Many thanks, these are very helpful! Yes, the two vectors are going to be
of the same type. The StructsOfArrays package is interesting too, as let's
say you have a construction like this:
*arr = StructOfArrays(Pair{Float64, Float64}, 100)*
You can go ahead, and populate this as you need. If you need all the
firsts or seconds of the pairs, you can access the object's array param
(arr.arrays), and all the firsts are in the first array, and all the
seconds are in the second array. I noticed that at a certain size, the
sort algo must change, and I needed to override the resize! method for the
StructOfArrays type. I will compare the speed vs some of these other
options.
Thanks!!
On Monday, March 7, 2016 at 6:13:22 PM UTC-5, tshort wrote:
>
> There are several options to "keep things together", particularly with
> vectors of the same type:
>
> - DataFrame columns -- watch how you use columns to keep type stability
>
> - Nx2 Array
>
> - Nx2 NamedArray:
> https://github.com/davidavdav/NamedArrays.jl
>
> - AxisArrays:
> https://github.com/mbauman/AxisArrays.jl
>
>
> On Mon, Mar 7, 2016 at 5:11 PM, Christopher Alexander <[email protected]
> <javascript:>> wrote:
>
>> Yea, I was thinking about two different vectors, but then if I did any
>> sorting, the value vector and weight vector would be out-of-sync. I'll
>> check out this StructsOfArrays package
>>
>> Thanks!
>>
>> Chris
>>
>> On Monday, March 7, 2016 at 5:03:14 PM UTC-5, tshort wrote:
>>>
>>> It depends on what "various weighted statistical calculations" involves.
>>> I'd start with two vectors, `x` and `w`. If you really need them to be
>>> coupled tightly, you could define an immutable type to hold the value and
>>> the weight, but the two separate vectors can be faster for some operations.
>>> Also, see:
>>>
>>> https://github.com/simonster/StructsOfArrays.jl
>>>
>>> On Mon, Mar 7, 2016 at 4:50 PM, Christopher Alexander <[email protected]
>>> > wrote:
>>>
>>>> Hello all, I need to create a structure where I keep track of pairs of
>>>> value => weight so that I can do various weighted statistical calculations.
>>>>
>>>> I know that StatsBase has a weights vector, which I plan on using, but
>>>> the way that is set up is that it is disassociated from each of the values
>>>> to which the weights are to be applied.
>>>>
>>>> I need the mapping that "Pair" provides, but I've noticed that there is
>>>> no easy way, if I have an array of pairs, to grab all the first values or
>>>> all the second values (like you can do with a dict in grabbing keys or
>>>> values).
>>>>
>>>> I've tried to do something like map(first, my_array_of_pairs), but this
>>>> is about 10x slower than if you have a dictionary of value => weight and
>>>> just asked for the keys. I actually tried to use a dict at first, but ran
>>>> into issues with duplicate values (they were overwriting each other
>>>> because
>>>> the value was the key).
>>>>
>>>> Any suggestions, or any better way to manipulate an array of Pairs?
>>>>
>>>> Thanks!
>>>>
>>>> Chris
>>>>
>>>
>>>
>
