public static int[] zigzagify(int[] array, int xmax, int ymax) {
int[] zz = new int[array.length]; //zigzag array
if (array.length != xmax * ymax) {
throw new IllegalArgumentException();
}
int ai = 0; //original array index
int zzi = 0; //zigzag array index
int x = 0; //x position
int y = 0; //y position
zz[zzi] = array[ai];
while (y * xmax + x < xmax * ymax - 1) {
if(x<xmax-1) x++;
else y++;
zzi++;
ai = y * xmax + x;
System.out.println("x "+x+", y "+y+", zzi "+zzi+", ai "+ai);
zz[zzi] = array[ai];
while (x > 0 && y < ymax-1) {
x--;
y++;
zzi++;
ai = y * xmax + x;
System.out.println("x "+x+", y "+y+", zzi "+zzi+", ai "+ai);
zz[zzi] = array[ai];
}
if(y<ymax-1) y++;
else x++;
zzi++;
ai = y * xmax + x;
System.out.println("x "+x+", y "+y+", zzi "+zzi+", ai "+ai);
zz[zzi] = array[ai];
while (y > 0 && x < xmax-1) {
y--;
x++;
zzi++;
ai = y * xmax + x;
System.out.println("x "+x+", y "+y+", zzi "+zzi+", ai "+ai);
zz[zzi] = array[ai];
}
}
return zz;
}
Refactorings
No refactoring yet !
Kaloyan
August 20, 2008, August 20, 2008 08:28, permalink
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IMHO the code cannot get much more readable that what you posted. You could try to gather the two inner loops together, since they are completely symmetrical. I'm posting an example to give you an idea
public static int[] zigzagify(int[] array, int xmax, int ymax) {
int[] zz = new int[array.length]; //zigzag array
if (array.length != xmax * ymax) {
throw new IllegalArgumentException();
}
int x = 0;
int y = 1;
int step = 1;
int zzi = 0;
zz[zzi++] = array[0];
System.out.println(0 + " " + 0);
while (xmax-1 != x || ymax-1 != y) {
do {
System.out.println(x + " " + y);
zz[zzi++] = array[y * xmax + x];
x += step;
y -= step;
} while ( (x > 0) && (x < xmax -1) && (y > 0) && (y < ymax -1));
step = -step;
System.out.println(x + " " + y);
zz[zzi++] = array[y * xmax + x];
if (y == 0 || y == ymax - 1) {
x++;
} else {
y++;
}
}
System.out.println(x + " " + y);
zz[zz.length - 1] = array[array.length - 1];
return zz;
}
Kaloyan
August 20, 2008, August 20, 2008 11:29, permalink
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There's a bug at line 25, fix it with
if ((y == 0 && x < xmax -1) || y == ymax - 1) {
Kaloyan
August 20, 2008, August 20, 2008 12:13, permalink
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okay, I think I came up with something better, how about generating the indexes of the next element iteratively as you go over the source array ?
public static int[] zigzag2(int[] array, int xmax, int ymax) {
int[] zz = new int[array.length];
int x = 1;
int y = 1;
for(int t = 0; t < array.length; t++){
zz[t] = array[(y - 1) * xmax + (x - 1)];
System.out.println((x-1) + " " + (y - 1));
if((x + y) % 2 == 0) {
// Even stripes
if (y < ymax) {
y++;
} else {
x+= 2;
}
if (x > 1) {
x--;
}
} else {
// Odd stripes
if (x < xmax) {
x++;
} else {
y+= 2;
}
if (y > 1) {
y--;
}
}
}
return zz;
}
mcintyre321
March 28, 2009, March 28, 2009 23:36, permalink
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hi there, I thought you might find my snippet interesting! http://refactormycode.com/codes/806-algorithm-for-zig-zagging-over-potentially-infinite-sets :)
This is the code that is supposed to turn array in normal order into array with zig-zag order (like this: http://en.wikipedia.org/wiki/Image:JPEG_ZigZag.svg). Normally the input and output array would be 2d array, but because of how the output array is used, it is only simple array, therefore xmax and ymax are used to specify how the imaginary 2d array should look like.