thisisnic commented on a change in pull request #10624:
URL: https://github.com/apache/arrow/pull/10624#discussion_r670256189
##########
File path: r/R/dplyr-functions.R
##########
@@ -280,6 +284,81 @@ nse_funcs$str_trim <- function(string, side = c("both",
"left", "right")) {
Expression$create(trim_fun, string)
}
+nse_funcs$substr <- function(string, start, stop) {
+ assert_that(
+ length(start) == 1,
+ msg = "`start` must be length 1 - other lengths are not supported in Arrow"
+ )
+ assert_that(
+ length(stop) == 1,
+ msg = "`stop` must be length 1 - other lengths are not supported in Arrow"
+ )
+
+ if (start <= 0) {
+ start <- 1
+ }
+
+ if (stop < start) {
+ stop <- 0
+ }
+
+ Expression$create(
+ "utf8_slice_codeunits",
+ string,
+ options = list(start = start - 1L, stop = stop)
+ )
+}
+
+nse_funcs$substring <- function(text, first, last = 1000000L) {
+ assert_that(
+ length(first) == 1,
+ msg = "`first` must be length 1 - other lengths are not supported in Arrow"
+ )
+ assert_that(
+ length(last) == 1,
+ msg = "`last` must be length 1 - other lengths are not supported in Arrow"
+ )
+
+ if (first <= 0) {
+ first <- 1
+ }
+
+ if (last < first) {
+ last <- 0
+ }
+
+ Expression$create(
+ "utf8_slice_codeunits",
+ text,
+ options = list(start = first - 1L, stop = last)
+ )
+}
+
+nse_funcs$str_sub <- function(string, start = 1L, end = -1L) {
+ assert_that(
+ length(start) == 1,
+ msg = "`start` must be length 1 - other lengths are not supported in Arrow"
+ )
+ assert_that(
+ length(end) == 1,
+ msg = "`end` must be length 1 - other lengths are not supported in Arrow"
+ )
+
+ if (start == 0) start <- 1
+
+ if (end == -1) end <- .Machine$integer.max
+
+ if (end < start) end <- 0
+
+ if (start > 0) start <- start - 1L
Review comment:
Hmm, this also makes setting `start` to 1 if it's 0 totally redundant so
I'll remove that too
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