Question

I am not that experienced with Java/Android programming.
I have an array of floats that i have logged, and i want to plot them against time.
I just want to see what the data looks like, I don’t really need to plot it in the app itself, although it would be handy. I am looking for the simplest possible way to do this.
I have looked around at libraries (graph view and achartengine) which plot graphs in the app, but when i imported them into eclipse, there were errors everywhere on the demo code.
Maybe it would be easier to export the array so I can plot it on the computer, e.g. to a csv file (for excel)? But, I can only find stuff on databases with csv files. Someone please point me in the simplest direction! 😀
Thanks

Answer 1

Both ways are quite simple.

1. You may draw your values at any View by overriding its draw(Canvas) method. The thing which will take the most time is converting your values to view’s coordinates, which is actually primitive algebra.

2. You don’t need any tools to generate *.csv files – it has very simple format, you may create it by yourself. In your case its content will look like this:

   "time","value"
   "12300000","78.99"
   "12340000","89.77"
   ...
   

Here is the code, which will produce such file:

    long[] time = ...; // this contains your time values
    float[] values = ...; // this contains your float values
    File outFile = new File("/mnt/sdcard/my_output_file.csv");

    BufferedWriter buffWriter = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(outFile)));
    buffWriter.write("\"time\",\"values\"\n");
    buffWriter.flush();

    for (int i = 0; i < values.length; i++) {
        buffWriter.write("\"" + time[i] + "\",\"" + values[i] + "\"\n");
        buffWriter.flush();
    }

    buffWriter.close();