def robust_scale(df, quantile_range=(25.0, 75.0)):
rbs = RobustScaler(with_centering=True,
with_scaling=True,
quantile_range=quantile_range,
copy=True)
num_cols = utl.get_numerical_columns(df)
df[num_cols] = rbs.fit_transform(df[num_cols])
return df
def box_cox_transform(df, include_missing_value=False):
num_cols = utl.get_numerical_columns(df)
if include_missing_value:
pos_cols = [c for c in num_cols if ~(df[c] <= 0.0).all()]
else:
pos_cols = [c for c in num_cols if (df[c] > 0.0).all()]
pt = PowerTransformer(method='box-cox')
df[pos_cols] = pt.fit_transform(df[pos_cols])
return df
def fit_transform(self, df):
df = df.copy()
if self.method == 'standard':
self.scaling_cols = utl.get_columns_for_std(df)
if self.method == 'yeo-johnson':
self.scaling_cols = utl.get_numerical_columns(df)
df.loc[:, self.scaling_cols] = self.scaler.fit_transform(
df[self.scaling_cols])
return df
def minimax_scale(df):
"""
Transform features by scaling each feature to a given range.
Notion:
- The averages are not always 0
- Easily affected by outlier
"""
mms = MinMaxScaler()
num_cols = utl.get_numerical_columns(df)
df[num_cols] = mms.fit_transform(df[num_cols])
return df
def rank_transform(df, method='average'):
"""
Assign ranks to df, dealing with ties appropriately.
Parameters:
df : array_like
The array of values to be ranked.
The array is first flattened.
method : str, optional
The method used to assign ranks to tied elements.
The options are ‘average’, ‘min’, ‘max’, ‘dense’
and ‘ordinal’.
‘average’:
The average of the ranks that would have been assigned to all
the tied values is assigned to each value.
‘min’:
The minimum of the ranks that would have been assigned to all
the tied values is assigned to each value. (This is also
referred to as “competition” ranking.)
‘max’:
The maximum of the ranks that would have been assigned to all
the tied values is assigned to each value.
‘dense’:
Like ‘min’, but the rank of the next highest element is
assigned the rank immediately after those assigned to the
tied elements.
‘ordinal’:
All values are given a distinct rank, corresponding to the
order that the values occur in a.
Returns:
ranks : ndarray
An array of length equal to the size of a, containing rank
scores.
[Notion]
- Apply to train df and test df together
"""
num_cols = utl.get_numerical_columns(df)
df[num_cols] = stats.rankdata(df[num_cols], method)
return df
def uniform_transform(df,
n_quantiles=1000,
ignore_implicit_zeros=False,
subsample=100000,
random_state=None,
copy=True):
qt = QuantileTransformer(n_quantiles=n_quantiles,
output_distribution='uniform',
ignore_implicit_zeros=ignore_implicit_zeros,
subsample=subsample,
random_state=random_state,
copy=copy)
num_cols = utl.get_numerical_columns(df)
df[num_cols] = qt.fit_transform(df[num_cols])
return df
def yeo_johnson_transform(df):
num_cols = utl.get_numerical_columns(df)
pt = PowerTransformer(method='yeo-johnson')
df[num_cols] = pt.fit_transform(df[num_cols])
return df
def log_abs_transform(df):
num_cols = utl.get_numerical_columns(df)
x = df[num_cols].copy()
df[num_cols] = np.sign(x) * np.log(np.abs(x))
return df
