Interfaces/R/Rserver/Formats
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The result of an Rserver get command may be a SEXP expression - a recursively encoded list of names and values. Such expressions can be converted to a map (a two column table of names and values), which is a more convenient form for J. The core methods are:
- Rgetexp returns the original SEXP
- Rget returns a map
In each case, tag labels in attributes have names preceded with a ` (backtick):
Rgetexp
Rgetexp returns the result in the original SEXP format. This is useful for debugging, but inconvenient for practical use.
Rgetexp 'x=factor(c("one","two","three","four"))'
┌────────────────────────────────────────────┬───────┐
│┌────────────────────┬───────┬──────┬──────┐│2 4 3 1│
││┌────┬───┬─────┬───┐│`levels│factor│`class││ │
│││four│one│three│two││ │ │ ││ │
││└────┴───┴─────┴───┘│ │ │ ││ │
│└────────────────────┴───────┴──────┴──────┘│ │
└────────────────────────────────────────────┴───────┘
Rget
Rget returns the result as a map, i.e. a 2-column matrix of names and values:
Rget 'x' ┌───────┬────────────────────┐ │`class │factor │ ├───────┼────────────────────┤ │`data │2 4 3 1 │ ├───────┼────────────────────┤ │`levels│┌────┬───┬─────┬───┐│ │ ││four│one│three│two││ │ │└────┴───┴─────┴───┘│ └───────┴────────────────────┘
The tag `data' is used where the name is not given.
Where the SEXP is nested, the name paths are separated by $:
Rcmd 'data(OrchardSprays)' Rget 'OrchardSprays' ┌─────────────────┬─────────────────────────────────────────────────────────────... │`class │data.frame ... ├─────────────────┼─────────────────────────────────────────────────────────────... │`row.names │1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2... ├─────────────────┼─────────────────────────────────────────────────────────────... │colpos │1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4 4 4... ├─────────────────┼─────────────────────────────────────────────────────────────... │decrease │57 95 8 69 92 90 15 2 84 6 127 36 51 2 69 71 87 72 5 39 22 16... ├─────────────────┼─────────────────────────────────────────────────────────────... │rowpos │1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7... ├─────────────────┼─────────────────────────────────────────────────────────────... │treatment$`class │factor ... ├─────────────────┼─────────────────────────────────────────────────────────────... │treatment$`data │4 5 2 8 7 6 3 1 3 2 8 4 5 1 6 7 6 8 1 5 4 3 7 2 8 1 5 3 6 7 2... ├─────────────────┼─────────────────────────────────────────────────────────────... │treatment$`levels│┌─┬─┬─┬─┬─┬─┬─┬─┐ ... │ ││A│B│C│D│E│F│G│H│ ... │ │└─┴─┴─┴─┴─┴─┴─┴─┘ ... └─────────────────┴─────────────────────────────────────────────────────────────...
Rget can also take an optional left argument that specifies the portion of the map that should be returned.
'decrease' Rget 'OrchardSprays' 57 95 8 69 92 90 15 2 84 6 127 36 51 2 69 71 87 72 5 39 22 16 72 4 130 4 114 9 ... 'treatment' Rget 'OrchardSprays' ┌───────┬───────────────────────────────────────────────────────────────────────... │`class │factor ... ├───────┼───────────────────────────────────────────────────────────────────────... │`data │4 5 2 8 7 6 3 1 3 2 8 4 5 1 6 7 6 8 1 5 4 3 7 2 8 1 5 3 6 7 2 4 5 4 7 1... ├───────┼───────────────────────────────────────────────────────────────────────... │`levels│┌─┬─┬─┬─┬─┬─┬─┬─┐ ... │ ││A│B│C│D│E│F│G│H│ ... │ │└─┴─┴─┴─┴─┴─┴─┴─┘ ... └───────┴───────────────────────────────────────────────────────────────────────...
Extracting Results
The Rmap_rserver_ utility can retrieve results from the map structure, for example:
'x' Rset 12 18 24 30 36 42 48 'y' Rset 5.27 5.68 6.25 7.21 8.02 8.71 8.42 lxy=. Rget 'lm(y ~ x)' Rmap_rserver_ lxy NB. monadic Rmap returns keys from map structure ┌──────┬──────┬────┬────────────────────────┬──────────────┬───────────┬────────┬... │`class│assign│call│coefficients$(Intercept)│coefficients$x│df.residual│effects$│... └──────┴──────┴────┴────────────────────────┴──────────────┴───────────┴────────┴... 'coefficients$x' Rmap_rserver_ lxy 0.10285714286 'coefficients' Rmap_rserver_ lxy ┌───────────┬─────────────┐ │(Intercept)│3.9942857143 │ ├───────────┼─────────────┤ │x │0.10285714286│ └───────────┴─────────────┘ 'qr$qr$`data' Rmap_rserver_ lxy _2.64575 _79.3725 0.377964 31.749 0.377964 0.0334734 0.377964 _0.155509 0.377964 _0.344491 0.377964 _0.533473 0.377964 _0.722456