# Extract a subset of a larger DVH list This function is designed to isolate one or more structure(s) from a list of DVH lists according to user input. methods ```r ## S3 method for class 'DVH.list' subset(x, structure, patient, ID, constraint, ignore.case=TRUE, select) ``` ## Arguments - `x`: Represents a `DVH.list` object (e.g. generated by `read.DVH()`). - `structure`: Vector used to sub-select structures from `x`; may be a character vector containing structure names (regular expressions may be specified if desired, see `regex` for more details). - `patient`: Vector used to sub-select specific patient data from `x`; may be a character vector containing patient names (regular expressions may be specified if desired, see `regex` for more details). - `ID`: Vector used to sub-select specific patient data from `x` using exact matching on patient identifiers. - `constraint`: Vector of one or more dosimetric constraints to apply to `x` to assess whether or not each component DVH should be included in the resultant list. More than one parameter may be specified at a time. Parameter specification should be of the form `" ()"`: `` is equivalent to `"V"` or `"D"`, representing a volume or dose, respectively; `` usually denotes a numerical value specifying the dose or volume; `` represents the dose or volume units (`"cGy"`, `"Gy"`, `"%"`, or `"cc"`); `` represents a logical comparator (e.g. `">="` or `"<"` or `"!="`); `` represents a comparative value; and `` represents the units of comparison (e.g. `"%"` or `"Gy"`). An example would be `"V20Gy < 50(%)"` which represents a test of whether or not the volume of the structure receiving at least 20Gy dose is less than 50% of the overall structure volume. Dose ranges may also be specified, for instance `"V10-20Gy"` or `"V<20Gy"`. Specialized dosimetric keywords may also be used: `"Dmax"` (maximum dose), `"Dmin"` (minimum dose), `"Dmean"` (mean dose), `"Dmedian"` (median dose), `"Dintegral"` (estimated integral dose), `"DRx"` (prescription dose), and `"volume"` (total structure volume). If an improper parameter is specified however, `NA` results will be returned. See package documentation (vignette) for more details. - `ignore.case`: Logical value specifying whether or not to use case-sensitive pattern matching; if `TRUE` (default), case is ignored during matching, and if `FALSE`, the pattern matching is **case sensitive**. - `select`: Must be one of `"all"` (default), `"any"`, or `"none"`. This value specifies the how to combine multiple selection inputs. When `select = "all"`, a given DVH is only included in the resulting DVH list when it matches with all specififed inputs (for instance, must be a specific structure from a specific patient). When `select = "any"`, a DVH may be included in the result DVH list if it matches any specified inputs. When `select = "none"`, a DVH will only be included int eh resulting DVH list if it does not match with any of the specified criteria. For more details, see examples, below. ## Returns Returns a single DVH list ## Author(s) Reid F. Thompson (reid.thompson@gmail.com ) ## See Also `DVH.list` ## Examples ```r data(list="RadOnc", package="RadOnc") subset(johndoe, structure="kidney", constraint="Dmean < 500(cGy)", ignore.case=TRUE) subset(johndoe, constraint="volume > 200(cc)") ```

subset function