//  [python]
def structured_preprocessor(data, ca_threshold=0.5, text=[]):
    '''
    structured preprocessing function that's called in the case that the user doesn't provide a preprocessing option, called after the initial changes
    :param data: dataframe
    :param ca_threshold: is correspondence analysis threshold for removing columns
    :param text: textual columns that require preprocessing by lemmatization, tokenization
    :return preprocessed dataframe
    '''

    # Preprocessing for datetime columns
    process_dates(data)

    # This will be used inside process_text once complete
    if len(text) > 0:
        text_preprocessing(data, text)

    # identifies the categorical and numerical columns
    categorical_columns = data['train'].select_dtypes(
        exclude=["number"]).columns
    numeric_columns = data['train'].columns[data['train'].dtypes.apply(
        lambda c: np.issubdtype(c, np.number))]

    # Removes text columns from categorical columns to use in separate pipeline
    categorical_columns = [
        cat_cols for cat_cols in categorical_columns if cat_cols not in text]

    full_pipeline = ColumnTransformer([], remainder="passthrough")

    if len(numeric_columns) != 0:
        # pipeline for numeric columns
        num_pipeline = Pipeline([
            ('imputer', Imputer(strategy="median")),
            ('std_scaler', StandardScaler())
        ])

        full_pipeline.transformers.append(
            ("num", num_pipeline, numeric_columns))

    if len(text) != 0:
        # Each text col needs a separate pipeline
        for x in range(len(text)):
            full_pipeline.transformers.append(
                (f"text_{x}",
                 Pipeline(
                     [
                         ('test',
                          FunctionTransformer(
                              lambda x: np.reshape(
                                  x.to_numpy(),
                                  (-1,
                                   1)))),
                         ('imputer',
                          Imputer(
                              strategy="constant",
                              fill_value="")),
                         ('raveler',
                          FunctionTransformer(
                              lambda x: x.ravel(),
                              accept_sparse=True)),
                         ('vect',
                          TfidfVectorizer()),
                         ('densifier',
                          FunctionTransformer(
                              lambda x: x.todense(),
                              accept_sparse=True)),
                         ('embedder',
                          FunctionTransformer(
                              textembedder,
                              accept_sparse=True))]),
                 text[x]))

    if len(categorical_columns) != 0:
        combined = pd.concat([data['train'], data['test']], axis=0)

        ca_threshold = combined.shape[0] * \
                       .25 if ca_threshold is None else combined.shape[0] * ca_threshold

        if too_many_values(combined[categorical_columns], ca_threshold):
            cat_pipeline = Pipeline([
                ('imputer', Imputer(strategy="constant", fill_value="")),
                ('one_hotencoder', OneHotEncoder(handle_unknown='ignore')),
                ('transformer', FunctionTransformer(lambda x: x.toarray(), accept_sparse=True)),
                ('ca', CA(n_components=-1))
            ])
        else:
            cat_pipeline = Pipeline([
                ('imputer', Imputer(strategy="constant", fill_value="")),
                ('label_enconder', LabelEncoder())
            ])

        full_pipeline.transformers.append(
            ('cat', cat_pipeline, categorical_columns))

    train = full_pipeline.fit_transform(data['train'])

    train_cols = generate_column_labels(full_pipeline, numeric_columns, text)

    test = full_pipeline.transform(data['test'])

    test_cols = generate_column_labels(full_pipeline, numeric_columns, text)

    # Ternary clause because when running housing.csv,
    # the product of preprocessing is np array, but not when using landslide
    # data... not sure why
    data['train'] = pd.DataFrame(
        (train.toarray() if not isinstance(
            train,
            np.ndarray) else train),
        columns=train_cols)
    data['test'] = pd.DataFrame(
        (test.toarray() if not isinstance(
            test,
            np.ndarray) else test),
        columns=test_cols)
    return data, full_pipeline