array.pop / push?

Programming Questions

jorrebor

in Programming Questions • 2 years ago

Does processing not provide a array.pop() / push() function?

i want to store values coming from the motion sensor of my phone in an array and draw a graph of points based on this array.

When the length of the array reaches a certain value (800 in my case) i want to shift all values 1 position to the left and add a new value at position 799.

A new graph should be drawn based on this.

To conclude: if the graph reaches the end of the square the graph should move to the left. For some reason this doesnt happen with my code... i'm left with some flickering stars :(

import peasy.*;
import shapes3d.utils.*;
import shapes3d.animation.*;
import shapes3d.*;
import controlP5.*;
import rwmidi.*;
import processing.opengl.*;
import oscP5.*;
import netP5.*;
NetAddress myRemoteLocation;
OscP5 oscP5;
Graph myGraph;
//global rotation parameters
float rx, ry, rz;
void setup() {
smooth();
size(900, 500, OPENGL);
background(0);
lights();
oscP5 = new OscP5(this, 12000);
myRemoteLocation = new NetAddress("192.168.1.17", 12000);
myGraph = new Graph(100,100,800,200,-10,10);
}
void draw() {
rx = random(-10,10);
myGraph.storePoints();
myGraph.display();
if (frameCount > 799){
myGraph.movePoints();
}
}
class Graph {
//fields
int xPos, yPos, wd, ht, rgL, rgH, c;
PVector[] pointArray = new PVector[800];
//constructor
Graph(int _xPos, int _yPos, int _wd, int _ht, int _rgL, int _rgH ) { //xpos, ypos, width, height, min_point, max_point
xPos = _xPos;
yPos = _yPos;
wd = _wd;
ht = _ht;
rgL = _rgL;
rgH = _rgH;
for (int i = 0; i < pointArray.length; i++) {
pointArray[i] = new PVector();
}
}
//methods
void display () {
for (int i = 0; i < pointArray.length; i++) {
noFill();
rect(xPos, yPos, wd, ht);
stroke(255);
point(xPos + pointArray[i].x, yPos + pointArray[i].y);
}
}
void movePoints () {
for (int i = 1; i < pointArray.length; i++) {
pointArray[i-1] = pointArray[i];
println("i:" + i);
}
}
//get rotation value and store as y-component of vector
void storePoints () {
if (frameCount < 800) {
pointArray[c].y = map(rx, -10, 10, 0, ht);
pointArray[c].x = frameCount;
}
else {
pointArray[798].y = map(rx, -10, 10, 0, ht);
pointArray[798].x = xPos + wd;
}
}
}

Thanks!

Replies(4)

thomas.di..

depeding on the number of values you are going to add, and also the performance needs, there are some different solutions.

one would be, using an arraylist, and adding dynamically values. instead of shifting the array to the left, you could just shift your startindex to the right.

another selfmade thing would be the following. it can be slower, because the array is getting copied, everytime, you are adding a number at the last position

void setup() {
int my_array[] = new int[10];
//initialize some values
for (int i = 0; i < my_array.length; i++) {
my_array[i] = i;
}
printArray(my_array);
shiftAndAdd(my_array, 10);
printArray(my_array);
shiftAndAdd(my_array, 999);
printArray(my_array);
}
// shift all the values to the left, and set the new value at the end
void shiftAndAdd(int a[], int val){
int a_length = a.length;
System.arraycopy(a, 1, a, 0, a_length-1);
a[a_length-1] = val;
}
// function to print array values in a row
void printArray(int a[]) {
for (int i = 0; i < a.length; i++) {
print(a[i]);
if ( i < a.length-1 )
print(", ");
}
println("\n----");
}

jorrebor

Re: Re: array.pop / push?

2 years ago

will try both!

thanks

didnt know about the system.arraycopy function though. Is it in the documentation of processing?

jorrebor

Re: Re: array.pop / push?

2 years ago

your solution works partially (for me; while it works fine for shifting arrays :):

please have a look at http://forum.processing.org/topic/problem-with-animation-of-graph

thanks!

PhiLho

Re: array.pop / push?

2 years ago

Processing offers arrayCopy which just calls the Java' System.arraycopy one...

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