Why do we need "num_use" for each dataset?

[LiyaoTang]

Thank you for the great works!

When training with your code, I found that there is a "num_use" (or, "NUM_USE") specified for each dataset, and it seems to be used for specifying the maximal number of examples used in each dataset.

My confusion is that if there is any reason to choose different number for different datasets?
(e.g. VID is limited to 100000 while youtube-bb, detection datasets are not limited as "NUM_USE=-1")

Moreover, would setting NUM_USE causes a situation where not all examples in a datasets are used in training?
(e.g. it seems there are 1,181,113 labeled frames in VID datasets >> 100,000)

Thanks in advance

[ZhiyuanChen]

#302