import pandas as pd
from sklearn.model_selection import ShuffleSplit, StratifiedShuffleSplit
from evalml.preprocessing.data_splitters import TrainingValidationSplit
from evalml.problem_types import (
is_classification,
is_regression,
is_time_series
)
from evalml.utils import infer_feature_types
[docs]def load_data(path, index, target, n_rows=None, drop=None, verbose=True, **kwargs):
"""Load features and target from file.
Arguments:
path (str): Path to file or a http/ftp/s3 URL
index (str): Column for index
target (str): Column for target
n_rows (int): Number of rows to return
drop (list): List of columns to drop
verbose (bool): If True, prints information about features and target
Returns:
ww.DataTable, ww.DataColumn: Features matrix and target
"""
feature_matrix = pd.read_csv(path, index_col=index, nrows=n_rows, **kwargs)
targets = [target] + (drop or [])
y = feature_matrix[target]
X = feature_matrix.drop(columns=targets)
if verbose:
# number of features
print(number_of_features(X.dtypes), end='\n\n')
# number of total training examples
info = 'Number of training examples: {}'
print(info.format(len(X)), end='\n')
# target distribution
print(target_distribution(y))
X = infer_feature_types(X)
y = infer_feature_types(y)
return X, y
[docs]def split_data(X, y, problem_type, problem_configuration=None, test_size=.2, random_seed=0):
"""Splits data into train and test sets.
Arguments:
X (ww.DataTable, pd.DataFrame or np.ndarray): data of shape [n_samples, n_features]
y (ww.DataColumn, pd.Series, or np.ndarray): target data of length [n_samples]
problem_type (str or ProblemTypes): type of supervised learning problem. see evalml.problem_types.problemtype.all_problem_types for a full list.
problem_configuration (dict): Additional parameters needed to configure the search. For example,
in time series problems, values should be passed in for the date_index, gap, and max_delay variables.
test_size (float): What percentage of data points should be included in the test set. Defaults to 0.2 (20%).
random_seed (int): Seed for the random number generator. Defaults to 0.
Returns:
ww.DataTable, ww.DataTable, ww.DataColumn, ww.DataColumn: Feature and target data each split into train and test sets
"""
X = infer_feature_types(X)
y = infer_feature_types(y)
data_splitter = None
if is_time_series(problem_type):
data_splitter = TrainingValidationSplit(test_size=test_size, shuffle=False, stratify=None, random_seed=random_seed)
elif is_regression(problem_type):
data_splitter = ShuffleSplit(n_splits=1, test_size=test_size, random_state=random_seed)
elif is_classification(problem_type):
data_splitter = StratifiedShuffleSplit(n_splits=1, test_size=test_size, random_state=random_seed)
train, test = next(data_splitter.split(X.to_dataframe(), y.to_series()))
X_train = X.iloc[train]
X_test = X.iloc[test]
y_train = y.iloc[train]
y_test = y.iloc[test]
return X_train, X_test, y_train, y_test
[docs]def number_of_features(dtypes):
"""Get the number of features of each specific dtype in a DataFrame.
Arguments:
dtypes (pd.Series): DataFrame.dtypes to get the number of features for
Returns:
pd.Series: dtypes and the number of features for each input type
"""
dtype_to_vtype = {
'bool': 'Boolean',
'int32': 'Numeric',
'int64': 'Numeric',
'float64': 'Numeric',
'object': 'Categorical',
'datetime64[ns]': 'Datetime',
}
vtypes = dtypes.astype(str).map(dtype_to_vtype).value_counts()
return vtypes.sort_index().to_frame('Number of Features')
[docs]def target_distribution(targets):
"""Get the target distributions.
Arguments:
targets (pd.Series): Target data
Returns:
pd.Series: Target data and their frequency distribution as percentages.
"""
distribution = targets.value_counts() / len(targets)
return distribution.mul(100).apply('{:.2f}%'.format).rename_axis('Targets')
[docs]def drop_nan_target_rows(X, y):
"""Drops rows in X and y when row in the target y has a value of NaN.
Arguments:
X (pd.DataFrame, np.ndarray): Data to transform
y (pd.Series, np.ndarray): Target data
Returns:
pd.DataFrame, pd.DataFrame: Transformed X (and y, if passed in) with rows that had a NaN value removed.
"""
X_t = X
y_t = y
if not isinstance(X_t, pd.DataFrame):
X_t = pd.DataFrame(X_t)
if not isinstance(y_t, pd.Series):
y_t = pd.Series(y_t)
# drop rows where corresponding y is NaN
y_null_indices = y_t.index[y_t.isna()]
X_t = X_t.drop(index=y_null_indices)
y_t.dropna(inplace=True)
return X_t, y_t