Extracts data for a specified group from a PX4 log file

extract_group.m

function group = extract_group(logfile, label)
%EXTRACT_GROUP Extracts data for the specified group from a PX4 log file
%   EXTRACT_GROUP(LOGFILE,LABEL) extracts data for the group LABEL from the
%   PX4 log file LOGFILE, and returns a struct whose fields are the members
%   of that group. The returned struct also has a field TIME_StartTime
%   containing the timestamps for the data.

index = find(logfile == '.', 1, 'last');
if isempty(index)
    basename = logfile;
else
    basename = logfile(1:index-1);
end

data_file = [basename '_' label '.csv'];

status = system(sprintf('python sdlog2_dump.py %s -f %s -m TIME -m %s',...
    logfile, data_file, label));

if status ~= 0
    error('Error parsing log file %s', label, logfile)
end

log = importdata(data_file);

if ~isstruct(log) || ~isfield(log, 'colheaders') || ~isfield(log, 'data')
    error('Error reading data for group %s from log file %s', label, logfile)
end

label_format = [label '_%s'];
labels = cell(1, length(log.colheaders));
data = cell(1, length(log.colheaders));
for i=1:length(log.colheaders)
    if strcmp(log.colheaders{i}, 'TIME_StartTime')
        labels{i} = 'TIME_StartTime';
    else
        labels{i} = sscanf(log.colheaders{i}, label_format);
    end
    data{i} = log.data(:,i);
end

group = cell2struct(data, labels, 2);

end

Note that the extraction script sdlog2_dump.py must be in the current directory