query
Query an Object for Information
The function query
can be used to search an object
for a keyword.
The data.set
and importer
methods perform such a search
through the annotations and value labels of
the items in the data set.
- Keywords
- manip
Usage
query(x,pattern,…)
# S4 method for data.set
query(x,pattern,…)
# S4 method for importer
query(x,pattern,…)# S4 method for item
query(x,pattern,…)
# (Called by the methods above.)
Arguments
- x
an object
- pattern
a character string that gives the pattern to be searched for
- …
optional arguments such as
fuzzy
logical, TRUE by default; use fuzzy search via
agrep
or regexp search viagrep
extended
logical, defaults to FALSE; passed to
grep
perl
logical, defaults to TRUE; passed to
grep
fixed
logical, defaults to TRUE; passed to
grep
ignore.case
insertions
numerical value, defaults to 0.999999999; passed to
agrep
deletions
numerical value, defaults to 0; passed to
agrep
substitutions
numerical value, defaults to 0; passed to
agrep
Value
If both the annotation and the value labels of an item match the pattern
the query
method for 'item' objects returns a list containing the annotation
and the value labels, otherwise if only the annotation or the value labels
match the pattern, either the annotation or the value labels are returned,
otherwise if neither matches the pattern, query
returns NULL
.
The methods of query
for 'data.set' and 'importer' objects return
a list of all non-NULL
query results of all items contained by these
objects, or NULL
.
Examples
# NOT RUN {
nes1948.por <- unzip(system.file("anes/NES1948.ZIP",package="memisc"),
"NES1948.POR",exdir=tempfile())
nes1948 <- spss.portable.file(nes1948.por)
query(nes1948,"TRUMAN")
# }