Scatter plot interprets NaN as 0 value.

[ianp]

If I have a data frame which contains NaN values, say by merging or joining 2 different data sets, when vincent creates Scatter plants it interest these as zero rather than omitting them. For example the fragment below displays all of the data squashed up in the top right corner of the plot.

df = pd.DataFrame({'Data 1': [1115, np.nan, np.nan, 1128, 1145, 1173,  1115,    1162],
                   'Data 2': [1142,   1127,   1152, 1118, 1161, 1119, np.nan, np.nan]},
                   index=[ 536,   456,    567,   678,  453,  621,   343,     398])
vincent.Scatter(df, width=800).display()

There should be a way to either ignore NaN values and/or easily control the ranges that are plotted (i.e. limit the values on both axes).

I had a brief look through the source and couldn't see an obvious way to do either.