name : print_coercion_tables.py #!/usr/bin/env python3 """Prints type-coercion tables for the built-in NumPy types """ import numpy as np from collections import namedtuple # Generic object that can be added, but doesn't do anything else class GenericObject: def __init__(self, v): self.v = v def __add__(self, other): return self def __radd__(self, other): return self dtype = np.dtype('O') def print_cancast_table(ntypes): print('X', end=' ') for char in ntypes: print(char, end=' ') print() for row in ntypes: print(row, end=' ') for col in ntypes: if np.can_cast(row, col, "equiv"): cast = "#" elif np.can_cast(row, col, "safe"): cast = "=" elif np.can_cast(row, col, "same_kind"): cast = "~" elif np.can_cast(row, col, "unsafe"): cast = "." else: cast = " " print(cast, end=' ') print() def print_coercion_table(ntypes, inputfirstvalue, inputsecondvalue, firstarray, use_promote_types=False): print('+', end=' ') for char in ntypes: print(char, end=' ') print() for row in ntypes: if row == 'O': rowtype = GenericObject else: rowtype = np.obj2sctype(row) print(row, end=' ') for col in ntypes: if col == 'O': coltype = GenericObject else: coltype = np.obj2sctype(col) try: if firstarray: rowvalue = np.array([rowtype(inputfirstvalue)], dtype=rowtype) else: rowvalue = rowtype(inputfirstvalue) colvalue = coltype(inputsecondvalue) if use_promote_types: char = np.promote_types(rowvalue.dtype, colvalue.dtype).char else: value = np.add(rowvalue, colvalue) if isinstance(value, np.ndarray): char = value.dtype.char else: char = np.dtype(type(value)).char except ValueError: char = '!' except OverflowError: char = '@' except TypeError: char = '#' print(char, end=' ') print() def print_new_cast_table(*, can_cast=True, legacy=False, flags=False): """Prints new casts, the values given are default "can-cast" values, not actual ones. """ from numpy.core._multiarray_tests import get_all_cast_information cast_table = { -1: " ", 0: "#", # No cast (classify as equivalent here) 1: "#", # equivalent casting 2: "=", # safe casting 3: "~", # same-kind casting 4: ".", # unsafe casting } flags_table = { 0 : "▗", 7: "█", 1: "▚", 2: "▐", 4: "▄", 3: "▜", 5: "▙", 6: "▟", } cast_info = namedtuple("cast_info", ["can_cast", "legacy", "flags"]) no_cast_info = cast_info(" ", " ", " ") casts = get_all_cast_information() table = {} dtypes = set() for cast in casts: dtypes.add(cast["from"]) dtypes.add(cast["to"]) if cast["from"] not in table: table[cast["from"]] = {} to_dict = table[cast["from"]] can_cast = cast_table[cast["casting"]] legacy = "L" if cast["legacy"] else "." flags = 0 if cast["requires_pyapi"]: flags |= 1 if cast["supports_unaligned"]: flags |= 2 if cast["no_floatingpoint_errors"]: flags |= 4 flags = flags_table[flags] to_dict[cast["to"]] = cast_info(can_cast=can_cast, legacy=legacy, flags=flags) # The np.dtype(x.type) is a bit strange, because dtype classes do # not expose much yet. types = np.typecodes["All"] def sorter(x): # This is a bit weird hack, to get a table as close as possible to # the one printing all typecodes (but expecting user-dtypes). dtype = np.dtype(x.type) try: indx = types.index(dtype.char) except ValueError: indx = np.inf return (indx, dtype.char) dtypes = sorted(dtypes, key=sorter) def print_table(field="can_cast"): print('X', end=' ') for dt in dtypes: print(np.dtype(dt.type).char, end=' ') print() for from_dt in dtypes: print(np.dtype(from_dt.type).char, end=' ') row = table.get(from_dt, {}) for to_dt in dtypes: print(getattr(row.get(to_dt, no_cast_info), field), end=' ') print() if can_cast: # Print the actual table: print() print("Casting: # is equivalent, = is safe, ~ is same-kind, and . is unsafe") print() print_table("can_cast") if legacy: print() print("L denotes a legacy cast . a non-legacy one.") print() print_table("legacy") if flags: print() print(f"{flags_table[0]}: no flags, {flags_table[1]}: PyAPI, " f"{flags_table[2]}: supports unaligned, {flags_table[4]}: no-float-errors") print() print_table("flags") if __name__ == '__main__': print("can cast") print_cancast_table(np.typecodes['All']) print() print("In these tables, ValueError is '!', OverflowError is '@', TypeError is '#'") print() print("scalar + scalar") print_coercion_table(np.typecodes['All'], 0, 0, False) print() print("scalar + neg scalar") print_coercion_table(np.typecodes['All'], 0, -1, False) print() print("array + scalar") print_coercion_table(np.typecodes['All'], 0, 0, True) print() print("array + neg scalar") print_coercion_table(np.typecodes['All'], 0, -1, True) print() print("promote_types") print_coercion_table(np.typecodes['All'], 0, 0, False, True) print("New casting type promotion:") print_new_cast_table(can_cast=True, legacy=True, flags=True)