differential calculation modified

[inamoto85]

Hi Bastula,
0 should be first appended at the end of the cumulative DVH and np.diff can then be used to differentiate the DVH.
In this way the information in last bin of the cumulative DVH can be preserved, comparing to append a 0 after the diff manipulation.

I have not understood the * -1. Would you explain a little bit?

And The modification would indeed fail related unittest (as you can see from the logfiles), But I believe this reasoning is correct.

Thank you for your time,

unittest.log

[bastula]

Hi Hideki,

I agree with this patch. I just did some testing and could verify your findings that the last cumulative count bin gets removed in the current implementation.

Regarding the * -1, I think it was a holdover from the original implementation from dicompyler and can be safely removed as there is an np.abs call.

I was actually hunting down this discrepancy some time ago but wasn't able to find it. Thanks!

I will merge in the changes with updated unit tests.