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]>
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
>>>
>>
>>
