Extract the target capture group from provided patterns
Description
Extract the target capture group from provided patterns
Usage
<Expr>$str$extract(pattern, group_index)
Arguments
pattern
|
A valid regex pattern. Can be an Expr or something coercible to an Expr. Strings are parsed as column names. |
group_index
|
Index of the targeted capture group. Group 0 means the whole pattern, first group begin at index 1 (default). |
Value
String array. Contains null if original value is null or regex capture nothing.
Examples
library(polars)
df = pl$DataFrame(
a = c(
"http://vote.com/ballon_dor?candidate=messi&ref=polars",
"http://vote.com/ballon_dor?candidat=jorginho&ref=polars",
"http://vote.com/ballon_dor?candidate=ronaldo&ref=polars"
)
)
df$with_columns(
extracted = pl$col("a")$str$extract(pl$lit(r"(candidate=(\w+))"), 1)
)
#> shape: (3, 2)
#> ┌───────────────────────────────────┬───────────┐
#> │ a ┆ extracted │
#> │ --- ┆ --- │
#> │ str ┆ str │
#> ╞═══════════════════════════════════╪═══════════╡
#> │ http://vote.com/ballon_dor?candi… ┆ messi │
#> │ http://vote.com/ballon_dor?candi… ┆ null │
#> │ http://vote.com/ballon_dor?candi… ┆ ronaldo │
#> └───────────────────────────────────┴───────────┘