Drawing GPS coordinates

Programming Questions

solrrt

in Programming Questions • 2 years ago

I recently discovered Processing and thought of a little project I'd like to try for myself and was hoping I could find some help here!

I've got some LAT/LON coordinate data in a standard text file which I'd like to display, but all of the examples I've found rely on the .gpx format.

A sample of the data is below, it's just a datetime stamp, latitude, longitude:

_{07-01-2010 01:05:01,34.5940361022949,98.4206924438477
07-01-2010 01:05:58,34.5942306518555,98.4199905395508}

My question has a couple of parts, I know how to read this file/data into processing, but how do I split each line and only read the latitude and longitude values?

Once I've got those values declared as their own variables, would using the map() function be the best method to display them? I've read the reference on it and it's a little fuzzy to me.

Any examples or tips anyone could post would be awesome.

Replies(3)

PhiLho

Re: Drawing GPS coordinates

2 years ago

" all of the examples I've found rely on the .gpx format"
Indeed. At least you had the good idea to do searches (not all beginners do that). Just a little reminder that also escape lot of beginners: search from the search field of Processing.org, not from here, as it will give lot more hits (from old forum and main site as well).

" how do I split each line"
Using... split()!

" only read the latitude and longitude values"
Once you have split on commas, you get an array of strings. You access the coordinates on the indices 1 and 2 and convert them with float().

" would using the map() function be the best method to display them?"
map() won't display them... But if you know the original range (you can compute it from the array of values), it allows to map the GPS values to the display coordinates (0 to width-1, 0 to height-1).
Then you can use line() to show a trajectory, or point() to show a cloud of points, depending on what the coordinates represent.

voskull

Re: Drawing GPS coordinates

2 years ago

I've had similar question in the past,

i've come-up with some code below, i'm sure they might be a better and more elegant way of doing so...

my txt file is formatted in 3475, 3493.3, 23

personally i'm not sure if the code below will split the timestamp correctly, i'd think the below code will give you timestamp , lat , long.

so u can always use excel or similar to clean-up to txt file before passing it processing

hope it helps,

if you lost, i can send a project file with my data set ;)

String[] lines;
int index = 0;
void setup() {
// put setup stuff here. ( size, renderer, etc )
size(600, 600);
// reads the txt file
lines = loadStrings("your_txt_file_inside_data_folder.txt");
}
void draw() {
if (index < lines.length) {
String[] pieces = split(lines[index], ',');
float timeStamp = float(pieces[0]);
float lat = float(pieces[1]);
float long = float(pieces[2])
# map your values to something within range of the canvas
# eg: float latm = map(lat,min,max,new min,new max);
#draw some stuff
stroke(255,0,0);
point(lat,long);
} # end of if
index = index + 1; #increment index so the loop reads the next line
}

to draw lines, i've use a dirty method (i'd think there is more elegant ways)

String[] nextpieces = split(lines[index+1], ','); #grabs the next line and store it in the String Array nextpieces
and change the condition for the loop so it's stop at the line before last ( out of bound error otherwise )
if (index < lines.length) { # to
if (index < lines.length-1) {

theprof

Re: Drawing GPS coordinates

2 years ago

Hi, this has been asked many times before, you can download my example from: http://forum.processing.org/topic/mapping-gps-locations-to-a-2d-u-s-map

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