Data commit

Task/Percolation-Site-percolation/Python/percolation-site-percolation.py

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+from random import random
+import string
+from pprint import pprint as pp
+
+M, N, t = 15, 15, 100
+
+cell2char = ' #' + string.ascii_letters
+NOT_VISITED = 1     # filled cell not walked
+
+class PercolatedException(Exception): pass
+
+def newgrid(p):
+    return [[int(random() < p) for m in range(M)] for n in range(N)] # cell
+
+def pgrid(cell, percolated=None):
+    for n in range(N):
+        print( '%i)  ' % (n % 10)
+               + ' '.join(cell2char[cell[n][m]] for m in range(M)))
+    if percolated:
+        where = percolated.args[0][0]
+        print('!)  ' + '  ' * where + cell2char[cell[n][where]])
+
+def check_from_top(cell):
+    n, walk_index = 0, 1
+    try:
+        for m in range(M):
+            if cell[n][m] == NOT_VISITED:
+                walk_index += 1
+                walk_maze(m, n, cell, walk_index)
+    except PercolatedException as ex:
+        return ex
+    return None
+
+
+def walk_maze(m, n, cell, indx):
+    # fill cell
+    cell[n][m] = indx
+    # down
+    if n < N - 1 and cell[n+1][m] == NOT_VISITED:
+        walk_maze(m, n+1, cell, indx)
+    # THE bottom
+    elif n == N - 1:
+        raise PercolatedException((m, indx))
+    # left
+    if m and cell[n][m - 1] == NOT_VISITED:
+        walk_maze(m-1, n, cell, indx)
+    # right
+    if m < M - 1 and cell[n][m + 1] == NOT_VISITED:
+        walk_maze(m+1, n, cell, indx)
+    # up
+    if n and cell[n-1][m] == NOT_VISITED:
+        walk_maze(m, n-1, cell, indx)
+
+if __name__ == '__main__':
+    sample_printed = False
+    pcount = {}
+    for p10 in range(11):
+        p = p10 / 10.0
+        pcount[p] = 0
+        for tries in range(t):
+            cell = newgrid(p)
+            percolated = check_from_top(cell)
+            if percolated:
+                pcount[p] += 1
+                if not sample_printed:
+                    print('\nSample percolating %i x %i, p = %5.2f grid\n' % (M, N, p))
+                    pgrid(cell, percolated)
+                    sample_printed = True
+    print('\n p: Fraction of %i tries that percolate through\n' % t )
+
+    pp({p:c/float(t) for p, c in pcount.items()})