add vignetter for rpluce

vignettes/v6-simulate-data.Rmd

@@ -0,0 +1,25 @@
+---
+title: "6. Simulating Ranking Data"
+output: rmarkdown::html_vignette
+vignette: >
+  %\VignetteIndexEntry{6. Simulating Ranking Data}
+  %\VignetteEngine{knitr::rmarkdown}
+  %\VignetteEncoding{UTF-8}
+---
+
+```{r, include = FALSE}
+knitr::opts_chunk$set(
+  collapse = TRUE,
+  comment = "#>"
+)
+```
+
+In this vignette, we describe our helper function `rpluce` to simulate ranking data based on the Plackett-Luce model, also known as the rank-order logit or random utility model. To draw from the PL, `rpluce` requires a vector of probabilities that `t` items will be selected as the first choice, respectively. For each unit, the output provides a full ordering of `t` items with distinct alphabet letters.
+
+```{r}
+draw <- rpluce(n = 50,
+               t = 4,
+               prob = c(0.4, 0.2, 0.2, 0.2))
+
+head(draw)
+```