length and subset

NAMESPACE

@@ -1,5 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
+S3method("[",tdigest)
+S3method(length,tdigest)
 S3method(print,tdigest)
 S3method(quantile,tdigest)
 export("%>%")

R/create.R

@@ -109,6 +109,7 @@ td_create <- function(compression=100) {
 #' td <- td_create(10)
 #' td_add(td, 0, 1)
 #' td_total_count(td)
+#' length(td)
 td_total_count <- function(td) {
   stopifnot(inherits(td, "tdigest"))
   stopifnot(!is_null_xptr(td))
@@ -144,6 +145,9 @@ td_add <- function(td, val, count) {
 #'   td_add(10, 1)
 #'
 #' td_value_at(td, 0.1)
+#' td_value_at(td, 0.5)
+#' td[0.1]
+#' td[0.5]
 td_value_at <- function(td, q) {
   stopifnot(inherits(td, "tdigest"))
   stopifnot(!is_null_xptr(td))
@@ -176,3 +180,23 @@ td_merge <- function(from, into) {
   stopifnot(!is_null_xptr(into))
   .Call("Rtd_merge", from=from, into=into, PACKAGE="tdigest")
 }
+
+
+#' @rdname td_total_count
+#' @param x a tdigest object
+#' @export
+length.tdigest <- function(x) {
+  td_total_count(x)
+}
+
+#' @rdname td_value_at
+#' @param x a tdigest object
+#' @param i quantile (range 0:1)
+#' @param ... unused
+#' @export
+`[.tdigest` <- function(x, i, ...) {
+  if (length(x) == 0) return(NULL)
+  i <- as.double(i[1])
+  if ((i<=0) || (i>1)) return(NULL)
+  td_value_at(x, i)
+}

man/td_total_count.Rd

@@ -2,12 +2,17 @@
 % Please edit documentation in R/create.R
 \name{td_total_count}
 \alias{td_total_count}
+\alias{length.tdigest}
 \title{Total items contained in the t-digest}
 \usage{
 td_total_count(td)
+
+\method{length}{tdigest}(x)
 }
 \arguments{
 \item{td}{t-digest object}
+
+\item{x}{a tdigest object}
 }
 \description{
 Total items contained in the t-digest
@@ -16,4 +21,5 @@ Total items contained in the t-digest
 td <- td_create(10)
 td_add(td, 0, 1)
 td_total_count(td)
+length(td)
 }

man/td_value_at.Rd

@@ -2,14 +2,23 @@
 % Please edit documentation in R/create.R
 \name{td_value_at}
 \alias{td_value_at}
+\alias{[.tdigest}
 \title{Return the value at the specified quantile}
 \usage{
 td_value_at(td, q)
+
+\method{[}{tdigest}(x, i, ...)
 }
 \arguments{
 \item{td}{t-digest object}
 
 \item{q}{quantile (range 0:1)}
+
+\item{x}{a tdigest object}
+
+\item{i}{quantile (range 0:1)}
+
+\item{...}{unused}
 }
 \description{
 Return the value at the specified quantile
@@ -21,4 +30,7 @@ td_add(td, 0, 1) \%>\%
   td_add(10, 1)
 
 td_value_at(td, 0.1)
+td_value_at(td, 0.5)
+td[0.1]
+td[0.5]
 }