# Function does not run correctly (Linear and Cartesian Indices)

**URL:** <https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294>\
**Category:** New to Julia\
**Tags:** question\
**Created:** [June 14, 2019, 7:27am UTC](https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294 "2019-06-14T07:27:18Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Amin\_Yahyaabadi](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/amin_yahyaabadi/32/9826_2.png) [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Post date:** [June 14, 2019, 7:27am UTC](https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294/1 "2019-06-14T07:27:18Z")

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Basically, I have a test function which I call from a main script in Atom.  
However, the function returns NaN array as mA. Whereas, if I copy paste and run parts of the code inside REPL it runs without any issue. Where is the problem?  
I even tried running test() function as a script (not a function) and I have the same problem.

```julia
function test()

    matrixSize=30;
    mX = randn(matrixSize, matrixSize);

    # Assuming Samples are slong Columns (Rows are features)
    numClusters = Int64( max( round(matrixSize / 100), 1 ) ); # % max between 1 and round(...)
    numIterations = 10;

    # http://stackoverflow.com/questions/36047516/julia-generating-unique-random-integer-array
    mA = mX[:, randperm(matrixSize)[1:numClusters]] ; #<! Cluster Centroids

    for ii = 1:numIterations

        vMinDist, mClusterId = findmin( transpose(sum(mA .^ 2, dims=1)) .- (2 .* transpose(mA)* mX), dims=1); #<! Is there a `~` equivalent in Julia?
        vClusterId=dropdims(mClusterId, dims=1); # to be able to access it later

        for jj = 1:numClusters
            mA[:, jj] = mean( mX[:, vClusterId .== jj], dims=2 );
        end
    end

    mA = mA[:, 1] .+ transpose(mA[:, end]);

    return mA
end

```

I call the function from a main script like this:

```julia
using Statistics
using LinearAlgebra
using Random # for randperm
include("test.jl");
mA=test();

```

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<div class="post-metadata">

**Author:** ![kdyrhage](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kdyrhage/32/2326_2.png) [@kdyrhage](https://discourse.julialang.org/u/kdyrhage)\
**Post date:** [June 14, 2019, 7:40am UTC](https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294/2 "2019-06-14T07:40:31Z")

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I get the same result (NaNs) in the REPL.

---

<div class="post-metadata">

**Author:** ![JeffreySarnoff](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeffreysarnoff/32/1980_2.png) [@JeffreySarnoff](https://discourse.julialang.org/u/JeffreySarnoff)\
**Post date:** [June 14, 2019, 8:01am UTC](https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294/3 "2019-06-14T08:01:21Z")

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The problem is with `vClusterId` and this line :  
`mA[:, jj] = mean( mX[:, vClusterId .== jj], dims=2 );`

```julia
julia> typeof(vClusterId)
Array{CartesianIndex{2},1}
julia> typeof(jj)
Int64
julia> jj=1; any(vClusterId .== jj)
false

```

so you are taking the `mean` of 0 values

```julia
julia> mean(Int[])
NaN

```

and so you set `mA` to be `NaNs`

change `vClusterId=dropdims(mClusterId, dims=1);`  
to `vClusterId = LinearIndices(dropdims(mClusterId, dims=1))`;  
and your test function will operate.

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<div class="post-metadata">

**Author:** ![Amin\_Yahyaabadi](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/amin_yahyaabadi/32/9826_2.png) [@Amin\_Yahyaabadi](https://discourse.julialang.org/u/Amin_Yahyaabadi)\
**Post date:** [June 14, 2019, 4:11pm UTC](https://discourse.julialang.org/t/function-does-not-run-correctly-linear-and-cartesian-indices/25294/4 "2019-06-14T16:11:13Z")

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Thank you for your answer.  
The original code was in Julia 0.5 and it worked fine there, the code was like

```julia
   for ii = 1:numIterations

        vMinDist, mClusterId(:) = findmin( transpose(sum(mA .^ 2, dims=1)) .- (2 .* transpose(mA)* mX), dims=1); 

        for jj = 1:numClusters
            mA[:, jj] = mean( mX[:, vClusterId .== jj], dims=2 );
        end
    end

```

In Julia 1.1 I got an error, I thought it is because of dropdims. I am not familiar with the changes that has happend since that time. (diverging from MATLAB language)