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Author: torontoai

[D] What other basic classifiers are used for boosting?

I know that decision stumps are used as basic classifiers in boosting, but what other basic classifiers can be used? Can we use any classifier? SVMs are pretty accurate, and boosting, well, boosts the algorithm. So why not use SVMs as the basic binary classifier and boost the hell out of it with AdaBoost? What’s stopping us?

PS: If this is a beginner question, tell me to delete it.

submitted by /u/PartlyShaderly
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[D] skip-GANomaly and general issues with reproduction of papers

[D] skip-GANomaly and general issues with reproduction of papers

Hi all, I’m currently working through an implementation of skip-GANomaly, a paper on anomaly detection using an adversarially trained auto-encoder. In a nutshell, they train an auto-encoder over normal examples. Abnormal examples at test time will have poorer reconstruction, and thus higher loss, as they come from a different image distribution than normal examples.

However, this paper contains no code. Additionally, the paper contains no clear definition of their network architecture. The only description of the network architecture is a figure shown beneath:

Problematic Figure of skip-GANomaly

As there is no explanation, I interpret the initial convolutional maps to come from a single convolution from 3 -> 64 channels; each following arrow is LReLU, Conv, and BN, so a nonlinearity would be applied afterwards.

However, for any initial convolutional feature maps concatenated over, as shown in the image, reconstruction could be perfect without any of the rest of the network as a single convolution would be necessary to go from 64 + 64 -> 3 channels. This convolution could just learn the inverse of the initial convolution which created the feature maps from the image. I could be misinterpreting this, so if anyone could enlighten me, that’d be great. I’d imagine that the feature maps resulting from the first convolution could not be concatenated, unless feature maps are defined to be subsequent to batch norm and activations. If bn and LReLU is included in the initial convolution, this is not described anywhere in the paper.

In general, how frequent are papers published without code / with difficulties in obtaining the architecture or training specifications to reproduce the work? I’m a student, and this is the first time I’ve diverged from large SOTA papers with thousands of citations. I was surprised to encounter a lot of the ambiguity in this paper.

submitted by /u/good_rice
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[N] Daily ML Tips from a Graduate Student

Hey, I am a Masters student and a TA for Machine Learning at my uni. What i noticed is that while teaching my students i would learn concepts much quicker. Hence why started a new twitter channel @Daily_ML_Tips so i can learn and teach more people directly. Twitter Link Here

Feel free to give me a follow and tweet at me if u have any specific ML questions. 🙂

have a great day

submitted by /u/theThinker6969
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[D] Style & content disentanglement of temporal structure in videos

Back there with another question, have anyone considered disentangling/learning on style of temporal structure in videos ?

I have seen many examples of ‘artistic’/photorealistic style transfer usage on single images/frames, and also using a temporal constraint to transfer it coherently.. But i ain’t askin’ about spatial style transfer enforced by temporal structure, but rather exploiting the temporality of different videos (films would be very useful i can imagine) and transferring ’em..

submitted by /u/ad48hp
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[P] comparing accuracy between two encoded datasets

I have two datasets that I ran a label encoder and onehotencoder on. A is the actual and B is the prediction.

I would like to be able to come up with the accuracy between the two. For example in B, the last row is different so I would like calculate an accuracy of 75%.

Is there a nice pythonian way of doing this?

A

0 1 0
1 0 0
0 0 1
1 0 0

B

0 1 0
1 0 0
0 0 1
0 1 0

submitted by /u/rxo85
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[D] ShuffleNet V2 on MNIST dataset

Few days ago ,I see a article introduceed ShuffleNet V2 .

Based on my curiosity I trained ShuffleNet V2 on MNIST datase, and I got 99.14% accuracy .
( code here : https://github.com/allen108108/Model_on_MNIST/blob/master/MNIST%20-%20ShuffleNetV2.ipynb ).

The result looks good , but I got higher accuracy ( almost 99.5% ) when I trained a typically CNN model on the same dataset
( code here : https://github.com/allen108108/Model_on_MNIST/blob/master/MNIST%20-%20CNN.ipynb).

Is that normal situation ? Did I make some mistakes ?

PS : the ShuffleNet V2 model that I used : https://github.com/opconty/keras-shufflenetV2

submitted by /u/allen108108
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[D] Questions on general research practices

Hi everyone,

I have a few questions on research practices that are generally followed but rarely mentioned in papers.

  1. Let’s say I have a train-dev-test split. After finding the best hyperparameters on dev set, should I retrain the model on train+dev set before evaluating it on the test set? Some discussions say yes, others say it depends on you and how much data you have and some say no.
  2. Let’s say I’m showcasing results on multiple datasets. Can one change the hyperparameters (learning rate, batch size, etc) from one dataset to another? More importantly, can I change, let’s say, number of units in a layer without adding more layers? Would this count as an architectural change?
  3. If yes, how would answer to above question change if the same is done within the dataset itself containing multiple parts?
  4. Are we allowed to change a publically available dataset? For example, removing outliers for a regression problem?

submitted by /u/manrajsinghgrover
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[R] Noise Regularization for Conditional Density Estimation

In neural network-based conditional density estimation (CDE), classic regularization approaches in the parameter space are mostly ineffective. To address this issue, we develop a model-agnostic noise regularization method for CDE that adds random perturbations to the data during training. We demonstrate that the proposed approach corresponds to a smoothness regularization, we prove its asymptotic consistency and show across 7 datasets and 3 CDE models that this works well. Result: makes neural network-based CDE the preferable method over previous non- and semi-parametric approaches, even when training data is scarce!

Paper: https://arxiv.org/abs/1907.08982
Code: https://github.com/freelunchtheorem/Conditional_Density_Estimation

submitted by /u/whiletrue2
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