How to Obtain Complete List of Properties

Question

I am working with Matrix Market matrices in Mathematica (specifically GEMAT12), and I saw from other posts that you call properties of a variable exemplified below:

A = Import["gemat12.mtx"];
A["Density"]
A["Dimensions"]

With the following output:

0.00136011
{4929, 4929}

So my question: How can I list all available properties of my variable A?

Answer 1

Importing "MTX" returns a SparseArray, so you can do A["Properties"]. You don't need to manually unzip your file to have access to the "MTX" data.

Import[
    "https://math.nist.gov/pub/MatrixMarket2/Harwell-Boeing/gemat/gemat12.mtx.gz"
    , {"GZIP", "MTX" }
]["Properties"] 

(* {AdjacencyLists,BandWidth,ColumnIndices,Density,ExplicitLength,ExplicitPositions,ExplicitValues,ImplicitValue,RowPointers,ReplaceValues} *) 

Also of interest

Import[
    "https://math.nist.gov/pub/MatrixMarket2/Harwell-Boeing/gemat/gemat12.mtx.gz"
    , {"GZIP", "MTX" , "Elements"}
]  

(* {Comments, Data, Graphics, MatrixStructure, Summary} *)