Allow for quantile to operate over an entire Matrix

[this-josh]

As discussed here if you pass a matrix to quantile you get an error

julia> quantile(reshape(collect(1:100), (10, 10)), [0.00, 0.25, 0.50, 0.75, 1.00])
ERROR: MethodError: no method matching quantile!(::Matrix{Int64}, ::Vector{Float64}; sorted=false, alpha=1.0, beta=1.0)
Closest candidates are:
  quantile!(::AbstractArray, ::AbstractVector, ::AbstractArray; sorted, alpha, beta) at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/Statistics/src/Statistics.jl:936
  quantile!(::AbstractVector, ::Union{Tuple{Vararg{Real}}, AbstractArray}; sorted, alpha, beta) at /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/Statistics/src/Statistics.jl:953
Stacktrace:
 [1] quantile(itr::Matrix{Int64}, p::Vector{Float64}; sorted::Bool, alpha::Float64, beta::Float64)
   @ Statistics /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/Statistics/src/Statistics.jl:1070
 [2] quantile(itr::Matrix{Int64}, p::Vector{Float64})
   @ Statistics /Applications/Julia-1.7.app/Contents/Resources/julia/share/julia/stdlib/v1.7/Statistics/src/Statistics.jl:1070
 [3] top-level scope
   @ REPL[2]:1

I made a small change which vectorises a matrix and provides the quantile for the whole matrix.

julia> quantile(reshape(collect(1:100), (10, 10)), [0.00, 0.25, 0.50, 0.75, 1.00])
5-element Vector{Float64}:
   1.0
  25.75
  50.5
  75.25
 100.0

This change was originally made in StatsBase with PR 773.

[codecov]

Codecov Report

Merging #108 (4c8d6f1) into master (61a021b) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #108      +/-   ##
==========================================
+ Coverage   96.91%   96.93%   +0.01%     
==========================================
  Files           1        1              
  Lines         422      424       +2     
==========================================
+ Hits          409      411       +2     
  Misses         13       13              

Impacted Files	Coverage Δ
src/Statistics.jl	96.93% <100.00%> (+0.01%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 61a021b...4c8d6f1. Read the comment docs.

[nalimilan]

Thanks!

[nalimilan]

Why did you remove the quantile! method? Isn't it need for quantile! to work on matrices?

[this-josh]

Sorry your question about the in-place test confused me. Anyways, I think I've implemented the changes you requested.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (master@61a021b). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master     #108   +/-   ##
=========================================
  Coverage          ?   96.93%           
=========================================
  Files             ?        1           
  Lines             ?      424           
  Branches          ?        0           
=========================================
  Hits              ?      411           
  Misses            ?       13           
  Partials          ?        0           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 61a021b...847dff4. Read the comment docs.

[nalimilan]

Thanks, and sorry for the delay!