How to interpret these datafiles

The data files use the .npz extension, which should be opened with the command numpy.load in a Python3 script. In a given file f, subfiles can be accessed by calling f[class], where class can have the values cent0, cent1, cent2, cent3, respectively representing the 0-10%, 10-20%, 20-30%, 30-40% centrality classes. Each centrality class has two or three columns, representing the x-axis, y-axis, and error in y (if present).