[SciPy-user] what type of data for scipy.stats.mannwhitneyu ?

[Eric Emsellem]

Hi,
I am trying to compare two datasets with scipy.stats.mannwhitneyu(x,y).
HOwever I cannot make it work. It always gives me:

TypeError: data type not understood
or
TypeError: Not a numeric type

So the question is: what type should "x" and "y" be?
(I tried arrays, tuples, etc)... If someone can provide me with a 
specific example (explicit x, and y for which this functions works), 
that would help.

Thanks!

Eric