def value_counts(self,
normalize=False,
sort=True,
ascending=False,
bins=None,
dropna=True):
if bins is not None:
raise NotImplementedError(
"value_counts currently does not support bins")
if dropna:
df_dropna = self.to_dataframe()._spark_filter(self.notna())
else:
df_dropna = self.to_dataframe()
df = df_dropna._spark_groupby(self).count()
if sort:
if ascending:
df = df._spark_orderBy(F._spark_col('count'))
else:
df = df._spark_orderBy(F._spark_col('count')._spark_desc())
if normalize:
sum = df_dropna._spark_count()
df = df._spark_withColumn(
'count',
F._spark_col('count') / F._spark_lit(sum))
return _col(df.set_index([self.name]))
def value_counts(self,
normalize=False,
sort=True,
ascending=False,
bins=None,
dropna=True):
if bins is not None:
raise NotImplementedError(
"value_counts currently does not support bins")
if dropna:
df_dropna = self._pandas_anchor._spark_filter(self.notna())
else:
df_dropna = self._pandas_anchor
df = df_dropna._spark_groupby(self).count()
if sort:
if ascending:
df = df._spark_orderBy(F._spark_col('count'))
else:
df = df._spark_orderBy(F._spark_col('count')._spark_desc())
if normalize:
sum = df_dropna._spark_count()
df = df._spark_withColumn(
'count',
F._spark_col('count') / F._spark_lit(sum))
index_name = 'index' if self.name != 'index' else 'level_0'
df.columns = [index_name, self.name]
df._metadata = Metadata(column_fields=[self.name],
index_info=[(index_name, None)])
return _col(df)
def __setitem__(self, key, value):
from databricks.koalas.frame import DataFrame
from databricks.koalas.series import Series
if (not isinstance(key, tuple)) or (len(key) != 2):
raise NotImplementedError("Only accepts pairs of candidates")
rows_sel, cols_sel = key
if (not isinstance(rows_sel, slice)) or (rows_sel != slice(None)):
raise SparkPandasNotImplementedError(
description=
"""Can only assign value to the whole dataframe, the row index
has to be `slice(None)` or `:`""",
pandas_function=".loc[..., ...] = ...",
spark_target_function="withColumn, select")
if not isinstance(cols_sel, str):
raise ValueError("""only column names can be assigned""")
if isinstance(value, Series):
self._kdf[cols_sel] = value
elif isinstance(value, DataFrame) and len(value.columns) == 1:
from pyspark.sql.functions import _spark_col
self._kdf[cols_sel] = _spark_col(value.columns[0])
elif isinstance(value, DataFrame) and len(value.columns) != 1:
raise ValueError(
"Only a dataframe with one column can be assigned")
else:
raise ValueError(
"Only a column or dataframe with single column can be assigned"
)
def __setitem__(self, key, value):
from databricks.koalas.frame import DataFrame
from databricks.koalas.series import Series
if (not isinstance(key, tuple)) or (len(key) != 2):
raise NotImplementedError("Only accepts pairs of candidates")
rows_sel, cols_sel = key
if (not isinstance(rows_sel, slice)) or (rows_sel != slice(None)):
raise SparkPandasNotImplementedError(
description="""Can only assign value to the whole dataframe, the row index
has to be `slice(None)` or `:`""",
pandas_function=".loc[..., ...] = ...",
spark_target_function="withColumn, select")
if not isinstance(cols_sel, str):
raise ValueError("""only column names can be assigned""")
if isinstance(value, Series):
self._kdf[cols_sel] = value
elif isinstance(value, DataFrame) and len(value.columns) == 1:
from pyspark.sql.functions import _spark_col
self._kdf[cols_sel] = _spark_col(value.columns[0])
elif isinstance(value, DataFrame) and len(value.columns) != 1:
raise ValueError("Only a dataframe with one column can be assigned")
else:
raise ValueError("Only a column or dataframe with single column can be assigned")
def _make_col(c):
if isinstance(c, Column):
return c
elif isinstance(c, str):
from pyspark.sql.functions import _spark_col
return _spark_col(c)
else:
raise SparkPandasNotImplementedError(
description="Can only convert a string to a column type.")
def get_dummies(data, prefix=None, prefix_sep='_', dummy_na=False, columns=None, sparse=False,
drop_first=False, dtype=None):
if sparse is not False:
raise NotImplementedError("get_dummies currently does not support sparse")
if isinstance(columns, string_types):
columns = [columns]
if dtype is None:
dtype = 'byte'
if isinstance(data, Column):
if prefix is not None:
prefix = [str(prefix)]
columns = [data.name]
df = data.to_dataframe()
remaining_columns = []
else:
if isinstance(prefix, string_types):
raise ValueError("get_dummies currently does not support prefix as string types")
df = data.copy()
if columns is None:
columns = [column for column in df.columns
if isinstance(data.schema[column].dataType,
_get_dummies_default_accept_types)]
if len(columns) == 0:
return df
if prefix is None:
prefix = columns
column_set = set(columns)
remaining_columns = [df[column] for column in df.columns if column not in column_set]
if any(not isinstance(data.schema[column].dataType, _get_dummies_acceptable_types)
for column in columns):
raise ValueError("get_dummies currently only accept {} values"
.format(', '.join([t.typeName() for t in _get_dummies_acceptable_types])))
if prefix is not None and len(columns) != len(prefix):
raise ValueError(
"Length of 'prefix' ({}) did not match the length of the columns being encoded ({})."
.format(len(prefix), len(columns)))
all_values = _reduce_spark_multi(df, [F._spark_collect_set(F._spark_col(column))
._spark_alias(column)
for column in columns])
for i, column in enumerate(columns):
values = sorted(all_values[i])
if drop_first:
values = values[1:]
def column_name(value):
if prefix is None:
return str(value)
else:
return '{}{}{}'.format(prefix[i], prefix_sep, value)
for value in values:
remaining_columns.append((df[column].notnull() & (df[column] == value))
.astype(dtype)
.alias(column_name(value)))
if dummy_na:
remaining_columns.append(df[column].isnull().astype(dtype).alias(column_name('nan')))
return df[remaining_columns]
