Use `enumerate`:
julia> a = [1,3,5,8]
julia> b = [1,2,5,7]
julia> intersect(enumerate(a), enumerate(b))
2-element Array{Tuple{Int64,Int64},1}:
(1,1)
(3,5)
On July 5, 2016 at 13:20:15, siyu song ([email protected]) wrote:
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.
>>>>
>>>
>
