3.4. Get Sample Data

The example will show how to get the root recording and some information about it. We will perform the following steps:

• get root recording

• get some general informations about the recording

• get some infos about all used recording devices

• get some infos about all recorded channels

When more than one recording device was used, the root recording provides access to the channels as if they were recorded with one device.

rasch@rasch:~> octave
GNU Octave, version 2.1.50 (i686-pc-linux-gnu).
...

octave:1> ra=ra_lib_init
ra = 145017272
octave:2> meas=ra_meas_open(ra, '/home/rasch/ecgs/AT011030_rdi.ART', 0)
meas = 145244336
octave:3> rec=ra_rec_get_first(meas, 0)
rec = 145421120
octave:4> num_ch=ra_rec_get_info(rec, 'rec_num_channel')
num_ch = 5
octave:5> ch_all=[];
octave:6> for i=0:(num_ch-1)
> ch=ra_raw_get(rec, i, 0, 10000); 
> ch_all=[ch_all ch'];
> endfor
octave:7> whos ch_all

*** local user variables:

prot  type                       rows   cols  name
====  ====                       ====   ====  ====
 rwd  matrix                    10000      5  ch_all

octave:8> samplerate=ra_ch_get_info(rec, 0, 'ch_samplerate')
samplerate = 1600
octave:9> x=0:9999;
octave:10> x = x / samplerate;
octave:11> figure(0); plot(x, ch_all(:,1));
octave:12> figure(1); plot(x, ch_all(:,2));
octave:13> figure(2); plot(x, ch_all(:,3));
octave:14> figure(3); plot(x, ch_all(:,4));
octave:15> figure(4); plot(x, ch_all(:,5));
octave:16>

Figure 3-1 shows a screenshot of Octave after performing the above steps. Each plot window on the right side shows a recording channel. The x-axis is in seconds.