Loop through XML data efficiently

Programming Questions

kpowe11

Loop through XML data efficiently

in Programming Questions • 2 years ago

I'm trying to load data from an XML file once and then again after changing the child to create a heat map. Is there a way to do this without having to create a loop for each for new child? In this case I want a row for each month of unemployment data for every state. Thanks.

void setup() {
size(600, 600, P3D);
background(255);
smooth();
loadMonth();
loadMonth2();
}
void draw() {
}
void loadMonth() {
pushMatrix();
for (int i = 0; i < 50; i++) {
XMLElement xml = new XMLElement(this, "unemployment.xml");
XMLElement stateData = xml.getChild(i);
XMLElement monthlyData = stateData.getChild(1);
String monthlyNumber = monthlyData.getContent();
float monthlyFloat = float(monthlyNumber);
float colorMap = map(monthlyFloat, 0, 15, 255, 0);
fill(colorMap);
noStroke();
translate(10, 0, 0);
rect(0, 0, 10, 10);
}
popMatrix();
}
void loadMonth2() {
pushMatrix();
for (int i = 0; i < 50; i++) {
XMLElement xml = new XMLElement(this, "unemployment.xml");
XMLElement stateData = xml.getChild(i);
XMLElement monthlyData = stateData.getChild(2);
String monthlyNumber = monthlyData.getContent();
float monthlyFloat = float(monthlyNumber);
float colorMap = map(monthlyFloat, 0, 15, 255, 0);
fill(colorMap);
noStroke();
translate(10, 0, 0);
rect(0, 10, 10, 10);
}
popMatrix();
}

Replies(4)

PhiLho

Re: Loop through XML data efficiently

2 years ago

I don't get it.
First, indeed you load the file on each loop. Why don't you put it outside of the loop? Or, better, directly in setup(), by putting it in a global variable (declared outside of setup()).
Likewise, don't duplicate a function, add parameters to it and use them where you have variances between the functions.

kpowe11

Re: Loop through XML data efficiently

2 years ago

That's what I'm not sure how to do. How do I change the parameters of the loop such that the loop cycles through 50 times using the number variable and then moves from number 3 to 4, 5, 6 cycling through 50 times for each of those?

void loadMonth() {
pushMatrix();
int number = 3;
for (int i = 0; i < 50; i++) {
XMLElement xml = new XMLElement(this, "unemployment.xml");
XMLElement stateData = xml.getChild(i);
XMLElement monthlyData = stateData.getChild(number);
String monthlyNumber = monthlyData.getContent();
float monthlyFloat = float(monthlyNumber);
float colorMap = map(monthlyFloat, 0, 10, 255, 0);
fill(colorMap);
noStroke();
translate(10, 0);
rect(0, 0, 10, 10);
}

mbraendle

Re: Loop through XML data efficiently

2 years ago

As phi.lho said, you should move

XMLElement xml = new XMLElement(this, "unemployment.xml");

outside the loop. In my opinion, you should even split the processing of the XML data and the drawing of your data, which makes your code much more flexible. This can be done by assigning the values to an array, and then using the array in a separate drawing routine.

Regarding your second question, you just program a double-loop:

In your global variable definition:

int num_stateData = 50;
int num_monthlyData = 4;
int monthlyData_offset = 3;
float [][] colorMap;

( If you have control over the XML file, you could even read those parameters from the XML file and then create the array dynamically. For our case, I do this by using a count="" attribute in the XML).

In your setup() part:

colorMap = new float[num_stateData][num_monthlyData];
.
.
.
loadMonth();

void loadMonth() {
XMLElement xml = new XMLElement(this, "unemployment.xml");
for (int i = 0; i < num_stateData; i++) {
XMLElement stateData = xml.getChild(i);
for (int j = 0; j < num_monthlyData; j++) {
XMLElement monthlyData = stateData.getChild(j + monthlyData_offset);
String monthlyNumber = monthlyData.getContent();
float monthlyFloat = float(monthlyNumber);
colorMap[i][j] = map(monthlyFloat, 0, 10, 255, 0);
}
}

kpowe11

Re: Loop through XML data efficiently

2 years ago

Perfect. Thanks. That works and definitely loads much more quickly.

Top Reply