mfe_lookup: match first entry in lookup table

In HanOostdijk/HOQCutil: Utilities by Han Oostdijk

match first entry in lookup table

Description

Returns for the entries in a vector the first entry in the lookup table lookup_df that matches the entry or in case of no-match a default. See Details

Usage

mfe_lookup(
  datavec,
  lookup_df,
  lookup_search_col = 1,
  lookup_result_col = 2,
  default = TRUE,
  case_sensitive = FALSE
)

Arguments

datavec	Character vector with elements that are to be matched in lookup table
lookup_df	Data.frame containing a search and a result column
lookup_search_col	Integer indicating the number of the search column (in lookup_df)
lookup_result_col	Integer indicating the number of the result column (in lookup_df)
default	Boolean or character string indicating the value to use when no match is found (See Details)
case_sensitive	Boolean indicating if the match is case sensitive

Value

Character vector with the same length as datavec with the result of the match

Details

Each element in datavec is compared with the elements in the lookup_search_col column of the lookup_df data.frame. This is done with a expression of the form grepl(.,.,fixed=T) where the first dot represents an element of the lookup_search_col column and the second dot the datavec element (both after capitalizing the character strings when case_sensitive==F). The element of the lookup_search_col column can contain more than one element and in that case for each element a match must be found. In the example below a match is found for the fourth element if the data element matches both x3 and x4. If a match is found the corresponding element in the lookup_result_col column is returned and when more matches are found only the first is returned. So for the first element in datavec we return 'one' and not 'two': 'x1' matches first even when you could say that 'x1;x2' matches more. Therefore the more specified case should be specified first: see e.g. the 'x3;x4' case in the example.
For an entry without a match will be returned:

• the entry itself when default == TRUE (the default)

• the empty string when default == FALSE

• the contents of default when default is not a boolean

Examples

## Not run: 
lookup_df = tibble::tribble(
  ~col1, ~col2,
  'x1' , 'one' ,
  'x1;x2' , 'two' ,
  'X2' , 'two' ,
  'x3;x4' , 'three four' ,
  'x3' , 'three'
)  %>%
  transform(col1 = strsplit(col1, ";"))

datavec = c('x1 and x2', 'only x2', 'x5', 'x3 and x4','x3 and x5')

mfe_lookup(datavec,lookup_df,default=TRUE)
# c("one", "two", "x5", "three four", "three" )

mfe_lookup(datavec,lookup_df,default=FALSE)
# c("one", "two", "", "three four", "three" )

mfe_lookup(datavec,lookup_df,default='not found!')
# c("one", "two", "not found!", "three four", "three" )

mfe_lookup(datavec,lookup_df,case_sensitive=TRUE)
# c("one", "only x2", "x5", "three four", "three" )


## End(Not run)

HanOostdijk/HOQCutil documentation built on July 28, 2023, 5:56 p.m.