ArrayList trouble

Programming Questions

lscarmic

in Programming Questions • 2 years ago

My program reads distances and altitudes from all Garmin files (xml) present in the sketch folder. At the end of setup() i have two global ArrayLists. One is called altArrays and one is called distArrays. The are both structured the same, i.e. they are two-dimensional. So, for example, altArrays[0] contains an ArrayList of all of the altitudes for the first xml file in the sketch folder. altArrays[1] contains an ArrayList of all the altitudes for the second xml file, and so on. Here's the code that gets me there:

XMLElement xml;
float mapX1, mapX2, mapY1, mapY2;
float w_start, w_end, h_start, h_end;
int pad = 100; // sizes the window padding around the edgemost points
ArrayList altArrays = new ArrayList();
ArrayList distArrays = new ArrayList();
void setup() {
size(100, 100);
File dir = new File("/Users/leecarmichael/Documents/Processing/bikeViz_alt/data");
String[] files = dir.list();
println(files.length + " files present.");
for(int i=0; i<files.length; i++){
xml = new XMLElement(this, files[i]);
GarminXML data = new GarminXML(xml);
altArrays.add(data.getAltitudes());
}
for(int i=0; i<files.length; i++){
xml = new XMLElement(this,files[i]);
GarminXML data = new GarminXML(xml);
distArrays.add(data.getDistances());
}
}
void draw(){

My question is, now what? :)

My assumption is that if i'm going to use distance for the x-axis and altitude for the y-axis, I'm going to need all of these values to be integers (or double). What is the best way to get them there? My first thought was to simply index through the ArrayLists and somehow convert (perhaps via casting) the values to primitives. I can't seem to get that to work. Second approach was to just try some sort of conversion like:

String[] distances = new String[distArray.size()];
distArray.toArray(distances);

but it appears the two-dimensions are making this difficult. So I'm now out of ideas.

Thanks for the help.

Lee C

Replies(11)

fiveagon

Re: ArrayList trouble

2 years ago

Use Generics with your ArrayLists, otherwise it's hard for people to understand. I can't tell if you have Lists of Strings or Integers or what.

I'm assuming the GarminXML methods return a List<String>, so ...

List<List<String>> altArrays = new ArrayList<List<String>>();
List<List<String>> distArrays = new ArrayList<List<String>>();

These can probably be used in setup() only because you probably aren't going to use the strings in your program.

Also, lines 17-27 can be in one loop.

for (File xmlFile : files) { // For-each loop
XMLElement xml = new XMLElement(this, xmlFile); // you don't need "xml" at top of program
GarminXML data = new GarminXML(xml);
altArrays.add(data.getAltitudes());
distArrays.add(data.getDistances());
}

Ok, then you'll have to convert the Strings to numbers that you can use. I suggest looking at Float.valueOf(String). (Integer, Double, Float, etc. all have a similar method).

lscarmic

Re: ArrayList trouble

2 years ago

Ok, I've made a few modifications but am still having some trouble. Here's where I am:

ArrayList<Float> AltArrayList = new ArrayList();
//ArrayList distArrayList = new ArrayList();
Float a;
float[] altFloat;
float c;
for(int i=0; i<files.length; i++){
xml = new XMLElement(this, files[i]);
GarminXML data = new GarminXML(xml);
AltArrayList = data.getAltitudes();
for(int k=0;k<AltArrayList.size(); k++){
a = AltArrayList.get(k); //pick one value out of the array and assigns it to "a". probably not necessary.
altFloat = AltArrayList.altFloat(); //ERROR. the function altFloat() does not exist.
println(altFloat);
}
}

I got some of this from an example I saw somewhere for converting an Object to a Primitive. It looks like this (which compiles and works fine):

void setup(){
Float FloatValue = 123.3;
float floatValue = FloatValue.floatValue();
println(floatValue);
}

So I don't know what is going on. Maybe this example and what I'm trying to do are apples and oranges. Suffice it to say, I'm confused.

By the way, here's the getAltitudes() method from my GarminXML class:

ArrayList getAltitudes(){
XMLElement[] kids = file.getChildren("Activities/Activity/Lap/Track/Trackpoint/AltitudeMeters");
ArrayList allAltitudes = new ArrayList();
for (XMLElement kid : kids) {
String site = kid.getContent();
allAltitudes.add(site);
}
return allAltitudes;
}

Maybe it's something in there messing it up.

Thanks for all of the help guys. Sorry I'm having such a tough time with this.

Lee

jeff_g

Re: ArrayList trouble

2 years ago

I'm not sure what this is...

altFloat = AltArrayList.altFloat();

Perhaps you mean to pass it to an Array?

altFloat = (float[]) AltArrayList.toArray();

Your putting in a String, and trying to pull out a float. If that doesn't work right, you could try.

a = (String) AltArrayList.get(k);
float afloat = Float.valueOf(a).floatValue();

PhiLho

Re: ArrayList trouble

2 years ago

The advice on generics should also be applied inside your class:

ArrayList<Float> getAltitudes(){
XMLElement[] kids = file.getChildren("Activities/Activity/Lap/Track/Trackpoint/AltitudeMeters");
ArrayList<Float> allAltitudes = new ArrayList<Float>();
for (XMLElement kid : kids) {
String site = kid.getContent();
allAltitudes.add(float(site));
}
return allAltitudes;
}

And to do your stated objective, you need a different structure:

ArrayList<ArrayList<Float>> altArrayList = new ArrayList<ArrayList<Float>>();
for(int i=0; i<files.length; i++){
xml = new XMLElement(this, files[i]);
GarminXML data = new GarminXML(xml);
ArrayList<Float> alts = data.getAltitudes();
altArrayList.add(alts);
}

To use the data, you have to do:
ArrayList<Float> alts = altArrayList.get(n);
float alt = alts.get(idx).floatValue();
(where n and idx are some indexes of loops)

lscarmic

Re: Re: ArrayList trouble

2 years ago

ok. i think i've gotten all of the generic stuff straightened out finally.

however, when i try to run the new structure you suggest, i get a "cannot find a class or type named "ArrayList<ArrayList<Float>>"

thoughts?

fiveagon

Re: ArrayList trouble

2 years ago

Maybe we should start with one xml file and then work our way up to more than one. Can you give us a sample xml file?

PhiLho

Re: ArrayList trouble

2 years ago

" when i try to run the new structure you suggest, i get a "cannot find a class or type named "ArrayList<ArrayList<Float>>""
I just tried inside PDE, and it works (the declaration). You should show the current state of your code.

lscarmic

Re: Re: ArrayList trouble

2 years ago

Here's the whole thing:

XMLElement xml;

float mapX1, mapX2, mapY1, mapY2;

float w_start, w_end, h_start, h_end;

int pad = 100; // sizes the window padding around the edgemost points

void setup() {

size(100, 100);



File dir = new File("/Users/leecarmichael/Documents/Processing/bikeViz_alt/data");

String[] files = dir.list();

println(files.length + " files present.");

println(files);





ArrayList<ArrayList<Float>> altArrayList = new ArrayList<ArrayLIst<Float>>();

//ArrayList<Float> altArrayList= new ArrayList<Float>();

for(int i=0; i<files.length; i++){

xml = new XMLElement(this, files[i]);

GarminXML data = new GarminXML(xml);

altArrayList<Float> alts = data.getAltitudes();

altArrayList.add(alts);

}

}

void draw(){

}

obviously some of the variables aren't used. there are some commented sections that i deleted from the post.

and here's the GarminXML. i deleted the other methods since they're aren't being used yet.

class GarminXML{
XMLElement file;
GarminXML(XMLElement tempXML){
file = tempXML;
}
ArrayList<Float> getAltitudes(){
XMLElement[] kids = file.getChildren("Activities/Activity/Lap/Track/Trackpoint/AltitudeMeters");
ArrayList<Float> allAltitudes = new ArrayList<Float>();
for (XMLElement kid : kids) {
String site = kid.getContent();
allAltitudes.add(float(site));
}
return allAltitudes;
}

fiveagon

Re: Re: ArrayList trouble

2 years ago

ArrayList<ArrayList<Float>> altArrayList = new ArrayList<ArrayLIst<Float>>();

You have a typo.

lscarmic

Re: ArrayList trouble

2 years ago

dammit

lscarmic

Re: ArrayList trouble

2 years ago

ok guys, i think i finally got it working. time to shut this thread down (gone on way too long).

BIG thanks to everyone. i learned a lot here.

Lee

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