And here is some simple example of using my scripts:
# Path of annotations, in this case folders with audio tracks
# should be placed in /home/user/Magnatagtune/
filename = '/home/user/Magnatagtune/annotations_final.csv'
# Open file with annotation
file = open(filename, 'rb')
# Creating CSVParser object
mangaCSV = CSVParser(file)
# Getting names of songs in singer category. Return list of string
print 'Files with singer category'
print mangaCSV.printFilesInCategory('singer')
# Getting all tags of track
print 'Categories of burnshee_thornside-rock_this_moon-01-bad_bad_luck-117-146'
print mangaCSV.printCategoriesOfFile('burnshee_thornside-rock_this_moon-01-bad_bad_luck-117-146')
MagnaTagATune is a nice dataset because of quite good annotation and large number of tracks. It can be used not only for genre classification but also mood classificationinstruments classification/detection.
You can download whole dataset from this place