My point was that if that loop you posted is run in global scope, it's likely to be slow.
http://docs.julialang.org/en/release-0.4/manual/performance-tips/ On Wed, Dec 2, 2015 at 11:04 AM, Rajn <rjngrj2...@gmail.com> wrote: > Stefan, > I have a function which loads the data structure, loads the actual data > file and defines frame numbers, determines PACKSIZE etc. > But to test the performance I did not use the function for but as in > global scope. > > Tom, I will look up your suggestion. > Thanks > > On Wednesday, December 2, 2015 at 12:56:48 AM UTC-5, Rajn wrote: >> >> I am reading a binary file with a structure. Matlab takes long and I >> wanted to run Julia for speed improvement. >> It reads camera frames, each with certain bytesize and each frame >> consisting of parameters of certain byte size and Type. >> >> frames: is declared Int64 and runs from 1:frames >> PACKSIZE is declared Int64 and is constant >> key_ind is Int16 and is a vector. This denotes the parameters which >> defines the frames. There are 200 but I am only interested in 3. >> Type declared Type as: 1x3 Array of Int16, Int16, Float64... >> Num as Int64 and 3x1 elements and each is 1. This says that there are >> only 1 elements of each Type in a frame. >> >> This is where I want to store the data... >> dCell = 3x1 Array{Any,2} of Array{Int16}(1xframes) >> Array{Int16}(1xframes) and Array{Float64}(1xframes) >> >> each camera frame is of PACKSIZE in bytes. >> >> To summarize I have declared the type of each variable before I start the >> read process. >> >> #Read and assemble the data structured as series of Int16,Int16,Float64... >> for j=1:length(frames); >> Pos = frames[j]*PACKSIZE ; >> for k=1:size(key_ind,1) >> seek(fid,Pos[k]); >> value = read(ifov_fid, Type[k][1],Num[k]); #Num[k] is all ones. >> dCell[k][:,j]=value; >> end >> end >> >> For 500,000 frames it takes as much time as Matlab. Not getting warnings >> or errors but would like to know how to improve the code for speed or >> efficiency. >> >> I am not familiar with binary read and was wondering if this is 'normal' >> and one cannot do any better? If I were to write this in C would it also >> take the same amount (maybe because of my sloppy code)? I should perhaps >> give details on the processor I use but because I am only comparing Matlab >> with Julia - and I am not doing any parallelization - I think that OS >> details are not important? >> In the Matlab code I am declaring few variables types but not being very >> careful as I am in with Julia. >> I am not reading the entire structure i.e., key_ind =1:3 of 200, each >> with different byte size. Therefore, I am not providing @time but if >> curious it is ~30-45 seconds for 500000 frames. The inner for-loop takes >> about ~0.00007 seconds. >> Thanks >> >> >>
