Extract Numeric Values from Strings

Extracts numeric values from character strings using regular expressions. The function supports integers, decimal numbers, and scientific notation.

Usage

strVal(
  x,
  collapse = FALSE,
  output = c("character", "numeric"),
  dec = getOption("OutDec")
)

Arguments

x

a character vector

collapse

logical; if TRUE, all extracted numbers per element of x are concatenated into a single string. Otherwise, a list of character vectors is returned.

output

character; controls the type of the returned values. "character" (default) returns strings; "numeric" coerces extracted values to numeric.

dec

character; decimal separator used in the input. Defaults to getOption("OutDec").

Value

If collapse = FALSE, a list of character or numeric vectors containing the extracted values for each element of x. If collapse = TRUE, a character or numeric vector with concatenated values per element.

Details

The function detects numeric values including optional signs, decimal parts, and scientific notation (e.g., "1.23e-4").

Whitespace between sign and number (e.g., "- 2.5") is tolerated and removed before returning results.

If output = "numeric" and the decimal separator dec differs from the current system setting (getOption("OutDec")), values are converted accordingly before coercion.

See also

as.numeric(), stringi::stri_extract_all_regex()

string-overview for an overview of all string utilities in pharos.

Examples

x <- c("value = 12.5", "x = -3.2e2 and 7", "no numbers here")

# extract as character
strVal(x)
#> [[1]]
#> [1] "12.5"
#> 
#> [[2]]
#> [1] "-3.2e2" "7"     
#> 
#> [[3]]
#> [1] NA
#> 

# extract as numeric
strVal(x, output = "numeric")
#> [[1]]
#> [1] 12.5
#> 
#> [[2]]
#> [1] -320    7
#> 
#> [[3]]
#> [1] NA
#> 

# concatenate values
strVal(x, collapse = TRUE)
#> [1] "12.5"    "-3.2e27" "NA"     

# different decimal separator
strVal("value = 3,14", dec = ",", output = "numeric")
#> [[1]]
#> [1] 3.14
#>