Autodownload pretrained ResNet

[alexander-g]

• Added checks to .set_parameters()
• Added weights= parameter to ResNet. Can be a path to a ".pkl" file containing module weights as returned by .get_paramters() or "imagenet" which automatically downloads and caches weights in ~/.elegy/downloads

import PIL, urllib

fname,_ = urllib.request.urlretrieve('https://upload.wikimedia.org/wikipedia/commons/e/e4/A_French_Bulldog.jpg')
im = np.array(PIL.Image.open(fname).resize([224,224])) / np.float32(255)

r18 = elegy.nets.resnet.ResNet18(weights='imagenet')
assert elegy.Model(r18).predict(im[np.newaxis]).argmax() == 245   #ImageNet label #245: French Bulldog

@cgarciae

• How much of this do you think should be added to tests?
• The weight files are currently hosted on DropBox. I think that's not a long-term solution. I've heard GitHub offers unlimited file hosting for assets with each realease. Maybe upload them on the next version?

[codecov-io]

Codecov Report

Merging #136 (67d8cee) into master (78777ff) will decrease coverage by 0.40%.
The diff coverage is 87.17%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
- Coverage   79.25%   78.84%   -0.41%     
==========================================
  Files         110      110              
  Lines        5143     5338     +195     
==========================================
+ Hits         4076     4209     +133     
- Misses       1067     1129      +62     

Impacted Files	Coverage Δ
elegy/nets/resnet.py	74.25% <57.89%> (-4.06%)	⬇️
elegy/module.py	90.59% <93.10%> (+1.66%)	⬆️
elegy/model/model_base.py	76.42% <100.00%> (+2.12%)	⬆️
elegy/module_test.py	99.81% <100.00%> (+<0.01%)	⬆️
elegy/nets/resnet_test.py	100.00% <100.00%> (ø)
elegy/losses/loss_modes.py	0.00% <0.00%> (-100.00%)	⬇️
elegy/metrics/metric_modes.py	0.00% <0.00%> (-100.00%)	⬇️
elegy/callbacks/progbar_logger.py	63.52% <0.00%> (-14.44%)	⬇️
elegy/model/model.py	69.17% <0.00%> (-2.88%)	⬇️
elegy/model/__init__.py	100.00% <0.00%> (ø)
... and 3 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 78777ff...67d8cee. Read the comment docs.

[cgarciae]

1. Maybe we can add the image somewhere in the repo or as an asset.
2. We can create the repo elegy-assets to upload stuff in that case.

[charlielito]

Another option is to use a cloud based solution like GCP. GCP storage is free up to 10 GB