evaluate#

named_arrays.numexpr.evaluate(ex, local_dict=None, global_dict=None, order='K', casting='same_kind', sanitize=None, optimization='aggressive', truediv='auto')#

A wrapper around numexpr.evaluate().

Evaluates a mathematical expression element-wise using the virtual machine.

Parameters:

  • ex (str) – a string forming an expression, like “2*a+3*b”. The values for “a” and “b” will by default be taken from the calling function’s frame (through use of sys._getframe()). Alternatively, they can be specified using the ‘local_dict’ or ‘global_dict’ arguments.

  • local_dict (None | dict) – A dictionary that replaces the local operands in current frame.

  • global_dict (None | dict) – A dictionary that replaces the global operands in current frame.

  • order ({'C', 'F', 'A', or 'K'}, optional) – Controls the iteration order for operands. ‘C’ means C order, ‘F’ means Fortran order, ‘A’ means ‘F’ order if all the arrays are Fortran contiguous, ‘C’ order otherwise, and ‘K’ means as close to the order the array elements appear in memory as possible. For efficient computations, typically ‘K’eep order (the default) is desired.

  • casting ({'no', 'equiv', 'safe', 'same_kind', 'unsafe'}, optional) –

    Controls what kind of data casting may occur when making a copy or buffering. Setting this to ‘unsafe’ is not recommended, as it can adversely affect accumulations.

    • ’no’ means the data types should not be cast at all.

    • ’equiv’ means only byte-order changes are allowed.

    • ’safe’ means only casts which can preserve values are allowed.

    • ’same_kind’ means only safe casts or casts within a kind, like float64 to float32, are allowed.

    • ’unsafe’ means any data conversions may be done.

  • sanitize (bool) –

    validate (and by extension evaluate) call eval(ex), which is potentially dangerous on non-sanitized inputs. As such, NumExpr by default performs simple sanitization, banning the characters ‘:;[’, the dunder ‘__[w+]__’, and attribute access to all but ‘.real’ and ‘.imag’.

    Using None defaults to True unless the environment variable NUMEXPR_SANITIZE=0 is set, in which case the default is False. Nominally this can be set via os.environ before import numexpr.

  • optimization (Literal['none', 'moderate', 'aggressive']) – The optimization level of the compiler

  • truediv (bool | Literal['auto']) – Whether to use integer or floating-point division.