It is possible but seems like something undesirable because you then don't
know if an Array{T,1} or Array{T,2} will be returned by the function. This
is something Julia people like to call "type instability" when the type of
your returned variables depend not only on the type of the arguments to the
function.
If you really want this, then this is an example:
function maybevec(A::AbstractMatrix)
if size(A, 2) == 1 || size(A, 1) == 1
return vec(A)
else
return A
end
end
julia> maybevec(rand(5,5))
5×5 Array{Float64,2}:
0.542099 0.901245 0.267711 0.260192 0.395683
0.361152 0.373492 0.231736 0.259319 0.933759
0.307834 0.460153 0.157018 0.712722 0.194619
0.869251 0.947844 0.5374 0.715395 0.67132
0.928848 0.642071 0.948639 0.693701 0.562648
julia> maybevec(rand(5,1))
5-element Array{Float64,1}:
0.579539
0.012443
0.307975
0.742628
0.997113
On Sunday, May 15, 2016 at 9:17:27 PM UTC+2, chobb...@gmail.com wrote:
>
> Thanks for the pointer for reshape.
>
> Sorry that I failed to make my question clear enough. In fact, I wonder if
> there is a function which can _automatically_ recast a single-column
> Array{T,2} to an Array{T,1} and do nothing if this Array{T,2} has multiple
> rows.
>
>
>
>
>
> On Sunday, May 15, 2016 at 6:41:51 PM UTC+1, Tim Holy wrote:
>>
>> See reshape and vec.
>>
>> Best,
>> --Tim
>>
>> On Sunday, May 15, 2016 09:00:33 AM chobb...@gmail.com wrote:
>> > Here is rookie question, which I have tried to find a similar question
>> and
>> > answer in the history of this group, but failed. Please bear me.
>> >
>> > Since Julia distinguishes between Array{Float64,1} and
>> Array{Float64,2},
>> > even there is only one column in an Array{Float64,2}. Therefore, the
>> type
>> > of rand(5) and rand(5,1) are not same.
>> >
>> > julia> x = rand(5)
>> > 5-element Array{Float64,1}:
>> > 0.183247
>> > 0.480208
>> > 0.623144
>> > 0.342792
>> > 0.0400695
>> >
>> > julia> y = rand(5, 1)
>> > 5x1 Array{Float64,2}:
>> > 0.553224
>> > 0.0061835
>> > 0.762059
>> > 0.643796
>> > 0.655135
>> >
>> >
>> > Is there any way that I can upgrade x about to become an
>> Array{Float64,2}?
>> > And is there a way to downgrade y to become an Array{Float64,1}, when
>> it
>> > has only one column?
>> >
>> > In case that there is a similar discussion before, a link to the
>> previous
>> > thread is good enough and appreciated!
>> >
>> > Thanks!
>>
>>
