畫圖
library(lattice)
xyplot(readscr ~ mathscr,
groups = county,
data = dtar,
type=c("p", "g"),
auto.key=list(columns=4))
Select at random one school per county in the data set Caschool{Ecdat} and draw a scatter diagram of average math score mathscr against average reading score readscr for the sampled data set. Make sure your results are reproducible (e.g., the same random sample will be drawn each time).
# install.packages("Ecdat")
library(Ecdat)
#> Loading required package: Ecfun
#>
#> Attaching package: 'Ecfun'
#> The following object is masked from 'package:base':
#>
#> sign
#>
#> Attaching package: 'Ecdat'
#> The following object is masked from 'package:datasets':
#>
#> Orange
str(Caschool)
#> 'data.frame': 420 obs. of 17 variables:
#> $ distcod : int 75119 61499 61549 61457 61523 62042 68536 63834 62331 67306 ...
#> $ county : Factor w/ 45 levels "Alameda","Butte",..: 1 2 2 2 2 6 29 11 6 25 ...
#> $ district: Factor w/ 409 levels "Ackerman Elementary",..: 362 214 367 132 270 53 152 383 263 94 ...
#> $ grspan : Factor w/ 2 levels "KK-06","KK-08": 2 2 2 2 2 2 2 2 2 1 ...
#> $ enrltot : int 195 240 1550 243 1335 137 195 888 379 2247 ...
#> $ teachers: num 10.9 11.1 82.9 14 71.5 ...
#> $ calwpct : num 0.51 15.42 55.03 36.48 33.11 ...
#> $ mealpct : num 2.04 47.92 76.32 77.05 78.43 ...
#> $ computer: int 67 101 169 85 171 25 28 66 35 0 ...
#> $ testscr : num 691 661 644 648 641 ...
#> $ compstu : num 0.344 0.421 0.109 0.35 0.128 ...
#> $ expnstu : num 6385 5099 5502 7102 5236 ...
#> $ str : num 17.9 21.5 18.7 17.4 18.7 ...
#> $ avginc : num 22.69 9.82 8.98 8.98 9.08 ...
#> $ elpct : num 0 4.58 30 0 13.86 ...
#> $ readscr : num 692 660 636 652 642 ...
#> $ mathscr : num 690 662 651 644 640 ...使用分層隨機挑選。
# install.packages("sampling")
library(sampling)
set.seed(3301)
sample <- strata(dta, stratanames = c("county"), size=rep(1,length(levels(dta$county))), method="srswor")
sample[,2]
#> [1] 1 2 139 223 44 62 162 273 67 203 59 31 244 298 60 200 47 254 397
#> [20] 170 311 277 177 374 153 147 215 104 213 196 121 133 260 345 269 186 188 394
#> [39] 368 233 398 354 252 367 419dtar <- dta[c(1, 94, 216, 204, 211, 58, 162, 15, 55, 203, 59, 362, 247, 404, 41,
87, 399, 113, 303, 243, 73, 358, 411, 374, 175, 147, 215, 104,
213, 372, 150, 133, 174, 250, 280, 308, 355, 395, 257, 233, 387,
248, 252, 367, 420),
c(2, 3, 16, 17)]
head(dtar)
#> county district readscr mathscr
#> 1 Alameda Sunol Glen Unified 691.6 690.0
#> 94 Butte Bangor Union Elementary 646.1 629.8
#> 216 Fresno Alvina Elementary 650.0 660.1
#> 204 San Joaquin Lammersville Elementary 654.1 653.3
#> 211 Kern Kernville Union Elementary 655.1 653.5
#> 58 Sacramento Robla Elementary 637.5 627.0