we are missing only out of entriesso we can afford to remove them remember that we can index scipy array with another array sp isnan(yreturns an array of booleans indicating whether an entry is not number using ~we logically negate that array so that we choose only those elements from and where does contain valid numbers [~sp isnan( ) [~sp isnan( )to get first impression of our datalet us plot the data in scatter plot using matplotlib matplotlib contains the pyplot packagewhich tries to mimic matlab' interface-- very convenient and easy-to-use one (you will find more tutorials on plotting at import matplotlib pyplot as plt plt scatter( ,yplt title("web traffic over the last month"plt xlabel("time"plt ylabel("hits/hour"plt xticks([ * * for in range( )]['week % '% for in range( )]plt autoscale(tight=trueplt grid(plt show(in the resulting chartwe can see that while in the first weeks the traffic stayed more or less the samethe last week shows steep increase