Add augmentations on the Trainer class, Detectron2

add_augmentations.py

class MyTrainer(DefaultTrainer): 
  
    @classmethod
    def build_train_loader(cls, cfg):
        mapper_train = DatasetMapper(cfg, 
                       is_train=True, 
                       augmentations=[ #Apply a sequence of augmentations.
                                      T.RandomFlip(prob=0.5, horizontal=False, vertical=True),
                                      T.RandomFlip(prob=0.5, horizontal=True, vertical=False),
                                      T.RandomRotation(angle=[0, 90, 180, 270], sample_style="choice"),
                                      T.RandomApply(T.RandomBrightness(0.9, 1.1), prob=0.5),
                                      T.RandomApply(T.RandomContrast(0.9, 1.1), prob=0.5),
                                      T.RandomApply(T.RandomSaturation(0.9, 1.1), prob=0.5),
                                      T.RandomApply(T.RandomLighting(0.9), prob=0.5),
                                      ]
                       )
        return build_detection_train_loader(cfg, mapper=mapper_train)