# Trying Julia

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In my previous post I tried building Williams designs in R. Since that code was running a bit slow, this was an ideal test for Julia. Big enough to be at least slightly realistic, small enough that it is doable.**Wiekvoet**, and kindly contributed to R-bloggers]. (You can report issue about the content on this page here)Want to share your content on R-bloggers? click here if you have a blog, or here if you don't.

I am very impressed. Almost twenty fold speed increase, even though this was the best I could do in R, the most naive way possible in Julia.

R Julia Ratio

Double Williams design 4, 100 times 3.97 sec 0.212 sec 0.053

Williams design 5, 10 times 289.5 sec 18.54 sec 0.064

I’d surely love to use Julia more. For instance, if I could port some of the algorithm’s of Professor Ng Machine Learning class to Julia? I don’t think it is possible yet, but what is not, may come.

#### Julia code

macro timeit(ex,name,num)

quote

t0 = 0

for i=1:$num

t0 = t0 + @elapsed $ex

end

println(“julia,”, $name, “,”, t0)

#gc()

end

end

function gendesign(ncol)

nrow=ncol*2

desmat = zeros(Uint8,nrow,ncol)

desmat[1,1:ncol] = [1:ncol]

for i = [1:ncol]

desmat[2*i-1,1] = i

desmat[2*i,1]=i

end

carover = zeros(Uint8,ncol,ncol)

for i = 1:(ncol-1)

carover[i,i+1] = 1

end

count = 0

addpoint( desmat , carover,count)

end

function numzero(matin)

length(matin) – nnz(matin)

end

function first0(matin)

if numzero(matin)==0

return -1

end

nrow, ncol = size(matin)

for row = 1:nrow

for col = 1:ncol

if matin[row,col] == 0

return row, col

end

end

end

end

function addpoint(desmat,carover,count)

if nnz(desmat) == length(desmat)

count +=1

print(“x”)

return count

end

row,col = first0(desmat)

for i = [1:size(desmat,2)]

if numzero(desmat[row,:]-i) == 0

if numzero(desmat[:,col]-i) < 2

if carover[desmat[row,col-1],i] < 2

if (col !=2) | (desmat[row,1] != desmat[row-1,1]) | (desmat[row-1,col] < i)

desmat[row,col]=i

carover[desmat[row,col-1],i] +=1

count = addpoint(desmat,carover,count)

desmat[row,col]=0

carover[desmat[row,col-1],i] -=1

end

end

end

end

end

return count

end

@timeit gendesign(4) “design 4 ” 100

@timeit gendesign(5) “design 5 ” 10

#### Note

Both designs were created using the same script. If you ask an even number of design points using the odd algorithm, then this will work. You just get a design with double the rows, carry over balanced, every treatment equally often in each row and each column.To

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