tensorflow / tensorflow/tensorboard

Projector point isolation : Cosine distance change and explained variance decrease

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plugin:projector theme:usability type:docs
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Description

Hello,
This issue is a request for an explaination about two points in Tensorboard's projector :

1 - Cosine distance changes when isolating a selection of points

Cosine distance seems to change when zooming on points. The right side column showing the nearest neighours has the mention 'in the original space'. I think I'm not the only one who also interpreted it as 'the cosine distance is also calculated in the original space', so I think it should be mentioned that it is not the case. The cosine distance seems to have been mapped from it's original interval to an interval somewhat close to [0, 2], but I couldn't find the formula for this change anywhere.
To sum it up:

  • The change occuring in the formula should be mentioned and documented
  • We should have a button to enable/disable this modified cosine distance
2 - PCA displays an explained variance of 100.0%, but it decreases when isolating points

Initial PCA with 100% explained variance shows a superposition of points with a cosine distance value of 0.000. When selecting and isolating these points, the superposition is no more, and the explained variance goes down to 92.6%. The superposed points are 20 in a 450 points representation, and there are many of such superposition cases in the same embedding (hence the fact that 100% variance explained is a bit shady.
Here is a link to my Tensorboard files folder.
An example of the case of superposition can be found in the embedding Embedddings/t_embedding if you look for the point labeled technicien assurance qualité.

Thank you for your time, and pardon my mistakes if I submitted this first issue in the wrong format.


Tensorboard version : 1.8.0
Tensorflow version: 1.6.0
Python Version : 3.6
OS : Windows 10

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start in TensorBoard's Projector with the supplied embedding and reproduce the cosine-distance and PCA explained-variance changes when points are isolated. Compare the initial view with the isolated selection, then document the distance mapping and explain the variance change; clarify whether a control for the modified distance is still required.

Written by the indexing model from the issue text.

Assessment

Tech stack
typescript
Domain
data-visualization, frontend
Issue type
Documentation
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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