how would you do it? random order, every number only once

Programming Questions

clankill3r

how would you do it? random order, every number only once

in Programming Questions • 2 years ago

I got what i want but for the purpose of learning i was wondering for different methods.

Mine does fine on a short document but if i wanted the lines of a book back in random order then it would take forever.

PrintWriter output;// = createWriter("output.txt");
int[] openList;
void setup() {
output = createWriter("output2.txt");
String[] lines = loadStrings("lines.txt");
openList = new int[lines.length];
// fill open list with a id for every line
for(int i=0; i<lines.length; i++){
openList[i] = i;
}
int count = 0;
while(count < lines.length){
int number = int(random(0, lines.length));
if(openList[number] != -1){
output.println(lines[number]);
openList[number] = -1;
count ++;
}
}
output.flush();
output.close();
exit();
}

Replies(3)

cedrickie..

Re: how would you do it? random order, every number only once

2 years ago

take a look at my example with a similar problem.
filling the screen randomly, but only pick the pixels that were not taken yet.
what i do is fill an array with all elements you need, and then shuffle the array. after you shuffled it, you can simply loop through it, and never get the same element twice.

Integer[] pixelArray;
void setup(){
  size(100,100);
  pixelArray = new Integer[width*height];
  for(int i = 0; i<width*height;i++){
    pixelArray[i] = i;
frameRate(1000);
  }
  Collections.shuffle(Arrays.asList(pixelArray));
  background(0);
}
int i;
color cc = color(random(255),random(255),random(255));

void draw(){
  loadPixels();
 
  pixels[pixelArray[i]] = cc;
  i++;
  updatePixels();

  if(i==width*height){
    i=0;
    cc = color(random(255),random(255),random(255));
  }
}

alphachap

Re: how would you do it? random order, every number only once

2 years ago

I modified cedrickiefer's code to draw the pixels with color going from black to white.

I was just curious to see if some pattern would show up.

It's quite slow. Of course there's a lot of pixels, but still it's slower than I was expecting.

int i;
Integer[] pixelArray;
int nPixels;
void setup() {
size(100,100);
background(230,250,230);
nPixels=width*height;
pixelArray = new Integer[nPixels];
for(int i = 0; i<nPixels;i++) {
pixelArray[i] = i;
}
Collections.shuffle(Arrays.asList(pixelArray));
}
void draw() {
float iRatio, i255up, r, g, b;
loadPixels();
//coloring black to white for i=0 to max
iRatio=i/float(nPixels);
i255up=iRatio*255;
r=i255up;
g=i255up;
b=i255up;
pixels[pixelArray[i]] = color(r,g,b);
i++;
updatePixels();
if (i00==0) println(i);
if (i==nPixels) {
    noLoop();
}
}

clankill3r

Re: how would you do it? random order, every number only once

2 years ago

cool thanks,

i didn't know the shuffle function, that makes stuff a lot easier.

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