Add Flake8 comprehensions to pre-commit (TheAlgorithms#7235)

* ci(pre-commit): Add ``flake8-comprehensions`` to ``pre-commit`` (TheAlgorithms#7233)

* refactor: Fix ``flake8-comprehensions`` errors

* fix: Replace `map` with generator (TheAlgorithms#7233)

* fix: Cast `range` objects to `list`

.pre-commit-config.yaml

@@ -39,6 +39,7 @@ repos:
         additional_dependencies:
           - flake8-bugbear
           - flake8-builtins
+          - flake8-comprehensions
           - pep8-naming
 
   - repo: https://github.com/pre-commit/mirrors-mypy

ciphers/onepad_cipher.py

@@ -22,7 +22,7 @@ def decrypt(cipher: list[int], key: list[int]) -> str:
         for i in range(len(key)):
             p = int((cipher[i] - (key[i]) ** 2) / key[i])
             plain.append(chr(p))
-        return "".join([i for i in plain])
+        return "".join(plain)
 
 
 if __name__ == "__main__":

ciphers/rail_fence_cipher.py

@@ -72,7 +72,7 @@ def decrypt(input_string: str, key: int) -> str:
     counter = 0
     for row in temp_grid:  # fills in the characters
         splice = input_string[counter : counter + len(row)]
-        grid.append([character for character in splice])
+        grid.append(list(splice))
         counter += len(row)
 
     output_string = ""  # reads as zigzag

data_structures/hashing/hash_table.py

@@ -34,7 +34,7 @@ def hash_function(self, key):
     def _step_by_step(self, step_ord):
 
         print(f"step {step_ord}")
-        print([i for i in range(len(self.values))])
+        print(list(range(len(self.values))))
         print(self.values)
 
     def bulk_insert(self, values):

data_structures/linked_list/merge_two_lists.py

@@ -19,7 +19,7 @@ class Node:
 class SortedLinkedList:
     def __init__(self, ints: Iterable[int]) -> None:
         self.head: Node | None = None
-        for i in reversed(sorted(ints)):
+        for i in sorted(ints, reverse=True):
             self.head = Node(i, self.head)
 
     def __iter__(self) -> Iterator[int]:

dynamic_programming/fractional_knapsack.py

@@ -8,7 +8,7 @@ def frac_knapsack(vl, wt, w, n):
     240.0
     """
 
-    r = list(sorted(zip(vl, wt), key=lambda x: x[0] / x[1], reverse=True))
+    r = sorted(zip(vl, wt), key=lambda x: x[0] / x[1], reverse=True)
     vl, wt = [i[0] for i in r], [i[1] for i in r]
     acc = list(accumulate(wt))
     k = bisect(acc, w)

graphs/bellman_ford.py

@@ -58,7 +58,7 @@ def bellman_ford(
     V = int(input("Enter number of vertices: ").strip())
     E = int(input("Enter number of edges: ").strip())
 
-    graph: list[dict[str, int]] = [dict() for j in range(E)]
+    graph: list[dict[str, int]] = [{} for _ in range(E)]
 
     for i in range(E):
         print("Edge ", i + 1)

graphs/frequent_pattern_graph_miner.py

@@ -155,12 +155,12 @@ def construct_graph(cluster, nodes):
     cluster[max(cluster.keys()) + 1] = "Header"
     graph = {}
     for i in x:
-        if tuple(["Header"]) in graph:
-            graph[tuple(["Header"])].append(x[i])
+        if (["Header"],) in graph:
+            graph[(["Header"],)].append(x[i])
         else:
-            graph[tuple(["Header"])] = [x[i]]
+            graph[(["Header"],)] = [x[i]]
     for i in x:
-        graph[tuple(x[i])] = [["Header"]]
+        graph[(x[i],)] = [["Header"]]
     i = 1
     while i < max(cluster) - 1:
         create_edge(nodes, graph, cluster, i)
@@ -186,7 +186,7 @@ def find_freq_subgraph_given_support(s, cluster, graph):
     """
     k = int(s / 100 * (len(cluster) - 1))
     for i in cluster[k].keys():
-        my_dfs(graph, tuple(cluster[k][i]), tuple(["Header"]))
+        my_dfs(graph, tuple(cluster[k][i]), (["Header"],))
 
 
 def freq_subgraphs_edge_list(paths):

hashes/enigma_machine.py

@@ -1,8 +1,8 @@
 alphabets = [chr(i) for i in range(32, 126)]
-gear_one = [i for i in range(len(alphabets))]
-gear_two = [i for i in range(len(alphabets))]
-gear_three = [i for i in range(len(alphabets))]
-reflector = [i for i in reversed(range(len(alphabets)))]
+gear_one = list(range(len(alphabets)))
+gear_two = list(range(len(alphabets)))
+gear_three = list(range(len(alphabets)))
+reflector = list(reversed(range(len(alphabets))))
 code = []
 gear_one_pos = gear_two_pos = gear_three_pos = 0
 

maths/primelib.py

@@ -89,7 +89,7 @@ def sieve_er(n):
     assert isinstance(n, int) and (n > 2), "'N' must been an int and > 2"
 
     # beginList: contains all natural numbers from 2 up to N
-    begin_list = [x for x in range(2, n + 1)]
+    begin_list = list(range(2, n + 1))
 
     ans = []  # this list will be returns.
 

matrix/spiral_print.py

@@ -9,7 +9,7 @@
 
 def check_matrix(matrix: list[list[int]]) -> bool:
     # must be
-    matrix = list(list(row) for row in matrix)
+    matrix = [list(row) for row in matrix]
     if matrix and isinstance(matrix, list):
         if isinstance(matrix[0], list):
             prev_len = 0
@@ -44,7 +44,7 @@ def spiral_print_clockwise(a: list[list[int]]) -> None:
     7
     """
     if check_matrix(a) and len(a) > 0:
-        a = list(list(row) for row in a)
+        a = [list(row) for row in a]
         mat_row = len(a)
         if isinstance(a[0], list):
             mat_col = len(a[0])

other/davisb_putnamb_logemannb_loveland.py

@@ -317,7 +317,7 @@ def dpll_algorithm(
     if p:
         tmp_model = model
         tmp_model[p] = value
-        tmp_symbols = [i for i in symbols]
+        tmp_symbols = list(symbols)
         if p in tmp_symbols:
             tmp_symbols.remove(p)
         return dpll_algorithm(clauses, tmp_symbols, tmp_model)
@@ -329,7 +329,7 @@ def dpll_algorithm(
     if p:
         tmp_model = model
         tmp_model[p] = value
-        tmp_symbols = [i for i in symbols]
+        tmp_symbols = list(symbols)
         if p in tmp_symbols:
             tmp_symbols.remove(p)
         return dpll_algorithm(clauses, tmp_symbols, tmp_model)

project_euler/problem_042/solution42.py

@@ -33,11 +33,11 @@ def solution():
     with open(words_file_path) as f:
         words = f.readline()
 
-    words = list(map(lambda word: word.strip('"'), words.strip("\r\n").split(",")))
+    words = [word.strip('"') for word in words.strip("\r\n").split(",")]
     words = list(
         filter(
             lambda word: word in TRIANGULAR_NUMBERS,
-            map(lambda word: sum(map(lambda x: ord(x) - 64, word)), words),
+            (sum(ord(x) - 64 for x in word) for word in words),
         )
     )
     return len(words)

project_euler/problem_052/sol1.py

@@ -21,12 +21,12 @@ def solution():
 
     while True:
         if (
-            sorted(list(str(i)))
-            == sorted(list(str(2 * i)))
-            == sorted(list(str(3 * i)))
-            == sorted(list(str(4 * i)))
-            == sorted(list(str(5 * i)))
-            == sorted(list(str(6 * i)))
+            sorted(str(i))
+            == sorted(str(2 * i))
+            == sorted(str(3 * i))
+            == sorted(str(4 * i))
+            == sorted(str(5 * i))
+            == sorted(str(6 * i))
         ):
             return i
 

project_euler/problem_062/sol1.py

@@ -55,7 +55,7 @@ def get_digits(num: int) -> str:
     >>> get_digits(123)
     '0166788'
     """
-    return "".join(sorted(list(str(num**3))))
+    return "".join(sorted(str(num**3)))
 
 
 if __name__ == "__main__":

project_euler/problem_067/sol1.py

@@ -28,8 +28,8 @@ def solution():
     with open(triangle) as f:
         triangle = f.readlines()
 
-    a = map(lambda x: x.rstrip("\r\n").split(" "), triangle)
-    a = list(map(lambda x: list(map(int, x)), a))
+    a = (x.rstrip("\r\n").split(" ") for x in triangle)
+    a = [list(map(int, x)) for x in a]
 
     for i in range(1, len(a)):
         for j in range(len(a[i])):

project_euler/problem_109/sol1.py

@@ -65,7 +65,7 @@ def solution(limit: int = 100) -> int:
     >>> solution(50)
     12577
     """
-    singles: list[int] = [x for x in range(1, 21)] + [25]
+    singles: list[int] = list(range(1, 21)) + [25]
     doubles: list[int] = [2 * x for x in range(1, 21)] + [50]
     triples: list[int] = [3 * x for x in range(1, 21)]
     all_values: list[int] = singles + doubles + triples + [0]

project_euler/problem_551/sol1.py

@@ -13,7 +13,7 @@
 """
 
 
-ks = [k for k in range(2, 20 + 1)]
+ks = range(2, 20 + 1)
 base = [10**k for k in range(ks[-1] + 1)]
 memo: dict[int, dict[int, list[list[int]]]] = {}
 

sorts/radix_sort.py

@@ -24,7 +24,7 @@ def radix_sort(list_of_ints: list[int]) -> list[int]:
     max_digit = max(list_of_ints)
     while placement <= max_digit:
         # declare and initialize empty buckets
-        buckets: list[list] = [list() for _ in range(RADIX)]
+        buckets: list[list] = [[] for _ in range(RADIX)]
         # split list_of_ints between the buckets
         for i in list_of_ints:
             tmp = int((i / placement) % RADIX)

strings/aho_corasick.py

@@ -70,9 +70,7 @@ def search_in(self, string: str) -> dict[str, list[int]]:
         >>> A.search_in("whatever, err ... , wherever")
         {'what': [0], 'hat': [1], 'ver': [5, 25], 'er': [6, 10, 22, 26]}
         """
-        result: dict = (
-            dict()
-        )  # returns a dict with keywords and list of its occurrences
+        result: dict = {}  # returns a dict with keywords and list of its occurrences
         current_state = 0
         for i in range(len(string)):
             while (