Boolean conditions {GCDkit}R Documentation

Select subset by Boolean condition

Description

Selecting subsets of the current dataset using Boolean conditions that can query both numeric fields and labels. Regular expressions can be employed to search the labels.

Details

The menu item 'Select subset by Boolean', connected to the function selectSubset, enables the user to query by any combination of the numeric columns and labels in the whole dataset. The current data will be replaced by its newly chosen subset.

First, the user is prompted to enter a search pattern which can contain conditions that may employ most of the comparison operators common in R, i.e. < (lower than), > (greater than), <= (lower or equal to), >= (greater or equal to), = or == (equal to), != (not equal to). The character strings should be quoted. The conditions can be combined together by logical and, or and brackets.

Logical and can be expressed as .and. .AND. &

Logical or can be expressed as .or. .OR. |

Please note that at the moment no extra spaces can be handled (apart from in quoted character strings).

Value

Overwrites the data frame 'labels' and numeric matrix 'WR' by subset that fulfills the search criteria.

Author(s)

Vojtech Janousek, vojtech.janousek@geology.cz

See Also

regular.expressions regex

Examples

## Not run: 
# Valid search patterns

Intrusion="Rum"
# Finds all analyses from Rum

Intrusion="Rum".and.SiO2>65
Intrusion="Rum".AND.SiO2>65
Intrusion="Rum"&SiO2>65
# All analyses from Rum with silica greater than 65 
# (all three expressions are equivalent) 


MgO>10&(Locality="Skye"|Locality="Islay")
# All analyses from Skye or Islay with MgO greater than 10

MgO>=10&(Locality!="Skye"&Locality!="Islay")
# All analyses from any locality except Skye and Islay with MgO greater 
# or equal to 10

Locality="^S"
# All analyses from any locality whose name starts with capital S

## End(Not run)

[Package GCDkit version 3.00 Index]