def newfunc(exprnode, indexedcols):
result = getidxcmp(exprnode, indexedcols)
if result[0] is not None:
try:
typeCompileAst(expressionToAST(exprnode))
except NotImplementedError, nie:
# Try to make this Numexpr error less cryptic.
raise _unsupported_operation_error(nie)
def newfunc(exprnode, indexedcols):
result = getidxcmp(exprnode, indexedcols)
if result[0] is not None:
try:
typeCompileAst(expressionToAST(exprnode))
except NotImplementedError, nie:
# Try to make this Numexpr error less cryptic.
raise _unsupported_operation_error(nie)
def compile_condition(condition, typemap, indexedcols, copycols):
"""
Compile a condition and extract usable index conditions.
Looks for variable-constant comparisons in the `condition` string
involving the indexed columns whose variable names appear in
`indexedcols`. The part of `condition` having usable indexes is
returned as a compiled condition in a `CompiledCondition` container.
Expressions such as '0 < c1 <= 1' do not work as expected. The
Numexpr types of *all* variables must be given in the `typemap`
mapping. The ``function`` of the resulting `CompiledCondition`
instance is a Numexpr function object, and the ``parameters`` list
indicates the order of its parameters.
For columns whose variable names appear in `copycols`, an
additional copy operation is inserted whenever the column is
referenced. This seems to accelerate access to unaligned,
*unidimensional* arrays up to 2x (multidimensional arrays still
need to be copied by `call_on_recarr()`.).
"""
# Get the expression tree and extract index conditions.
expr = stringToExpression(condition, typemap, {})
if expr.astKind != 'bool':
raise TypeError( "condition ``%s`` does not have a boolean type"
% condition )
idxexprs = _get_idx_expr(expr, indexedcols)
# Post-process the answer
if type(idxexprs) == list:
# Simple expression
strexpr = ['e0']
else:
# Complex expression
idxexprs, strexpr = idxexprs
# Get rid of the unneccessary list wrapper for strexpr
strexpr = strexpr[0]
# Get the variable names used in the condition.
# At the same time, build its signature.
varnames = _get_variable_names(expr)
signature = [(var, typemap[var]) for var in varnames]
try:
# See the comments in `numexpr.evaluate()` for the
# reasons of inserting copy operators for unaligned,
# *unidimensional* arrays.
func = NumExpr(expr, signature, copy_args=copycols)
except NotImplementedError, nie:
# Try to make this Numexpr error less cryptic.
raise _unsupported_operation_error(nie)
