def hashrightjoin(left, right, key=None, lkey=None, rkey=None, missing=None,
cache=True, lprefix=None, rprefix=None):
"""
Alternative implementation of :func:`rightjoin`, where the join is executed
by constructing an in-memory lookup for the left hand table, then iterating over rows
from the right hand table.
May be faster and/or more resource efficient where the left table is small
and the right table is large.
.. versionadded:: 0.5
.. versionchanged:: 0.16
Added support for caching data from left hand table (only available when
`key` is given).
.. versionchanged:: 0.24
Added support for left and right tables with different key fields via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashRightJoinView(left, right, lkey, rkey, missing=missing,
cache=cache, lprefix=lprefix, rprefix=rprefix)
def hashlookupjoin(left,
right,
key=None,
lkey=None,
rkey=None,
missing=None,
lprefix=None,
rprefix=None):
"""Alternative implementation of :func:`petl.transform.joins.lookupjoin`,
where the join is executed by constructing an in-memory lookup for the
right hand table, then iterating over rows from the left hand table.
May be faster and/or more resource efficient where the right table is small
and the left table is large.
Left and right tables with different key fields can be handled via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashLookupJoinView(left,
right,
lkey,
rkey,
missing=missing,
lprefix=lprefix,
rprefix=rprefix)
def hashrightjoin(left,
right,
key=None,
lkey=None,
rkey=None,
missing=None,
cache=True,
lprefix=None,
rprefix=None):
"""Alternative implementation of :func:`petl.transform.joins.rightjoin`,
where the join is executed by constructing an in-memory lookup for the
left hand table, then iterating over rows from the right hand table.
May be faster and/or more resource efficient where the left table is small
and the right table is large.
By default data from right hand table is cached to improve performance
(only available when `key` is given).
Left and right tables with different key fields can be handled via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashRightJoinView(left,
right,
lkey,
rkey,
missing=missing,
cache=cache,
lprefix=lprefix,
rprefix=rprefix)
def hashantijoin(left, right, key=None, lkey=None, rkey=None):
"""Alternative implementation of :func:`petl.transform.joins.antijoin`,
where the join is executed by constructing an in-memory set for all keys
found in the right hand table, then iterating over rows from the left
hand table.
May be faster and/or more resource efficient where the right table is small
and the left table is large.
Left and right tables with different key fields can be handled via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashAntiJoinView(left, right, lkey, rkey)
def hashantijoin(left, right, key=None, lkey=None, rkey=None):
"""
Alternative implementation of :func:`antijoin`, where the join is executed
by constructing an in-memory set for all keys found in the right hand table, then
iterating over rows from the left hand table.
May be faster and/or more resource efficient where the right table is small
and the left table is large.
.. versionadded:: 0.5
.. versionchanged:: 0.24
Added support for left and right tables with different key fields via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashAntiJoinView(left, right, lkey, rkey)
def hashrightjoin(left, right, key=None, lkey=None, rkey=None, missing=None,
cache=True, lprefix=None, rprefix=None):
"""Alternative implementation of :func:`petl.transform.joins.rightjoin`,
where the join is executed by constructing an in-memory lookup for the
left hand table, then iterating over rows from the right hand table.
May be faster and/or more resource efficient where the left table is small
and the right table is large.
By default data from right hand table is cached to improve performance
(only available when `key` is given).
Left and right tables with different key fields can be handled via the
`lkey` and `rkey` arguments.
"""
lkey, rkey = keys_from_args(left, right, key, lkey, rkey)
return HashRightJoinView(left, right, lkey, rkey, missing=missing,
cache=cache, lprefix=lprefix, rprefix=rprefix)
