
+    """
+    Generic function to clean labels in a pandas object.
+    """
+    if enforce_string and not (_is_str_or_cat(obj)):
+        obj = obj.astype(str)
+    obj = _change_case(obj=obj, case_type=case_type)
+    obj = _normalize_1(obj=obj)
+    if remove_special:
+        obj = obj.str.replace(
+            pat="[^A-Za-z_\\d]", repl="", regex=True
+        ).str.strip()
+    if strip_accents:
+        obj = _strip_accents(obj=obj)
+    obj = obj.str.replace(pat="_+", repl="_", regex=True)
+    obj = _strip_underscores_func(
+        obj,
+        strip_underscores=strip_underscores,
+    )
+    if truncate_limit:
+        obj = obj.str[:truncate_limit]
+    return obj
+
+
+def _change_case(
+    obj: Union[pd.Index, pd.Series],
+    case_type: str,
+) -> Union[pd.Index, pd.Series]:
+    """Change case of labels in obj."""
+    case_types = {"preserve", "upper", "lower", "snake"}
+    case_type = case_type.lower()
+    if case_type not in case_types:
+        raise JanitorError(f"case_type must be one of: {case_types}")
+
+    if case_type == "preserve":
+        return obj
+    if case_type == "upper":
+        return obj.str.upper()
+    if case_type == "lower":
+        return obj.str.lower()
+    # Implementation taken from: https://gist.github.com/jaytaylor/3660565
+    # by @jtaylor
+    return (
+        obj.str.replace(pat=r"(.)([A-Z][a-z]+)", repl=r"\1_\2", regex=True)
+        .str.replace(pat=r"([a-z0-9])([A-Z])", repl=r"\1_\2", regex=True)
+        .str.lower()
+    )
+
+
+def _normalize_1(
+    obj: Union[pd.Index, pd.Series]
+) -> Union[pd.Index, pd.Series]:
+    """Perform normalization of labels in obj."""
+    FIXES = [(r"[ /:,?()\.-]", "_"), (r"['’]", ""), (r"[\xa0]", "_")]
+    for search, replace in FIXES:
+        obj = obj.str.replace(pat=search, repl=replace, regex=True)
+
+    return obj
+
+
+def _strip_accents(
+    obj: Union[pd.Index, pd.Series],
+) -> Union[pd.Index, pd.Series]:
+    """Remove accents from a label.
+
+    Inspired from [StackOverflow][so].
+
+    [so]: https://stackoverflow.com/questions/517923/what-is-the-best-way-to-remove-accents-in-a-python-unicode-strin
+    """  # noqa: E501
+    return obj.map(
+        lambda f: "".join(
+            [
+                letter
+                for letter in unicodedata.normalize("NFD", str(f))
+                if not unicodedata.combining(letter)
+            ]
+        )
+    )
+
+
+def _strip_underscores_func(
+    obj: Union[pd.Index, pd.Series],
+    strip_underscores: Union[str, bool] = None,
+) -> Union[pd.Index, pd.Series]:
+    """Strip underscores."""
+    underscore_options = {None, "left", "right", "both", "l", "r", True}
+    if strip_underscores not in underscore_options:
+        raise JanitorError(
+            f"strip_underscores must be one of: {underscore_options}"
+        )
+    if strip_underscores in {"left", "l"}:
+        return obj.str.lstrip("_")
+    if strip_underscores in {"right", "r"}:
+        return obj.str.rstrip("_")
+    if strip_underscores in {True, "both"}:
+        return obj.str.strip("_")
+    return obj