Hi
In Python, I am able to select values like this:
>>> a = np.matrix([[-1,2],[3,-4]])
>>> y = np.matrix([1,0])
>>> a[range(2),y]
matrix([[2, 3]])
>>>
Is there any equivalent in Julia or using a loop is the only way?
julia> a
2x2 Array{Int64,2}:
-1 2
3 -4
julia> y
1x2 Array{Int64,2}:
1 2
julia> a[:, y]
ERROR: MethodError: `index_shape_dim` has no method matching
index_shape_dim(::Array{Int64,2}, ::Int64, ::Array{Int64,2})
You might have used a 2d row vector where a 1d column vector was required.
Note the difference between 1d column vector [1,2,3] and 2d row vector [1 2
3].
You can convert to a column vector with the vec() function.
Closest candidates are:
index_shape_dim(::Any, ::Any, ::Real...)
index_shape_dim(::Any, ::Any, ::Colon)
index_shape_dim(::Any, ::Any, ::Colon, ::Any, ::Any...)
...
in getindex at abstractarray.jl:488
julia> a[:, y[]]
2-element Array{Int64,1}:
-1
3
julia> a[:, y[:]]
2x2 Array{Int64,2}:
-1 2
3 -4
julia>
