---
title: sample.system()
subtitle: Demonstration of the systematic sampling
date: '2017-04-04'
slug: sample-system
---

The whole sample frame is denoted by a matrix (`nrow * ncol`) in the
plane, and the sample points with equal intervals are drawn out according to
a random starting point. The points being sampled are marked by red circles.
 
```{r demo-a, cache=TRUE, interval=1}
library(animation)
ani.options(nmax = 50)
par(mar = rep(1, 4), lwd = 2)
sample.system()
```
