Thanks for the explanation!! That's exactly what I need at the moment,
though I clearly know that unpredictable return type could be dangerous.
Many thanks.
On Sunday, May 15, 2016 at 9:07:12 PM UTC+1, Kristoffer Carlsson wrote:
>
> 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, [email protected] 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 [email protected] 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!
>>>
>>>
