added describe and scoreatpercentile in frame.py

[ghost]

Added two methods in frame.py: describe, which returns a DataFrame with summary statistics of each columns of the original DataFrame (with index=columns), and scoreatpercentile, which calculate the score at the given percentile.

When I play around with a dataset I use this describe thing a lot so I thought it would be convenient to have this with DataFrame.

I think this is crudely implemented so if you think there is a better way please let me know!

-Joon

[wesm]

I tweaked a couple of things (can use the apply function in the scoreatpercentile function), I renamed scoreatpercentile to quantile (analogous to R), and I transposed the result of describe (which can always be transposed back)

wesm@ffc49d7

thanks for the patch!

[ghost]

Thanks for merging this! By the way, do you prefer me to ask you first before I send a pull request? Please let me know.

[wesm]

Nope, feel free to submit pull requests whenever you like. Just make sure to stay up-to-date on the upstream changes =)

[ghost]

Sounds good. Thanks!