Lesson 1 Discussion ✅


(Jeremy Howard (Admin)) #1205

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(Yash Mittal) #1206
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(Jeremy Howard (Admin)) #1207

This seems quite clear?..


(Yash Mittal) #1208

Ok sorry could you direct me where else can I ask my question if it is not answered on forum


(Vignesh J) #1209

Hi,
I would like to know how get_transforms() method works in detail.
Providing the link to the repository [https://github.com/fastai/fastai/blob/master/fastai/vision/transform.py]
1.What are affines and why it is used?
2.How changing brightness,contrast,cropping or zooming would help in satellite images,for example finding water resources.It can be any use case.
Just need a basic explanation of how this is used to manipulate images.Does this manipulation correlate to higher accuracy?
Also, How does this transformation techniques correspond to this paper[http://cs231n.stanford.edu/reports/2017/pdfs/300.pdf]
Thanks!


(Francisco Ingham) #1210

Hey, @ymittal23! This is the correct place to ask but you should not tag Jeremy for code-specific questions.

Tensor b is double the specified batch size because the validation set batch size is double the training set batch size in fastai (and the problem here concerns the validation set).

When does this bug arise? When you call fit or when it is finishing an epoch?


(Francisco Ingham) #1211

How does your csv file look like? Can you send a screenshot?


(Andrea de Luca) #1212

(Rebecca Reilly) #1213

Can anyone help with this error in the lesson 1 notebook:

OSError: cannot identify image file ‘/home/jupyter/.fastai/data/oxford-iiit-pet/images/Birman_141.jpg’

I’ve re-pulled the repo and continue to get the same error


(Yash Mittal) #1214

The bug is arising when epoch is completed. The error is coming with fbeta matric only with accuracy it is working fine.


(bhaskar rao) #1215

how access the file names when we use learn.predict(is_test=True) ?

data.test_ds.fnames shows ‘ImageClassificationDataset’ object has no attribute ‘test_ds’


(Francisco Ingham) #1216

Can you run len(data.valid_ds) and tell me what is the output?


(bhaskar rao) #1217

it prints the len ‘110924’


(Yash Mittal) #1218

111110
If we restart kernel and run it again it will be different but is almost in same range.
For eg it changed to 110812 when I run the kernel again by restarting.


#1219

Getting a 404 from https://docs-dev.fast.ai/troubleshoot.html. Did the documentation move?


(Pranav Bajaj) #1221

Thank you


(Rebecca Reilly) #1222

Experiencing a corrupted file in lesson 1 pets data, anyone know how to get around this? The file exists, and I get “OSError: cannot identify image file ‘/home/jupyter/.fastai/data/oxford-iiit-pet/images/Birman_141.jpg’” when I attempt the Jupiter notebook


(Kaspar Lund) #1223

have you tried to delete the dataset and let the notebook download it again


(Rebecca Reilly) #1224

I haven’t, I wasn’t sure if our notebook was downloading from a URL or if the zipped data existed from the git pull?


(Kaspar Lund) #1225

have a look in the notebook. i belive that the line untar also downloads.
anyway you could also just delete the offensive file