1.

2. Introduction

DEADLINE: end of March

2.1. Objectives:

• GET: To retrieve subset of data elements
• GET_SIZE: To interrogate the size of subset of data elements,

2.2. Assumptions:

• GET_SLICE type methods are not in the scope of the task (they are alternative ways to retrieve parts of the data elements) – although may be useful to add (independently of the deliverable) if straightforward to implement.
• Implementation in Python only, no plans for other languages
• In case of nested AoS, it is not allowed to specify set of indices for AoS ancestors
• IMPLEMENTATION IN NEW LL ONLY!!!!!

3.  

4. USE CASES:

1. During the partial GET, only the requested node is returned (and the structure below if the node is not a leaf), not the whole structure above: get (« magnetics.flux_loop(i).flux ») à flux(t) for index (i) of its parent
2. If the user specifies a set of indices for the parent, then the GET returns a reshaped leaf with an additional dimension (corresponding to the one of its parent). Reshaping is done while keeping time as the last dimension, to keep consistent with the IMAS DD rule (even if the reshaped leaf is not anymore a legal DD entity) :
   1. get (« magnetics.flux_loop(i1:i2).flux ») à flux(i1:i2, t)
   2. get (« equilibrium.time_slice(t1:t2).profiles_1d.q ») à q(:, t1:t2)
   3. In case of nested AoS, it is not allowed to specify set of indices for AoS ancestors. Only given values of AoS ancestors indices are handled : path/to/field/with/ancestorAoS(x:y)/field/AoS(n :m) is not managed by partial GET

4.1. Time issue in heterogeneous mode:

  Let's assume Aos is tuple {data, time}

• GET(/path/to/AoS/) - OK
• GET(/path/to/AoS/data)  
  •   Homogeneous mode: OK
  • Heterogeneous  mode:
    • If requesting for single index - OK
      
    • otherwise - ERROR
• GET(/path/to/AoS/time) 
  
  • Homogeneous mode: ids%time
  • Heterogeneous  mode: ERROR 
  
  

Example:

• get (« magnetics.flux_loop(i1:i2).flux ») returns flux(i1:i2). This is an AoS with data(t) and time(t) below, which can be of different sizes for the various indices i1:i2

• get (« magnetics.flux_loop(i1:i2).flux.data ») returns data(i1:i2,t) in homogeneous case, and an error message otherwise.

• ids_get(<path_including_indices>)
  
  • output parameters
    • array of primitive types (if query points to field of primitive type)
    • array of structures (if query points to field of AoS type or structure)
• query syntax 
  
  • separators ( / ) - path within tree
  • brackets ()    - array
  • indices (fortran style)
    • ":" all elements
    • "x:y" (from x to y)
    • ":y" from begin to y
    • "x:" from x to the last 
  • only the last AoS can contain indices:
    • YES: "path/to/field/with/ancestorAoS(1)/field/AoS(n:m)"
    • NO: "path/to/field/with/ancestorAoS(x:y)/field/AoS(1)"

path/to/field/with/ancestorAoS(1)/field/AoS(n:m) -> AoS(n:m) 

ancestorAoS(x:y)/field(:) --> field(:,x:y)

5. Time issues

5.1. AoS

5.2.  time independent data (no AoS3 on path)

5.3. members of timed AoS (AoS3)

•  single index from the ancestor AoS is requested, so no reshaping should be done, and no attempt to fill in time arrays should be done. 
• ERROR (because of  lack of time info available in returned data)

5.4.  time dependent vectors/arrays

6. Shape of returned arrays

/path/with/AoS(i1:i2)/data

lets assume:

+ i1=1; i2=3 => number of AoS to be found ("range") is 2

+ len (data) == 5,

+ data for AoS(i1) = {11, 12, 13, 14, 15}

+ data for AoS(i2) = {21, 22, 23, 24, 25}

6.1. Non timed AoS

get (« magnetics.flux_loop(i1:i2).flux ») à flux(i1:i2, t)

If AoS is NON TIMED (AoS1 or AoS2) return array has shape (range, data_len)

In NumPy notation:

[[11, 12, 13, 14, 15]

[21, 22, 23, 24, 25]]

e.g.

arr(0,1) = 12

arr(1,2) = 23

6.2. Timed AoS

get (« equilibrium.time_slice(t1:t2).profiles_1d.q ») à q(:, t1:t2)

If AoS is TIMED (AoS3) return array has shape (data_len, range)

In NumPy notation:

[ [11,21]

 [12,22]

 [13,23]

 [14,24]

 [15,25] ]

e.g.

arr(0,1) = 21

arr(2,1) = 23

OPEN POINTS:

• AoS as ancestor(s) of queried data
  • once implemented mechanism for creation of AoS could be reused to "go through" ancestors
• returned value 
  • type provided by user?
  • AoS? if not - functionality can be placed at the Low Level and available for all HLIs (however it could be a problem with returned type  anyway)
• Level of nesting
  • path/AoS(indices)/x/y/z ?