'This Iter will provide roi data to Fast R-CNN network
:param roidb: must be preprocessed
:param batch_size: must divide BATCH_SIZE(128)
:param shuffle: bool
:param ctx: list of contexts
:param work_load_list: list of work load
:param aspect_grouping: group images with similar aspects
:return: ROIIter'

def __init__(self, roidb, batch_size=2, shuffle=False, ctx=None, work_load_list=None, aspect_grouping=False):

    super(ROIIter, self).__init__()
    self.roidb = roidb
    self.batch_size = batch_size
    self.shuffle = shuffle
    self.ctx = ctx
    if (self.ctx is None):
        self.ctx = [mx.cpu()]
    self.work_load_list = work_load_list
    self.aspect_grouping = aspect_grouping
    self.size = len(roidb)
    self.index = np.arange(self.size)
    self.data_name = ['data', 'rois']
    self.label_name = ['label', 'bbox_target', 'bbox_weight']
    self.cur = 0
    self.batch = None
    self.data = None
    self.label = None
    self.reset()
    self.get_batch()
