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Set Fields Information

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yt_get_FieldsPtr 

int yt_get_FieldsPtr( yt_field **field_list )
  • Usage: Get the yt_field array pointer where libyt access fields information from. Each MPI rank should call this function and fill them in. If you don’t have any fields, then skip this.
  • Return: YT_SUCCESS or YT_FAIL

:warning: Every MPI rank must call this API and fill in the field information in the same order. libyt does not broadcast and sync information here.

yt_field

  • const char* field_name (Default=NULL)
    • Usage: Field name. Refer to Naming and Field Information for how field names and yt fields are linked and reused.

      :pencil2: Please make sure the lifetime of field_name covers the whole in situ analysis process. libyt only borrows this name and does not make a copy.

  • const char* field_type (Default="cell-centered")
    • Usage: Define type of the field.
    • Valid Value:
      • "cell-centered": Cell-centered data.
      • "face-centered": Face-centered data. For more details, see Face-Centered Field.
      • "derived_func": Derived field data. When you want your simulation code to generate or convert existing data for yt, set to this. See Derived Field on how to set them.

        :pencil2: Please make sure the lifetime of field_type covers the whole in situ analysis process. libyt does not make a copy.

  • short field_ghost_cell[6] (Default=0)
    • Usage: Number of ghost cell to be ignored at the beginning and the end of each dimension. This is in the point of view of the data array.
      field_ghost_cell[0]: Number of ghost cell to be ignored at the beginning of 0-dim of the data.
      field_ghost_cell[1]: Number of ghost cell to be ignored at the end of 0-dim of the data.
      field_ghost_cell[2]: Number of ghost cell to be ignored at the beginning of 1-dim of the data.
      field_ghost_cell[3]: Number of ghost cell to be ignored at the end of 1-dim of the data.
      field_ghost_cell[4]: Number of ghost cell to be ignored at the beginning of 2-dim of the data.
      field_ghost_cell[5]: Number of ghost cell to be ignored at the end of 2-dim of the data.
    • Valid Value: Must be greater than or equal to 0.
  • yt_dtype field_dtype (Default=YT_DTYPE_UNKNOWN)
    • Usage: Data type of the field.
    • Valid Value: yt_dtype
  • bool contiguous_in_x (Default=true)
    • Usage: Is the 3D data array define as [z][y][x], which is x address alters first.
    • Valid Value:
      • true: Data is in x-address alters first orientation, which is [z][y][x].
      • false: Data is in z-address alters first orientation, which is [x][y][z].
  • void (*derived_func) (const int, const long *, const char *, yt_array*) (Default=NULL)
    • Usage: Function pointer to generate derived field data when input grid id. This is only used in derived field, which is when field_type set to derived_func (field_type="derived_func"). See Derived Field for more information.
  • const char* field_unit (Default="")
    • Usage: Unit of the field, using yt unit system.

      :pencil2: Please make sure the lifetime of field_unit covers yt_commit.

  • int num_field_name_alias (Default=0)
    • Usage: Number of name aliases in field_name_alias.
  • const char** field_name_alias (Default=NULL)
    • Usage: Name aliases.

      :pencil2: Please make sure the lifetime of field_name_alias covers yt_commit.

  • const char* field_display_name (Default=NULL)
    • Usage: Display name of the field on the output figure. If not set, yt uses its field name instead.

      :pencil2: Please make sure the lifetime of field_display_name covers yt_commit.

:information_source: libyt borrows the full field information class (class XXXFieldInfo) from frontend. It is OK not to set a field’s field_unit, num_field_name_alias, field_name_alias, field_display_name, if this field_name is already inside your frontend. If you are adding a totally new field, please add them. libyt will add these new field information alongside with your original one.

Example 

/* libyt API */  
yt_field *field_list;
yt_get_FieldsPtr( &field_list );

// cell-centered type field "Dens" 
field_list[0].field_name = "Dens";  
field_list[0].field_type = "cell-centered";  
field_list[0].field_dtype = ( typeid(real) == typeid(float) ) ? YT_FLOAT : YT_DOUBLE;  
const char *field_name_alias[] = {"Name Alias 1", "Name Alias 2", "Name Alias 3"};  
field_list[0].field_name_alias = field_name_alias;  
field_list[0].num_field_name_alias = 3;  
for(int d = 0; d < 6; d++){
    field_list[0].field_ghost_cell[d] = GHOST_CELL;  
}