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GeezerVison is showing github.com — ThinkPython2/code/invert_dict.py at master · AllenDowney/ThinkPython2 Expand file tree/ Copy pathinvert_dict.pyMore file actions 38 lines (26 loc) · 814 Bytes / Copy pathinvert_dict.pyFile metadata and controls38 lines (26 loc) · 814 Bytes 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 """This module contains a code example related to Think Python, 2nd Edition by Allen Downey https://greenteapress.com/wp/think-python-2e/ Copyright 2015 Allen Downey License: http://creativecommons.org/licenses/by/4.0/ """ from __future__ import print_function, division def invert_dict(d): """Inverts a dictionary, returning a map from val to a list of keys. If the mapping key->val appears in d, then in the new dictionary val maps to a list that includes key. d: dict Returns: dict """ inverse = {} for key in d: val = d[key] inverse.setdefault(val, []).append(key) return inverse if __name__ == '__main__': d = dict(a=1, b=2, c=3, z=1) inverse = invert_dict(d) for val in inverse: keys = inverse[val] print(val, keys) |
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