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Allow users to add and subtract from default attributes in addition to providing a given set of attributes.


select_spct_attributes(attributes, attributes.default = spct_attributes())

spct_attributes(.class = "all", attributes = "*")


attributes, attributes.default

character vector or a list of character vectors.


character Name of spectral class.


A character vector of attribute names.


Vectors of character strings passed as argument to attributes are parsed so that if the first member string is "+", the remaining members are added to those in attributes.default; if it is "-" the remaining members are removed from in attributes.default; and if it is "=" the remaining members replace those in in attributes.default. If the first member is none of these three strings, the behaviour is the same as when the first string is "=". If attributes is NULL all the attributes in attributes.default are used and if it is "" no attribute names are returned, "" has precedence over other member values. The order of the names of annotations has no meaning: the vector is interpreted as a set except for the three possible "operators" at position 1.