Data commit

Task/Zig-zag-matrix/Python/zig-zag-matrix-1.py

@@ -0,0 +1,22 @@
+def zigzag(n):
+    '''zigzag rows'''
+    def compare(xy):
+        x, y = xy
+        return (x + y, -y if (x + y) % 2 else y)
+    xs = range(n)
+    return {index: n for n, index in enumerate(sorted(
+        ((x, y) for x in xs for y in xs),
+        key=compare
+    ))}
+
+
+def printzz(myarray):
+    '''show zigzag rows as lines'''
+    n = int(len(myarray) ** 0.5 + 0.5)
+    xs = range(n)
+    print('\n'.join(
+        [''.join("%3i" % myarray[(x, y)] for x in xs) for y in xs]
+    ))
+
+
+printzz(zigzag(6))

Task/Zig-zag-matrix/Python/zig-zag-matrix-2.py

@@ -0,0 +1,33 @@
+# pylint: disable=invalid-name
+# pylint: disable=unused-argument
+"ZigZag iterator."
+import sys
+
+if sys.version_info[0] >= 3:
+    xrange = range
+
+def move(x, y, columns, rows):
+    "Tells us what to do next with x and y."
+    if y < (rows - 1):
+        return max(0, x-1), y+1
+    return x+1, y
+
+def zigzag(rows, columns):
+    "ZigZag iterator, yields indices."
+    x, y = 0, 0
+    size = rows * columns
+    for _ in xrange(size):
+        yield y, x
+        if (x + y) & 1:
+            x, y = move(x, y, columns, rows)
+        else:
+            y, x = move(y, x, rows, columns)
+
+# test code
+i, rows, cols = 0, 5, 5
+mat = [[0 for x in range(cols)] for y in range(rows)]
+for (y, x) in zigzag(rows, cols):
+    mat[y][x], i = i, i + 1
+
+from pprint import pprint
+pprint(mat)

Task/Zig-zag-matrix/Python/zig-zag-matrix-3.py

@@ -0,0 +1,5 @@
+[[0, 1, 5, 6, 14],
+ [2, 4, 7, 13, 15],
+ [3, 8, 12, 16, 21],
+ [9, 11, 17, 20, 22],
+ [10, 18, 19, 23, 24]]

Task/Zig-zag-matrix/Python/zig-zag-matrix-4.py

@@ -0,0 +1,16 @@
+COLS = 9
+def CX(x, ran):
+  while True:
+    x += 2 * next(ran)
+    yield x
+    x += 1
+    yield x
+ran = []
+d = -1
+for V in CX(1,iter(list(range(0,COLS,2)) + list(range(COLS-1-COLS%2,0,-2)))):
+  ran.append(iter(range(V, V+COLS*d, d)))
+  d *= -1
+for x in range(0,COLS):
+  for y in range(x, x+COLS):
+    print(repr(next(ran[y])).rjust(3), end = ' ')
+  print()

Task/Zig-zag-matrix/Python/zig-zag-matrix-5.py

@@ -0,0 +1,65 @@
+from __future__ import print_function
+
+import math
+
+
+def zigzag( dimension):
+    ''' generate the zigzag indexes for a square array
+        Exploiting the fact that an array is symmetrical around its
+        centre
+    '''
+    NUMBER_INDEXES = dimension ** 2
+    HALFWAY = NUMBER_INDEXES // 2
+    KERNEL_ODD = dimension & 1
+
+    xy = [0 for _ in range(NUMBER_INDEXES)]
+    # start at 0,0
+    ix = 0
+    iy = 0
+    # 'fake' that we are going up and right
+    direction = 1
+    # the first index is always 0, so start with the second
+    # until halfway
+    for i in range(1, HALFWAY + KERNEL_ODD):
+        if direction > 0:
+            # going up and right
+            if iy == 0:
+                # are at top
+                ix += 1
+                direction = -1
+            else:
+                ix += 1
+                iy -= 1
+        else:
+            # going down and left
+            if ix == 0:
+                # are at left
+                iy += 1
+                direction = 1
+            else:
+                ix -= 1
+                iy += 1
+        # update the index position
+        xy[iy * dimension + ix] = i
+
+    # have first half, but they are scattered over the list
+    # so find the zeros to replace
+    for i in range(1, NUMBER_INDEXES):
+        if xy[i] == 0 :
+            xy[i] = NUMBER_INDEXES - 1 - xy[NUMBER_INDEXES - 1 - i]
+
+    return xy
+
+
+def main(dim):
+    zz = zigzag(dim)
+    print( 'zigzag of {}:'.format(dim))
+    width = int(math.ceil(math.log10(dim**2)))
+    for j in range(dim):
+        for i in range(dim):
+            print('{:{width}}'.format(zz[j * dim + i], width=width), end=' ')
+        print()
+
+
+if __name__ == '__main__':
+    main(5)