Implement Similarity network fusion

[shntnu]

http://www.nature.com/nmeth/journal/v11/n3/full/nmeth.2810.html

[cells2numbers]

I tested and used the implementation from Max Conway

https://github.com/maxconway/SNFtool/blob/master/R/SNF.R

Could it be added as an dependency?

[shntnu]

@cells2numbers sounds good! But have a look at http://r-pkgs.had.co.nz/description.html#dependencies to decide the level of the dependency.

[cells2numbers]

example vignette showing the usage of SNF can be found in cytominergallery, see cytomining/cytominergallery#43

[shntnu]

Will track in cytomining/cytominergallery#43