def z_score(df, columns, threshold=None):
"""
Delete outlier using z score
:param df:
:param columns:
:param threshold:
:return:
"""
if not is_dataframe(df):
raise TypeError("Spark Dataframe expected")
if not is_int(threshold):
raise TypeError("Integer expected")
columns = parse_columns(df, columns)
for c in columns:
# the column with the z_col value is always the string z_col plus the name of column
z_col = "z_col_" + c
df = df.cols.z_score(c) \
.rows.drop(F.col(z_col) > threshold) \
.cols.drop(z_col)
return df
def rename(columns_old_new=None, func=None):
""""
Changes the name of a column(s) dataFrame.
:param columns_old_new: List of tuples. Each tuple has de following form: (oldColumnName, newColumnName).
:param func: can be lower, upper or any string transformation function
"""
df = self
# Apply a transformation function
if is_function(func):
exprs = [F.col(c).alias(func(c)) for c in df.columns]
df = df.select(exprs)
elif is_list_of_tuples(columns_old_new):
# Check that the 1st element in the tuple is a valid set of columns
validate_columns_names(self, columns_old_new)
for c in columns_old_new:
old_col_name = c[0]
if is_str(old_col_name):
df = df.withColumnRenamed(old_col_name, c[1])
elif is_int(old_col_name):
df = df.withColumnRenamed(self.schema.names[old_col_name], c[1])
return df
def _mad(self, action):
"""
:type action:
:return:
"""
df = self.df
columns = self.columns
threshold = self.threshold
if not is_dataframe(df):
raise TypeError("Spark Dataframe expected")
if not is_int(threshold):
raise TypeError("Integer expected")
columns = parse_columns(df, columns)
for c in columns:
mad_value = df.cols.mad(c, more=True)
lower_bound = mad_value["median"] - threshold * mad_value["mad"]
upper_bound = mad_value["median"] + threshold * mad_value["mad"]
if action is "select":
df = df.rows.select((F.col(c) > upper_bound)
| (F.col(c) < lower_bound))
elif action is "drop":
df = df.rows.drop((F.col(c) > upper_bound)
| (F.col(c) < lower_bound))
return df
def length_error(var1, var2):
"""
Raise a ValueError exception
:param var1:
:param var2:
:return:
"""
from optimus.helpers.functions import get_var_name
if is_int(var2):
length_var2 = str(var2)
else:
length_var2 = str(len(var2))
raise ValueError(
"'{var2_name}' must be length '{var1_length}', received '{var2_length}'"
.format(var2_name=get_var_name(var2),
var1_length=str(len(var1)),
var2_length=length_var2))
def mad(df, columns, threshold=None):
"""
Delete outlier using mad
:param df:
:param columns:
:param threshold:
:return:
"""
if not is_dataframe(df):
raise TypeError("Spark Dataframe expected")
if not is_int(threshold):
raise TypeError("Integer expected")
columns = parse_columns(df, columns)
for c in columns:
mad_value = df.cols.mad(c, more=True)
lower_bound = mad_value["median"] - threshold * mad_value["mad"]
upper_bound = mad_value["median"] + threshold * mad_value["mad"]
df = df.rows.drop((F.col(c) > upper_bound)
| (F.col(c) < lower_bound))
return df
def unnest(columns, mark=None, splits=None, index=None):
"""
Split an array or string in different columns
:param columns: Columns to be un-nested
:param mark: If column is string.
:param splits: Number of rows to un-nested. Because we can not know beforehand the number of splits
:param index:
:return: Spark DataFrame
"""
# If a number of split was not defined try to infer the length with the first element
infer_splits = None
if splits is None:
infer_splits = True
columns = parse_columns(self, columns)
df = self
for col_name in columns:
# if the col is array
col_dtype = self.schema[col_name].dataType
# Array
if is_(col_dtype, ArrayType):
expr = F.col(col_name)
# Try to infer the array length using the first row
if infer_splits is True:
splits = len(self.cols.cell(col_name))
for i in builtins.range(splits):
df = df.withColumn(col_name + "_" + str(i), expr.getItem(i))
# String
elif is_(col_dtype, StringType):
expr = F.split(F.col(col_name), mark)
# Try to infer the array length using the first row
if infer_splits is True:
splits = len(self.cols.cell(col_name).split(mark))
if is_int(index):
r = builtins.range(index, index + 1)
else:
r = builtins.range(0, splits)
for i in r:
df = df.withColumn(col_name + "_" + str(i), expr.getItem(i))
# Vector
elif is_(col_dtype, VectorUDT):
def _unnest(row):
_dict = row.asDict()
# Get the column we want to unnest
_list = _dict[col_name]
# Ensure that float are python floats and not np floats
if index is None:
_list = [float(x) for x in _list]
else:
_list = [float(_list[1])]
return row + tuple(_list)
df = df.rdd.map(_unnest).toDF(df.columns)
return df
def unnest(columns, mark=None, n=None, index=None):
"""
Split array or string in different columns
:param columns: Columns to be un-nested
:param mark: is column is string
:param n: Number of rows to un-nested
:param index:
:return: Spark DataFrame
"""
# If a number of split was not defined try to infer the lenght with the first element
infer_n = None
if n is None:
infer_n = True
columns = parse_columns(self, columns)
df = self
for col_name in columns:
# if the col is array
expr = None
col_dtype = self.schema[col_name].dataType
# Array
if is_(col_dtype, ArrayType):
expr = F.col(col_name)
# Try to infer the array length using the first row
if infer_n is True:
n = len(self.cols.cell(col_name))
for i in builtins.range(n):
df = df.withColumn(col_name + "_" + str(i),
expr.getItem(i))
# String
elif is_(col_dtype, StringType):
expr = F.split(F.col(col_name), mark)
# Try to infer the array length using the first row
if infer_n is True:
n = len(self.cols.cell(col_name).split(mark))
if is_int(index):
r = builtins.range(index, index + 1)
else:
r = builtins.range(0, n)
for i in r:
df = df.withColumn(col_name + "_" + str(i),
expr.getItem(i))
# Vector
elif is_(col_dtype, VectorUDT):
def extract(row):
return row + tuple(row.vector.toArray().tolist())
df = df.rdd.map(extract).toDF(df.columns)
return df
