Good to know this method. Thanks a lot.
在 2016年7月6日星期三 UTC+9上午1:45:21，Cedric St-Jean写道： > > In Julia, if speed isn't too important, this gives the same results: > > a, b = [-1,-2,-3], [-3,-4,-5,-2] > inter = intersect(a, b) > (Int[findfirst(a, x) for x in inter], Int[findfirst(b, x) for x in inter]) > > And it should be a good deal faster than the MATLABism. Other functions > you might find useful: ind2sub, div (integer division) > > On Tue, Jul 5, 2016 at 12:20 PM, siyu song <[email protected] > <javascript:>> wrote: > >> Thanks, Fred, for your answer. But in fact I want to know the index of >> the common elements of two integer vectors(Elements are all different in >> each vectors). >> For example, v1 = [1,2,3] and v2[3,4,5,2]. So the answer should be >> common_index1 = [2,3], common_index2 = [1,4]. >> I use a function as >> function find_common(a,b) >> a = reshape(a,length(a),1); >> b = reshape(b,1,length(b)); >> la = length(a); >> lb = length(b); >> a = a[:,ones(1,lb)]; >> b = b[ones(la,1),:]; >> comab = find(x->x==true,a .== b); >> comab = comab.'; >> coma = mod(comab+la-1,la)+1; >> comb = floor(Int64,(comab+la-1)/la); >> return coma,comb; >> end >> >> So coma and comb is exactly what I want. In matlab this is easy to do. >> But with julia, I haven't thought of a clever answer yet. >> In matlab we can simply get coma and comb by [coma, comb] = find(a==b). >> >> 在 2016年7月5日星期二 UTC+9下午7:02:34，Fred写道： >> >>> julia> a=[1,3,5,7] >>> 4-element Array{Int64,1}: >>> 1 >>> 3 >>> 5 >>> 7 >>> >>> >>> julia> b=[2,3,5,6,7] >>> 5-element Array{Int64,1}: >>> 2 >>> 3 >>> 5 >>> 6 >>> 7 >>> >>> >>> julia> intersect(a,b) >>> 3-element Array{Int64,1}: >>> 3 >>> 5 >>> 7 >>> >>> >>> julia> union(a,b) >>> 6-element Array{Int64,1}: >>> 1 >>> 3 >>> 5 >>> 7 >>> 2 >>> 6 >>> >>> >>> >>> Le lundi 4 juillet 2016 04:18:10 UTC+2, siyu song a écrit : >>>> >>>> But intersect doesn't tell us the index of the elements in the >>>> matrix(array), I think. >>>> >>> >
