The timestamp is the first column in the current CSV format that MusePlayer uses. What difficulty are you having accessing it, specifically?
As you’ve clearly noticed, the data in the current CSV format is not organized into columns by OSC path name. MusePlayer does have a feature to filter the data by its OSC paths, which should in theory allow you to create separate CSV files for each path that you’re interested in. CSV files with only data for a single path would be easier to import because they represent square matrices, which software packages light MATLAB and R (and I’m guessing Rapidminer, although I’m not personally familiar with it) tend to like. Unfortunately, I noticed a bug in MusePlayer where the OSC path filtering cannot tell the difference between two paths like “/muse/eeg” and “/muse/eeg/quantization”. We’ve got a fix for this that allows the user to specify a regular expression to match rather than just a string, and that will be included in the next release of the SDK (which should happen fairly soon).
In the meantime, before we release the fix, you may have to write a script of your own that parses the CSV files into a format that Rapidminer can understand. For instance, a Python script that goes through the file line by line, creating and appending to different lists depending on the OSC path specified on each line.
Another possible workaround: If you have MATLAB or Octave (essentially a free, open-source MATLAB), you should be able to import the .mat files that MusePlayer produces and then use the built-in CSV writing methods to export whatever variables you are interested in to CSV files that Rapidminer is more likely to be able to read.
Hope this helps, and we’ll let you know when the next SDK update is available.