How to handle mypy implementation errors?

[algobytewise]

Many of the current errors when running the command mypy . are implementation errors of the following form: scheduling\shortest_job_first.py:8: error: Cannot find implementation or library stub for module named 'pandas'. These errors can be fixed by adding the comment # type: ignore at the end of the line, thereby telling mypy to ignore them, for example import pandas as pd # type: ignore. But all these errors can be silenced by running the command mypy . --ignore-missing-imports, avoiding the need to fix them one by one. So the question is: should these errors be fixed for each file or can they be ignored since the check to be implemented will silence them anyways? Without the ignore-parameter, we have: Found 586 errors in 189 files. With it, we have: Found 477 errors in 132 files.

[algobytewise]

The mypy documentation of this issue can be found here: https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

[algobytewise]

@cclauss just pointed out to me that the automatic checks already include the ignore-missing-imports parameter, so the implementation errors don't need to be fixed. See https://github.com/TheAlgorithms/Python/blob/master/.pre-commit-config.yaml#L33

[cclauss]

Those tests are commented out so it would be awesome if we could put the fixes in place so that we can automatically run mypy -ignore-missing-imports . on every pull request.

[cclauss]

% mypy --ignore-missing-imports . > files.txt
% python3

>>> with open("files.txt") as in_file:
...     print("\n* [ ] ".join(sorted(set(line.split(":")[0] for line in in_file))))
...

• ciphers/cryptomath_module.py
• ciphers/decrypt_caesar_with_chi_squared.py
• ciphers/diffie.py
• ciphers/diffie_hellman.py
• ciphers/elgamal_key_generator.py
• ciphers/enigma_machine2.py
• ciphers/hill_cipher.py
• ciphers/mixed_keyword_cypher.py
• ciphers/onepad_cipher.py
• ciphers/playfair_cipher.py
• ciphers/porta_cipher.py
• ciphers/rail_fence_cipher.py
• ciphers/rsa_cipher.py
• ciphers/rsa_factorization.py
• ciphers/shuffled_shift_cipher.py
• ciphers/trafid_cipher.py
• ciphers/xor_cipher.py
• compression/lempel_ziv.py
• conversions/decimal_to_binary.py
• conversions/decimal_to_octal.py
• conversions/prefix_conversions.py
• data_structures/binary_tree/binary_search_tree.py
• data_structures/binary_tree/lowest_common_ancestor.py
• data_structures/binary_tree/merge_two_binary_trees.py
• data_structures/binary_tree/non_recursive_segment_tree.py
• data_structures/binary_tree/red_black_tree.py
• data_structures/heap/randomized_heap.py
• data_structures/heap/skew_heap.py
• data_structures/linked_list/init.py
• data_structures/linked_list/circular_linked_list.py
• data_structures/linked_list/has_loop.py
• data_structures/linked_list/middle_element_of_linked_list.py
• data_structures/linked_list/skip_list.py
• data_structures/queue/linked_queue.py
• data_structures/stacks/evaluate_postfix_notations.py
• data_structures/stacks/linked_stack.py
• data_structures/stacks/next_greater_element.py
• data_structures/stacks/stack.py
• data_structures/trie/trie.py
• divide_and_conquer/max_difference_pair.py
• divide_and_conquer/strassen_matrix_multiplication.py
• dynamic_programming/fractional_knapsack_2.py
• dynamic_programming/knapsack.py
• dynamic_programming/longest_increasing_subsequence.py
• electronics/electric_power.py
• electronics/ohms_law.py
• file_transfer/receive_file.py
• file_transfer/send_file.py
• graphs/basic_graphs.py
• graphs/bellman_ford.py
• graphs/bfs_shortest_path.py
• graphs/bfs_zero_one_shortest_path.py
• graphs/bidirectional_a_star.py
• graphs/bidirectional_breadth_first_search.py
• graphs/breadth_first_search.py
• graphs/breadth_first_search_shortest_path.py
• graphs/depth_first_search.py
• graphs/even_tree.py
• graphs/frequent_pattern_graph_miner.py
• graphs/gale_shapley_bigraph.py
• graphs/graph_list.py
• graphs/greedy_best_first.py
• graphs/minimum_spanning_tree_kruskal.py
• graphs/minimum_spanning_tree_kruskal2.py
• graphs/minimum_spanning_tree_prims2.py
• graphs/multi_heuristic_astar.py
• graphs/scc_kosaraju.py
• graphs/strongly_connected_components.py
• hashes/adler32.py
• hashes/chaos_machine.py
• hashes/enigma_machine.py
• hashes/sdbm.py
• linear_algebra/src/polynom_for_points.py
• linear_algebra/src/power_iteration.py
• machine_learning/forecasting/run.py
• machine_learning/word_frequency_functions.py
• maths/series/geometric_series.py
• maths/series/harmonic_series.py
• maths/series/p_series.py
• matrix/matrix_operation.py
• neural_network/perceptron.py
• other/davis–putnam–logemann–loveland.py
• other/graham_scan.py
• other/least_recently_used.py
• other/lfu_cache.py
• other/lru_cache.py
• other/markov_chain.py
• other/scoring_algorithm.py
• other/triplet_sum.py
• other/two_sum.py
• other/word_patterns.py
• project_euler/problem_003/sol1.py
• project_euler/problem_003/sol3.py
• project_euler/problem_007/sol2.py
• project_euler/problem_008/sol2.py
• project_euler/problem_009/sol1.py
• project_euler/problem_014/sol1.py
• project_euler/problem_025/sol2.py
• project_euler/problem_026/sol1.py
• project_euler/problem_037/sol1.py
• project_euler/problem_044/sol1.py
• project_euler/problem_046/sol1.py
• project_euler/problem_051/sol1.py
• project_euler/problem_074/sol2.py
• project_euler/problem_080/sol1.py
• project_euler/problem_099/sol1.py
• project_euler/problem_101/sol1.py
• project_euler/problem_188/sol1.py
• project_euler/problem_191/sol1.py
• project_euler/problem_207/sol1.py
• project_euler/problem_551/sol1.py
• quantum/ripple_adder_classic.py
• scripts/validate_filenames.py
• scripts/validate_solutions.py
• searches/simulated_annealing.py
• searches/ternary_search.py
• strings/aho_corasick.py
• strings/can_string_be_rearranged_as_palindrome.py
• strings/levenshtein_distance.py
• strings/manacher.py
• strings/min_cost_string_conversion.py
• strings/word_occurrence.py
• traversals/binary_tree_traversals.py
• web_programming/currency_converter.py
• web_programming/emails_from_url.py

[cclauss]

So... We can successfully run

% mypy --ignore-missing-imports arithmetic_analysis backtracking bit_manipulation blockchain boolean_algebra cellular_automata computer_vision digital_image_processing fuzzy_logic genetic_algorithm geodesy knapsack networking_flow scheduling sorts
Success: no issues found in 138 source files

[cclauss]

#4274 works better than #4272

[cclauss]

Let's focus the mypy discussions on #4052