I was learning lesson3-camvid.ipynb, all outputs of the previous steps seem correct except when running the following line of code:
data.show_batch(2, figsize=(10,7), ds_type=DatasetType.Valid)
the output shows several images, but they all look the same:
no matter how many time i ran the code or change the rows to show.
Here is the notebook with strange output that i wrote according to the original notebook, if anywhere was wrong, could you please do me a favor to point it out ?
some of the codes is as follows:
%reload_ext autoreload
%autoreload 2
%matplotlib inline
from fastai.vision import *
from fastai.callbacks.hooks import *
from fastai.utils.mem import *
path = untar_data(URLs.CAMVID)
path_lbl = path/'labels'
path_img = path/'images'
fnames = get_image_files(path_img)
lbl_names = get_image_files(path_lbl)
img_f = fnames[0]
img = open_image(img_f)
get_y_fn = lambda x: path_lbl/f'{x.stem}_P{x.suffix}'
mask = open_mask(get_y_fn(img_f))
src_size = np.array(mask.shape[1:])
codes = np.loadtxt(path/'codes.txt', dtype=str)
size = src_size // 2
bs = 4
src = (SegmentationItemList.from_folder(path_img)
.split_by_fname_file('../valid.txt')
.label_from_func(get_y_fn, classes=codes))
data = (src.transform(get_transforms(), size=size, tfm_y=True)
.databunch(bs=bs)
.normalize(imagenet_stats))
data.show_batch(2, figsize=(10, 7)) # different outputs every time
data.show_batch(2, figsize=(10, 7), ds_type=DatasetType.Valid) # outputs always look the same
Just they were taken milliseconds apart! This is due to show_batch() grabbing the first ‘x’ photos in its dataloader. If we assume this is car data continuously being gathered, this behavior would make sense wouldn’t it?
