core-matrix

intended for specific discussion around core.matrix (usage and development) For general data work check out #data-science
2017-04-12T08:51:17.959545Z

Hi I check the channel occasionally but GitHub issues might be a better way to query (especially if it is likely to be a common issue where the answer may help others)

2017-04-12T09:36:38.457651Z

For you select example I get [[1 2 1] [3 4 3] [5 6 5]] which is what you expect?

2017-04-12T09:38:18.475099Z

index is a constructor function, for creating index instances. Some implementations may have custom index types, this lets you build them

2017-04-12T09:39:30.487652Z

index-seq gets a sequence of the above indices which cover the whole array. You might filter them if you wanted to access specific elements for example. Having said that, this is a bit of a specialised function so unless you really know why you need this there is probably a better / faster approach

jsa-aerial 2017-04-12T23:50:35.129043Z

Yes, I get the [[1 2 1] [3 4 3] [5 6 5]] which is not what I would expect. The expectation is that this is an example of 'integer indexing' ala' numpy or matlab, http://et.al. And there the expectation for this is the first vector selects the (in this case) rows and the second vector selects the elements in those rows. So, the expected return is [1 4 1]. This semantic seems rather more useful than the one select actually uses. I don't really see the point of the semantic it actually has.

jsa-aerial 2017-04-12T23:53:19.148851Z

Also, wrt to these index instances, what part of the api actually uses them? None of the obvious candidates select, slice, submatrix, ... seem to take these as legal input.