diff --git a/NAMESPACE b/NAMESPACE
index e800283ea546e4cc98deebd22368186296d4bda8..8f2dbd6ba28582332e6945de9bcd7dd9aa26bb37 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -5,6 +5,8 @@ export(calc_vif)
 export(explore_na)
 export(impute)
 export(panel_cor)
+export(panel_hist)
+export(panel_lines)
 export(plot_statespace_ch)
 export(plot_statespace_ed)
 export(statespace_ch)
diff --git a/R/panel_cor.R b/R/panel_cor.R
deleted file mode 100644
index 90b6f527044fa1e91643f2c765c3facdab3d4458..0000000000000000000000000000000000000000
--- a/R/panel_cor.R
+++ /dev/null
@@ -1,40 +0,0 @@
-#' Show correlation coefficient in pairs plot
-#'
-#' This and the other functions are utility functions for the pairs plot.
-#' \code{panel_cor} shows the Pearson product-moment correlation coefficient in
-#' the selected panels. \code{panel_lines} shows the regression line and
-#' \code{panel_hist} histograms.
-#'
-#' @param x numeric vector
-#' @param y numeric vector
-
-#' @seealso \code{\link{pairs}}
-#' @export
-
-panel_cor <- function(x, y) {
-  par(usr = c(0, 1, 0, 1))
-  r <- stats::cor(x, y, use = "pairwise.complete.obs")
-  txt <- format(r, digits = 1)
-  text(0.5, 0.5, txt, cex = 0.9/strwidth(txt) * abs(r))
-}
-
-#' @rdname panel_cor
-panel_lines <- function (x, y) {
-  points(x, y, bg = NA, cex = 1)
-  sel <- is.finite(x) & is.finite(y)
-  if (any(sel)){
-    lml <- stats::lm(y[sel] ~ x[sel])
-    abline(lml, col = "blue")}
-}
-
-
-#' @rdname panel_cor
-panel_hist <- function(x) {
-  usr <- par("usr")
-  par(usr = c(usr[1:2], 0, 1.5) )
-  h <- hist(x, plot = FALSE)
-  breaks <- h$breaks
-  nB <- length(breaks)
-  y <- h$counts / max(h$counts)
-  rect(breaks[-nB], 0, breaks[-1], y, col = "grey80")
-}
diff --git a/R/panel_funcs.R b/R/panel_funcs.R
new file mode 100644
index 0000000000000000000000000000000000000000..7602c3067e8bdc521dfd00895a69e6377e71abba
--- /dev/null
+++ b/R/panel_funcs.R
@@ -0,0 +1,48 @@
+#' Show correlation coefficient, histogram or regression lines in pairs plot
+#'
+#' \code{panel_cor}, \code{panel_lines}  and \code{panel_hist} are utility functions
+#' for the pairs plot. \code{panel_cor} shows the Pearson product-moment correlation
+#' coefficient in the selected panels. \code{panel_lines} shows the regression line and
+#' \code{panel_hist} histograms.
+#'
+#' @param x numeric vector
+#' @param y numeric vector
+#' @name panel_funcs
+
+#' @seealso \code{\link{pairs}}
+#' @examples
+#' z <- matrix(rnorm(40), ncol = 4)
+#' pairs(z, upper.panel = panel_cor,
+#' lower.panel = panel_lines, diag.panel = panel_hist)
+NULL
+
+#' @rdname panel_funcs
+#' @export
+panel_cor <- function(x, y) {
+  par(usr = c(0, 1, 0, 1))
+  r <- stats::cor(x, y,use = "pairwise.complete.obs")
+  txt <- format(r, digits = 1)
+  text(0.5, 0.5, txt, cex = 0.9/strwidth(txt) * abs(r))
+}
+
+#' @rdname panel_funcs
+#' @export
+panel_lines <- function (x, y) {
+  points(x, y, bg = NA, cex = 1)
+  sel <- is.finite(x) & is.finite(y)
+  if (any(sel)){
+    lml <- stats::lm(y[sel] ~ x[sel])
+    abline(lml, col = "blue")}
+}
+
+#' @rdname panel_funcs
+#' @export
+panel_hist <- function(x) {
+  usr <- par("usr")
+  par(usr = c(usr[1:2], 0, 1.5) )
+  h <- hist(x, plot = FALSE)
+  breaks <- h$breaks
+  nB <- length(breaks)
+  y <- h$counts / max(h$counts)
+  rect(breaks[-nB], 0, breaks[-1], y, col="grey80")
+}
diff --git a/man/panel_cor.Rd b/man/panel_cor.Rd
deleted file mode 100644
index ed53cf36c7a21d68f52cd60695954177e43d1d00..0000000000000000000000000000000000000000
--- a/man/panel_cor.Rd
+++ /dev/null
@@ -1,28 +0,0 @@
-% Generated by roxygen2: do not edit by hand
-% Please edit documentation in R/panel_cor.R
-\name{panel_cor}
-\alias{panel_cor}
-\alias{panel_lines}
-\alias{panel_hist}
-\title{Show correlation coefficient in pairs plot}
-\usage{
-panel_cor(x, y)
-
-panel_lines(x, y)
-
-panel_hist(x)
-}
-\arguments{
-\item{x}{numeric vector}
-
-\item{y}{numeric vector}
-}
-\description{
-This and the other functions are utility functions for the pairs plot.
-\code{panel_cor} shows the Pearson product-moment correlation coefficient in
-the selected panels. \code{panel_lines} shows the regression line and
-\code{panel_hist} histograms.
-}
-\seealso{
-\code{\link{pairs}}
-}
diff --git a/man/panel_funcs.Rd b/man/panel_funcs.Rd
new file mode 100644
index 0000000000000000000000000000000000000000..2b33b8d7bd4e815a9019b241ac6fec5c4700684b
--- /dev/null
+++ b/man/panel_funcs.Rd
@@ -0,0 +1,34 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/panel_funcs.R
+\name{panel_funcs}
+\alias{panel_funcs}
+\alias{panel_cor}
+\alias{panel_lines}
+\alias{panel_hist}
+\title{Show correlation coefficient, histogram or regression lines in pairs plot}
+\usage{
+panel_cor(x, y)
+
+panel_lines(x, y)
+
+panel_hist(x)
+}
+\arguments{
+\item{x}{numeric vector}
+
+\item{y}{numeric vector}
+}
+\description{
+\code{panel_cor}, \code{panel_lines}  and \code{panel_hist} are utility functions
+for the pairs plot. \code{panel_cor} shows the Pearson product-moment correlation
+coefficient in the selected panels. \code{panel_lines} shows the regression line and
+\code{panel_hist} histograms.
+}
+\examples{
+z <- matrix(rnorm(40), ncol = 4)
+pairs(z, upper.panel = panel_cor,
+lower.panel = panel_lines, diag.panel = panel_hist)
+}
+\seealso{
+\code{\link{pairs}}
+}