"""Helpful preprocessing utilities."""
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.
Args:
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. Defaults to None.
drop (list): List of columns to drop. Defaults to None.
verbose (bool): If True, prints information about features and target. Defaults to True.
**kwargs: Other keyword arguments that should be passed to panda's `read_csv` method.
Returns:
pd.DataFrame, pd.Series: 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))
return infer_feature_types(X), infer_feature_types(y)
[docs]def split_data(
X, y, problem_type, problem_configuration=None, test_size=0.2, random_seed=0
):
"""Split data into train and test sets.
Args:
X (pd.DataFrame or np.ndarray): data of shape [n_samples, n_features]
y (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 time_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:
pd.DataFrame, pd.DataFrame, pd.Series, pd.Series: Feature and target data each split into train and test sets.
Examples:
>>> X = pd.DataFrame([1, 2, 3, 4, 5, 6], columns=["First"])
>>> y = pd.Series([8, 9, 10, 11, 12, 13])
...
>>> X_train, X_validation, y_train, y_validation = split_data(X, y, "regression", random_seed=42)
>>> X_train
First
5 6
2 3
4 5
3 4
>>> X_validation
First
0 1
1 2
>>> y_train
5 13
2 10
4 12
3 11
dtype: int64
>>> y_validation
0 8
1 9
dtype: int64
"""
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, y))
X_train = X.ww.iloc[train]
X_test = X.ww.iloc[test]
y_train = y.ww.iloc[train]
y_test = y.ww.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.
Args:
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.
Example:
>>> X = pd.DataFrame()
>>> X["integers"] = [i for i in range(10)]
>>> X["floats"] = [float(i) for i in range(10)]
>>> X["strings"] = [str(i) for i in range(10)]
>>> X["booleans"] = [bool(i%2) for i in range(10)]
Lists the number of columns corresponding to each dtype.
>>> number_of_features(X.dtypes)
Number of Features
Boolean 1
Categorical 1
Numeric 2
"""
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.
Args:
targets (pd.Series): Target data.
Returns:
pd.Series: Target data and their frequency distribution as percentages.
Examples:
>>> y = pd.Series([1, 2, 4, 1, 3, 3, 1, 2])
>>> target_distribution(y)
Targets
1 37.50%
2 25.00%
3 25.00%
4 12.50%
dtype: object
>>> y = pd.Series([True, False, False, False, True])
>>> target_distribution(y)
Targets
False 60.00%
True 40.00%
dtype: object
"""
distribution = targets.value_counts() / len(targets)
return distribution.mul(100).apply("{:.2f}%".format).rename_axis("Targets")