OPH_SUBSET¶

Description¶

Type

Data Process.

Behaviour

It performs a subsetting operation along dimensions of a datacube. Dimension values are used as input filters.

Parameters

• cube: name of the input datacube. The name must be in PID format.

• schedule: scheduling algorithm. The only possible value is 0, for a static linear block distribution of resources.

• subset_dims: dimension names of the datacube used for the subsetting. Multiple-value field: list of dimensions separated by “|” can be provided and must be the same number of “subset_filter”.

• subset_filter: enumeration of comma-separated elementary filters (1 series of filters for each dimension). Multiple-value field: list of filters separated by “|” can be provided; it must be the same number of “subset_dims”. In case “subset_type” is “index” a filter can be expressed as

  • index : select a single value, specified by its index;
  • start_index:stop_index : select elements from start_index to stop_index;
  • start_index:stride:stop_index : select elements from start_index to stop_index with a step of stride.

  Indexes are integers from 1 to the dimension size. It can be also used "end" to specify the index of the last element. Example: subset_dims=lat|lon;subset_filter=1:10|20:end.

  In case “subset_type” is “coord” a filter can be expressed as

  • value: select a specific value;
  • start_value:stop_value: select elements from start_value to stop_value; return an error if this set is empty.

  Values should be numbers. Example: subset_dims=lat|lon;subset_filter=35:45|15:20; for time dimensions the option “time_filter” can be enabled, so that the following date formats can be also used:

  • yyyy
  • yyyy-mm
  • yyyy-mm-dd
  • yyyy-mm-dd hh
  • yyyy-mm-dd hh:mm
  • yyyy-mm-dd hh:mm:ss

  Time interval bounds must be separated with “_”. Refer to a season using the corresponding code: DJF for winter, MAM for spring, JJA for summer or SON for autumn.

  Multiple-value field: list of filters separated by “|” can be provided and must be the same number of “subset_dims”.

• subset_type : if set to “index” (default), the “subset_filter” is considered on dimension index; with “coord”, filter is considered on dimension values.

• time_filter: enable filters using dates for time dimensions; enabled by default.

• offset: it is added to the bounds of subset intervals defined with “subset_filter” in case of “coord” filter type is used.

• grid: optional argument used to identify the grid of dimensions to be used (if the grid already exists) or the one to be created (if the grid has a new name). If it isn’t specified, no grid will be used.

• container: name of the container to be used to store the output cube; by default, it is the input container.

• check_grid: optional flag to be enabled in case the values of grid have to be checked (valid only if the grid already exists).

• description: additional description to be associated with the output cube.

System parameters

• exec_mode: operator execution mode. Possible values are async (default) for asynchronous mode, sync for synchronous mode with json-compliant output.
• ncores: number of parallel processes to be used (min. 1).
• nthreads: number of parallel threads per process to be used (min. 1).
• sessionid: session identifier used server-side to manage sessions and jobs. Usually, users don’t need to use/modify it, except when it is necessary to create a new session or switch to another one.
• objkey_filter: filter on the output of the operator written to file (default=all => no filter, none => no output, subset => shows operator’s output PID as text).

Examples

Extract the subset of values in the range 1-10 of dimension “lat” and 20-30 of dimension “lon”:

[OPH_TERM] >>  oph_subset cube=URL/1/1;subset_dims=lat|lon;subset_filter=1:10|20:30;grid=new_grid;

Arguments¶