# 暑假轨迹

### 谢益辉 / 2009-08-28

library(maps)
x = structure(list(city = c("Beijing", "Yichang",
"Qingdao", "Tokyo", "Seattle", "Minneapolis", "DC", "Ames"),
latitude = c(39.908173, 30.691967, 36.066348, 35.689488,
47.620973, 44.977482, 38.892091, 42.022864),
longitude = c(116.397947,
111.286471, 120.382771, 139.691706, -122.347276, -93.264351,
-77.024055, -93.626792)), .Names = c("city", "latitude",
"longitude"), row.names = c(NA, -8L), class = "data.frame")
library(animation)
##saveMovie({
idx = c( 1, 2, 1, 3, 1, 4, 5, 6, 7, 8 )
for (i in 1:length(idx)) {
map(xlim = c(-128, 158), ylim = c(17, 54))
text(-48, 32, x$city[idx[i]], font = 2) points(x$longitude, x$latitude, pch = 20, col = "red") if (i > 1) arrows(x$longitude[idx[i - 1]], x$latitude[idx[i - 1]], x$longitude[idx[i]], x$latitude[idx[i]], length = 0.1, col = "gray") points(x$longitude[idx[i]], x\$latitude[idx[i]], pch = 19,
col = "blue")
Sys.sleep(1)
}
##}, moviename = "travel-in-summer", outdir = getwd(),
## para = list(mar = rep(0, 4)), width = 600, height = 100)


Iowa就是一片大农场，这地方，有人觉得是地狱，有人觉得是天堂。因为除了学习就是运动，没什么太多吃喝玩乐的地方。昨天俺们Dan Nordman老师说，晚上你要是觉得无聊了，不妨把讲义上的定理3拿出来证明一下，那定理还是有一定难度的（意即：可以打发足够多的时间）。