Re: [julia-users] Composite Type Array

[maxent219]

Thanks alot Cameron & Jared.

This makes much more sense now & the composite type seems more usable. I 
had erroneous & conflicting expectations of how I would interact with the 
events data structure after preallocating it. 

I'm going to try it out & see how it fits into a larger scale project. 

On Friday, July 22, 2016 at 3:19:26 PM UTC-4, Cameron McBride wrote:
>
>
> On Fri, Jul 22, 2016 at 3:09 PM, Cameron McBride  > wrote:
>
>> julia> function get_event(v::Vector{ExampleEvent}, i)
>>  n = length(v)
>>  if i > n
>>for j in n:i
>>push!(v, ExampleEvent("",0,0,0,0,0,0)) # default values
>>end
>>  end
>>  v[i]
>>end
>>
>
> haha, that creates one extra element (ExampleEvent row) on the first pass. 
> Whoops. Here is a quick fix. Likely better ways to do all this, just 
> kicking it further.
>
> julia> function get_event(v::Vector{ExampleEvent}, i)
>  n = length(v)
>  if i > n
>i1 = n > 0 ? n : 1
>for x in i1:i
>push!(v, ExampleEvent("",0,0,0,0,0,0)) # default values
>end
>  end
>  v[i]
>end
>
> Cameron
>

Re: [julia-users] Composite Type Array

[Cameron McBride]

On Fri, Jul 22, 2016 at 3:09 PM, Cameron McBride 
wrote:

> julia> function get_event(v::Vector{ExampleEvent}, i)
>  n = length(v)
>  if i > n
>for j in n:i
>push!(v, ExampleEvent("",0,0,0,0,0,0)) # default values
>end
>  end
>  v[i]
>end
>

haha, that creates one extra element (ExampleEvent row) on the first pass.
Whoops. Here is a quick fix. Likely better ways to do all this, just
kicking it further.

julia> function get_event(v::Vector{ExampleEvent}, i)
 n = length(v)
 if i > n
   i1 = n > 0 ? n : 1
   for x in i1:i
   push!(v, ExampleEvent("",0,0,0,0,0,0)) # default values
   end
 end
 v[i]
   end

Cameron

Re: [julia-users] Composite Type Array

[Jared Crean]

I think what you are looking for is a constructor for your new type that 
uses incomplete initialization


type ExampleEvent

fld1::ASCIIString
fld2::Int16
fld3::Int64
fld4::Int64
fld5::Int64
fld6::Int64
fld7::Int64

function ExampleEvent(fld1, fld2)
  obj = new()  # create new object, without assigning values to 
fields
  obj.fld1 = fld1
  obj.fld2 = fld2

  return obj
end
end

  Now you can use this constructor when assigning elements to the array

   events = Vector{ExampleEvent}(1000)
   for i=1:10
  events[i] = ExampleEvent("abc", i)
   end
   events[5].fld3 = 7  # assign to previously undefined field

   Note that you will get an error if you try to read a value from a field 
that hasn't been set yet:

   event = ExampleEvent("abc", 2)
   y = event.fld3  # error, accessing undefined reference

  Best,
Jared Crean

On Friday, July 22, 2016 at 2:38:27 PM UTC-4, maxe...@gmail.com wrote:
>
>
> Thanks Cameron. 
>
> What I wanted to do was assign values to fields but the example you posted 
> requires me to pass values to all fields in my type. 
>
> If I do: events[1] = ExampleEvent("asdf",123), julia throws an error since 
> I need to pass values to ALL my type's fields. I don't always have to use 
> all fields & sometimes do not have data for all fields, thus I don't want 
> to be obligated to pass even null values to them since it is 
> verbose/excessive. Nor do I want to rewrite constructors for all fields 
> since I already have named fields for sake of programming ease. 
>
> See what I mean? 
>
> Moreover, let's say I've filled 10 elements of my 1000 element array & a 
> few milliseconds later I get a value for element 5, fld3. How do I index 
> into element 5 of the events Vector & ONLY set fld3? 
>
> Yes I've seen push! & looks good but I'm pretty religious about 
> precallocating in any lang even if it is much larger than needed since 
> processing these datasets require as much efficiency as possible.
>
> I think more intuitive Composite Type Arrays for morons like me would make 
> Juila much easier to work with since I've seen a fair amount of 
> uncertainty/confusion from people having similar conceptual use cases. I 
> know I'm thinking from a perspective of other language(s) but some language 
> constructs are there because they work & make a programmer's life easier. 
> Is there an easy way to set field value(s) whenever I get them? 
>
> On Friday, July 22, 2016 at 2:01:41 PM UTC-4, Cameron McBride wrote:
>>
>> Your ExampleEvent is completely analagous to a C-like struct. With 
>> Stefan's bit, you now have a single dimension array of ExampleEvent type 
>> (hence ndims(events) is 1). 
>>
>> You can do this:
>> julia> events[1] = ExampleEvent("asdf",2,3,4,5,6,7)
>> ExampleEvent("asdf",2,3,4,5,6,7)
>>
>> And if you have more, you can do this: 
>> julia> push!(events, ExampleEvent("ghjk", 2,3,4,5,6,7))
>> 1001-element Array{ExampleEvent,1}:
>> ExampleEvent("asdf",2,3,4,5,6,7)
>>  #undef
>>⋮
>>  #undef
>> ExampleEvent("ghjk",2,3,4,5,6,7)
>>
>> Cameron
>>
>> On Fri, Jul 22, 2016 at 1:48 PM,  wrote:
>>
>>> Thanks Stefan!
>>>
>>> I thought it would be like declaring a struct array in c/c++ i.e. 
>>> something like ExampleEvent events[2][1000]; Then set each field in the 
>>> events array as I encounter the required value in my algo: e.g. 
>>> events[1][1].fld1 = "ABC";  events[1][1].fld2 = 123;   etc
>>>
>>> How do I access elements in the events Vector since ndims(events) = 1? I 
>>> don't see anything in the docs about indexing into a preallocated Vector 
>>> data structure. I see methods like push! splice! etc but not anything that 
>>> will let me use the elements of my preallocation on the fly. 
>>>
>>>
>>> On Thursday, July 21, 2016 at 3:21:54 PM UTC-4, Stefan Karpinski wrote:

 It's a little unclear what you want to do that you can't figure out how 
 to accomplish. You can allocate an uninitialized vector of ExampleEvent 
 objects:

 julia> type ExampleEvent
fld1::ASCIIString
fld2::Int16
fld3::Int64
fld4::Int64
fld5::Int64
fld6::Int64
fld7::Int64
end

 julia> events = Vector{ExampleEvent}(1000)
 1000-element Array{ExampleEvent,1}:
  #undef
  #undef
  #undef
⋮
  #undef
  #undef
  #undef




 On Thu, Jul 21, 2016 at 2:51 PM,  wrote:

>
> Hi 
>
> I was working on processing large data sets & historically I've used 
> structs in C++ & other languages for this type of task. I attempted to 
> use 
> a Composite Type in Julia & preallocate a large array before filling it 
> w/values as my algo processes the data. 
>
> My example was:
>
> type 

Re: [julia-users] Composite Type Array

[maxent219]

Thanks Cameron. 

What I wanted to do was assign values to fields but the example you posted 
requires me to pass values to all fields in my type. 

If I do: events[1] = ExampleEvent("asdf",123), julia throws an error since 
I need to pass values to ALL my type's fields. I don't always have to use 
all fields & sometimes do not have data for all fields, thus I don't want 
to be obligated to pass even null values to them since it is 
verbose/excessive. Nor do I want to rewrite constructors for all fields 
since I already have named fields for sake of programming ease. 

See what I mean? 

Moreover, let's say I've filled 10 elements of my 1000 element array & a 
few milliseconds later I get a value for element 5, fld3. How do I index 
into element 5 of the events Vector & ONLY set fld3? 

Yes I've seen push! & looks good but I'm pretty religious about 
precallocating in any lang even if it is much larger than needed since 
processing these datasets require as much efficiency as possible.

I think more intuitive Composite Type Arrays for morons like me would make 
Juila much easier to work with since I've seen a fair amount of 
uncertainty/confusion from people having similar conceptual use cases. I 
know I'm thinking from a perspective of other language(s) but some language 
constructs are there because they work & make a programmer's life easier. 
Is there an easy way to set field value(s) whenever I get them? 

On Friday, July 22, 2016 at 2:01:41 PM UTC-4, Cameron McBride wrote:
>
> Your ExampleEvent is completely analagous to a C-like struct. With 
> Stefan's bit, you now have a single dimension array of ExampleEvent type 
> (hence ndims(events) is 1). 
>
> You can do this:
> julia> events[1] = ExampleEvent("asdf",2,3,4,5,6,7)
> ExampleEvent("asdf",2,3,4,5,6,7)
>
> And if you have more, you can do this: 
> julia> push!(events, ExampleEvent("ghjk", 2,3,4,5,6,7))
> 1001-element Array{ExampleEvent,1}:
> ExampleEvent("asdf",2,3,4,5,6,7)
>  #undef
>⋮
>  #undef
> ExampleEvent("ghjk",2,3,4,5,6,7)
>
> Cameron
>
> On Fri, Jul 22, 2016 at 1:48 PM,  wrote:
>
>> Thanks Stefan!
>>
>> I thought it would be like declaring a struct array in c/c++ i.e. 
>> something like ExampleEvent events[2][1000]; Then set each field in the 
>> events array as I encounter the required value in my algo: e.g. 
>> events[1][1].fld1 = "ABC";  events[1][1].fld2 = 123;   etc
>>
>> How do I access elements in the events Vector since ndims(events) = 1? I 
>> don't see anything in the docs about indexing into a preallocated Vector 
>> data structure. I see methods like push! splice! etc but not anything that 
>> will let me use the elements of my preallocation on the fly. 
>>
>>
>> On Thursday, July 21, 2016 at 3:21:54 PM UTC-4, Stefan Karpinski wrote:
>>>
>>> It's a little unclear what you want to do that you can't figure out how 
>>> to accomplish. You can allocate an uninitialized vector of ExampleEvent 
>>> objects:
>>>
>>> julia> type ExampleEvent
>>>fld1::ASCIIString
>>>fld2::Int16
>>>fld3::Int64
>>>fld4::Int64
>>>fld5::Int64
>>>fld6::Int64
>>>fld7::Int64
>>>end
>>>
>>> julia> events = Vector{ExampleEvent}(1000)
>>> 1000-element Array{ExampleEvent,1}:
>>>  #undef
>>>  #undef
>>>  #undef
>>>⋮
>>>  #undef
>>>  #undef
>>>  #undef
>>>
>>>
>>>
>>>
>>> On Thu, Jul 21, 2016 at 2:51 PM,  wrote:
>>>

 Hi 

 I was working on processing large data sets & historically I've used 
 structs in C++ & other languages for this type of task. I attempted to use 
 a Composite Type in Julia & preallocate a large array before filling it 
 w/values as my algo processes the data. 

 My example was:

 type ExampleEvent

 fld1::ASCIIString
 fld2::Int16
 fld3::Int64
 fld4::Int64
 fld5::Int64
 fld6::Int64
 fld7::Int64

 end

 I googled around & from what I found, & all the docs examples I tried 
 out, there isn't an obvious way to declare an array of composite type 
 without having to do some work arounds. 

 I liked the language in several other respects but it seems to be 
 missing helpful tools to make the programmer's life easy. Am I missing 
 something? If not, why is a data structure like this not easily available? 

 thanks in advance

 best,
 A 

>>>
>>>
>

Re: [julia-users] Composite Type Array

[maxent219]

Thanks Stefan!

I thought it would be like declaring a struct array in c/c++ i.e. something 
like ExampleEvent events[2][1000]; Then set each field in the events array 
as I encounter the required value in my algo: e.g. events[1][1].fld1 = 
"ABC";  events[1][1].fld2 = 123;   etc

How do I access elements in the events Vector since ndims(events) = 1? I 
don't see anything in the docs about indexing into a preallocated Vector 
data structure. I see methods like push! splice! etc but not anything that 
will let me use the elements of my preallocation on the fly. 


On Thursday, July 21, 2016 at 3:21:54 PM UTC-4, Stefan Karpinski wrote:
>
> It's a little unclear what you want to do that you can't figure out how to 
> accomplish. You can allocate an uninitialized vector of ExampleEvent 
> objects:
>
> julia> type ExampleEvent
>fld1::ASCIIString
>fld2::Int16
>fld3::Int64
>fld4::Int64
>fld5::Int64
>fld6::Int64
>fld7::Int64
>end
>
> julia> events = Vector{ExampleEvent}(1000)
> 1000-element Array{ExampleEvent,1}:
>  #undef
>  #undef
>  #undef
>⋮
>  #undef
>  #undef
>  #undef
>
>
>
>
> On Thu, Jul 21, 2016 at 2:51 PM,  wrote:
>
>>
>> Hi 
>>
>> I was working on processing large data sets & historically I've used 
>> structs in C++ & other languages for this type of task. I attempted to use 
>> a Composite Type in Julia & preallocate a large array before filling it 
>> w/values as my algo processes the data. 
>>
>> My example was:
>>
>> type ExampleEvent
>>
>> fld1::ASCIIString
>> fld2::Int16
>> fld3::Int64
>> fld4::Int64
>> fld5::Int64
>> fld6::Int64
>> fld7::Int64
>>
>> end
>>
>> I googled around & from what I found, & all the docs examples I tried 
>> out, there isn't an obvious way to declare an array of composite type 
>> without having to do some work arounds. 
>>
>> I liked the language in several other respects but it seems to be missing 
>> helpful tools to make the programmer's life easy. Am I missing something? 
>> If not, why is a data structure like this not easily available? 
>>
>> thanks in advance
>>
>> best,
>> A 
>>
>
>

Re: [julia-users] Composite Type Array

[Stefan Karpinski]

It's a little unclear what you want to do that you can't figure out how to
accomplish. You can allocate an uninitialized vector of ExampleEvent
objects:

julia> type ExampleEvent
   fld1::ASCIIString
   fld2::Int16
   fld3::Int64
   fld4::Int64
   fld5::Int64
   fld6::Int64
   fld7::Int64
   end

julia> events = Vector{ExampleEvent}(1000)
1000-element Array{ExampleEvent,1}:
 #undef
 #undef
 #undef
   ⋮
 #undef
 #undef
 #undef




On Thu, Jul 21, 2016 at 2:51 PM,  wrote:

>
> Hi
>
> I was working on processing large data sets & historically I've used
> structs in C++ & other languages for this type of task. I attempted to use
> a Composite Type in Julia & preallocate a large array before filling it
> w/values as my algo processes the data.
>
> My example was:
>
> type ExampleEvent
>
> fld1::ASCIIString
> fld2::Int16
> fld3::Int64
> fld4::Int64
> fld5::Int64
> fld6::Int64
> fld7::Int64
>
> end
>
> I googled around & from what I found, & all the docs examples I tried out,
> there isn't an obvious way to declare an array of composite type without
> having to do some work arounds.
>
> I liked the language in several other respects but it seems to be missing
> helpful tools to make the programmer's life easy. Am I missing something?
> If not, why is a data structure like this not easily available?
>
> thanks in advance
>
> best,
> A
>

[julia-users] Composite Type Array

[maxent219]

Hi 

I was working on processing large data sets & historically I've used 
structs in C++ & other languages for this type of task. I attempted to use 
a Composite Type in Julia & preallocate a large array before filling it 
w/values as my algo processes the data. 

My example was:

type ExampleEvent

fld1::ASCIIString
fld2::Int16
fld3::Int64
fld4::Int64
fld5::Int64
fld6::Int64
fld7::Int64

end

I googled around & from what I found, & all the docs examples I tried out, 
there isn't an obvious way to declare an array of composite type without 
having to do some work arounds. 

I liked the language in several other respects but it seems to be missing 
helpful tools to make the programmer's life easy. Am I missing something? 
If not, why is a data structure like this not easily available? 

thanks in advance

best,
A