# To clean environment 
rm(list = ls(all.names = TRUE)) 
gc()
##          used (Mb) gc trigger (Mb) max used (Mb)
## Ncells 518249 27.7    1158588 61.9   644245 34.5
## Vcells 923541  7.1    8388608 64.0  1634757 12.5

Lote

xy<-expand.grid(x=seq(0,19.75,0.25),
                y=seq(0,29.25,0.75))
dim(xy)
## [1] 3200    2
cat("Hileras:",length(seq(0,29.25,0.75)),"\n")
## Hileras: 40
cat("Planta:",length(seq(0,19.75,0.25)))
## Planta: 80
plot(xy,cex=0.5,xlab="Planta",ylab="Hilera",axes=F)

xy2=expand.grid(x=seq(0,19.75,1),
                y=seq(0,29.25,1.5))
plot(xy,cex=0.5,xlab="Planta",ylab="Hilera",axes=F)
points(xy2,col="red",cex=1,pch=15)

Lote 2

set.seed(2023)
enfermedad=round(runif(400,0,0.6),0)
colores=ifelse(enfermedad=="1","red","green")
plot(xy2,xlab="Planta",ylab="Hilera",axes=F,pch=15,col=colores)

Tamaño de muestra para estimar una prevalencia

\[ n=\frac{Np(1-p)}{(N-1)(\frac{e}{Z})^2+p(1-p)} \]

\[ N:\text{400 cuadros}\\ \text{Estudio piloto: 10 cuadros (4/10) = 0.4} \\ \text{p: 0.4} \\ \text{e=5%} \\ \text{Z=1.96} \]

muestran1<-function(N,p,e,z=1.96){
  n=ceiling((N*p*(1-p))/((N-1)*(e/z)^2+p*(1-p)))
  return(n)
}
muestran1(N = 400,p = 0.4,e = 0.08)
## [1] 107
cuadros=sample(400,107,replace = F)
plot(xy2,xlab="Planta",ylab="Hilera",axes=F,pch=15,col=colores)
points(xy2[cuadros,],pch=0,cex=2)

table(colores[cuadros])
## 
## green   red 
##    89    18
14/107*100
## [1] 13.08411
table(colores)
## colores
## green   red 
##   329    71
55/400*100
## [1] 13.75

Dependencia espacial

enfermedad2=sort.int(round(runif(400,0,0.6),0),partial = 200)
colores2=ifelse(enfermedad2=="1","red","green")
plot(xy2,xlab="Planta",ylab="Hilera",axes=F,pch=15,col=colores2)
points(xy2[cuadros,],pch=0,cex=2)

cuadros=sample(400,107,replace = F)
plot(xy2,xlab="Planta",ylab="Hilera",axes=F,pch=15,col=colores2)
titulo=table(colores2[cuadros])[2]/107
titulo=round(titulo,3)
points(xy2[cuadros,],pch=0,cex=2)
text(5,1,titulo,cex=3)

Muestreo espacial

set.seed(2023)
enfermedad2=(runif(400,0,0.6))
enfermedad2_round=sort.int(round(enfermedad2,0),partial = 200)
NDVI=1-enfermedad2
df=data.frame(xy2,enfermedad=enfermedad2_round)
df$NDVI=NDVI
library(ggplot2)
df |> 
  ggplot(aes(x,y,fill=NDVI))+
  geom_tile()+
  scale_fill_gradientn(colors = hcl.colors(20, "RdYlGn"))

df
##      x    y enfermedad      NDVI
## 1    0  0.0          0 0.7200316
## 2    1  0.0          0 0.7988854
## 3    2  0.0          0 0.9023095
## 4    3  0.0          0 0.7623280
## 5    4  0.0          0 0.9817650
## 6    5  0.0          0 0.9274691
## 7    6  0.0          0 0.7443006
## 8    7  0.0          0 0.6292853
## 9    8  0.0          0 0.8420750
## 10   9  0.0          0 0.7142057
## 11  10  0.0          0 0.4826086
## 12  11  0.0          0 0.9106728
## 13  12  0.0          0 0.8917420
## 14  13  0.0          0 0.4004360
## 15  14  0.0          0 0.4949553
## 16  15  0.0          0 0.9144106
## 17  16  0.0          0 0.7930910
## 18  17  0.0          0 0.4662247
## 19  18  0.0          0 0.8080910
## 20  19  0.0          0 0.5745905
## 21   0  1.5          0 0.6231090
## 22   1  1.5          0 0.7370965
## 23   2  1.5          0 0.7960624
## 24   3  1.5          0 0.4401444
## 25   4  1.5          0 0.5722274
## 26   5  1.5          0 0.6214889
## 27   6  1.5          0 0.5521303
## 28   7  1.5          0 0.9331298
## 29   8  1.5          0 0.8360269
## 30   9  1.5          0 0.9408891
## 31  10  1.5          0 0.5454823
## 32  11  1.5          0 0.6018447
## 33  12  1.5          0 0.5653833
## 34  13  1.5          0 0.7246321
## 35  14  1.5          0 0.5953609
## 36  15  1.5          0 0.5796918
## 37  16  1.5          0 0.5109567
## 38  17  1.5          0 0.5852911
## 39  18  1.5          0 0.5701526
## 40  19  1.5          0 0.4656521
## 41   0  3.0          0 0.7958219
## 42   1  3.0          0 0.5988623
## 43   2  3.0          0 0.7694476
## 44   3  3.0          0 0.8589320
## 45   4  3.0          0 0.4669018
## 46   5  3.0          0 0.5191290
## 47   6  3.0          0 0.6421434
## 48   7  3.0          0 0.4137894
## 49   8  3.0          0 0.8031370
## 50   9  3.0          0 0.5168920
## 51  10  3.0          0 0.9806108
## 52  11  3.0          0 0.7310261
## 53  12  3.0          0 0.8411610
## 54  13  3.0          0 0.7544395
## 55  14  3.0          0 0.8832419
## 56  15  3.0          0 0.6739075
## 57  16  3.0          0 0.4389378
## 58  17  3.0          0 0.5355774
## 59  18  3.0          0 0.4018700
## 60  19  3.0          0 0.5064245
## 61   0  4.5          0 0.7649768
## 62   1  4.5          0 0.7688503
## 63   2  4.5          0 0.4605173
## 64   3  4.5          0 0.8086882
## 65   4  4.5          0 0.8747869
## 66   5  4.5          0 0.6614937
## 67   6  4.5          0 0.7107493
## 68   7  4.5          0 0.9609312
## 69   8  4.5          0 0.8432336
## 70   9  4.5          0 0.8017986
## 71  10  4.5          0 0.8016615
## 72  11  4.5          0 0.9445880
## 73  12  4.5          0 0.5836039
## 74  13  4.5          0 0.9301062
## 75  14  4.5          0 0.4776416
## 76  15  4.5          0 0.9227976
## 77  16  4.5          0 0.4987732
## 78  17  4.5          0 0.8573849
## 79  18  4.5          0 0.7297488
## 80  19  4.5          0 0.4994208
## 81   0  6.0          0 0.6005218
## 82   1  6.0          0 0.6735285
## 83   2  6.0          0 0.6026248
## 84   3  6.0          0 0.4758926
## 85   4  6.0          0 0.5989672
## 86   5  6.0          0 0.8718728
## 87   6  6.0          0 0.7485554
## 88   7  6.0          0 0.7223344
## 89   8  6.0          0 0.6287148
## 90   9  6.0          0 0.7097643
## 91  10  6.0          0 0.5462374
## 92  11  6.0          0 0.8670329
## 93  12  6.0          0 0.4052923
## 94  13  6.0          0 0.4121623
## 95  14  6.0          0 0.4845822
## 96  15  6.0          0 0.8550915
## 97  16  6.0          0 0.6212005
## 98  17  6.0          0 0.5535726
## 99  18  6.0          0 0.5353578
## 100 19  6.0          0 0.5950981
## 101  0  7.5          0 0.5519329
## 102  1  7.5          0 0.4155447
## 103  2  7.5          0 0.9174026
## 104  3  7.5          0 0.5527489
## 105  4  7.5          0 0.7982613
## 106  5  7.5          0 0.6113750
## 107  6  7.5          0 0.4709950
## 108  7  7.5          0 0.7429064
## 109  8  7.5          0 0.4339017
## 110  9  7.5          0 0.8483439
## 111 10  7.5          0 0.4067671
## 112 11  7.5          0 0.4563267
## 113 12  7.5          0 0.9883361
## 114 13  7.5          0 0.6679686
## 115 14  7.5          0 0.7950426
## 116 15  7.5          0 0.6215738
## 117 16  7.5          0 0.6290210
## 118 17  7.5          0 0.4462353
## 119 18  7.5          0 0.5458135
## 120 19  7.5          0 0.8485441
## 121  0  9.0          0 0.4969188
## 122  1  9.0          0 0.7367644
## 123  2  9.0          0 0.7670914
## 124  3  9.0          0 0.6076849
## 125  4  9.0          0 0.9836284
## 126  5  9.0          0 0.7682341
## 127  6  9.0          0 0.9278478
## 128  7  9.0          0 0.9104233
## 129  8  9.0          0 0.4889064
## 130  9  9.0          0 0.5073020
## 131 10  9.0          0 0.7317249
## 132 11  9.0          0 0.4710453
## 133 12  9.0          0 0.5194538
## 134 13  9.0          0 0.7159342
## 135 14  9.0          0 0.7869411
## 136 15  9.0          0 0.5468291
## 137 16  9.0          0 0.4884491
## 138 17  9.0          0 0.9406117
## 139 18  9.0          0 0.5064249
## 140 19  9.0          0 0.5107286
## 141  0 10.5          0 0.9582263
## 142  1 10.5          0 0.8529337
## 143  2 10.5          0 0.8931408
## 144  3 10.5          0 0.8222180
## 145  4 10.5          0 0.7202983
## 146  5 10.5          0 0.9511637
## 147  6 10.5          0 0.8841368
## 148  7 10.5          0 0.8319196
## 149  8 10.5          0 0.5498947
## 150  9 10.5          0 0.8631014
## 151 10 10.5          0 0.7192970
## 152 11 10.5          0 0.9605912
## 153 12 10.5          0 0.7299837
## 154 13 10.5          0 0.8979451
## 155 14 10.5          0 0.7906687
## 156 15 10.5          0 0.6685974
## 157 16 10.5          0 0.6959723
## 158 17 10.5          0 0.7250607
## 159 18 10.5          0 0.9219893
## 160 19 10.5          0 0.9418314
## 161  0 12.0          0 0.6481465
## 162  1 12.0          0 0.9789451
## 163  2 12.0          0 0.4243982
## 164  3 12.0          0 0.6187641
## 165  4 12.0          0 0.7285549
## 166  5 12.0          0 0.6285423
## 167  6 12.0          0 0.5880519
## 168  7 12.0          0 0.5601844
## 169  8 12.0          0 0.6662736
## 170  9 12.0          0 0.7181087
## 171 10 12.0          0 0.6274321
## 172 11 12.0          0 0.5486793
## 173 12 12.0          0 0.4960550
## 174 13 12.0          0 0.7186421
## 175 14 12.0          0 0.8186231
## 176 15 12.0          0 0.7625492
## 177 16 12.0          0 0.8741236
## 178 17 12.0          0 0.4465987
## 179 18 12.0          0 0.9836627
## 180 19 12.0          0 0.8721779
## 181  0 13.5          0 0.9505628
## 182  1 13.5          0 0.7884249
## 183  2 13.5          0 0.6004490
## 184  3 13.5          0 0.6827622
## 185  4 13.5          0 0.7693225
## 186  5 13.5          0 0.4879164
## 187  6 13.5          0 0.4067823
## 188  7 13.5          0 0.4720570
## 189  8 13.5          0 0.9267349
## 190  9 13.5          0 0.9205644
## 191 10 13.5          0 0.4643964
## 192 11 13.5          0 0.4465277
## 193 12 13.5          0 0.9595322
## 194 13 13.5          0 0.7876535
## 195 14 13.5          0 0.7549539
## 196 15 13.5          0 0.9328916
## 197 16 13.5          0 0.8771658
## 198 17 13.5          0 0.9725726
## 199 18 13.5          0 0.9443663
## 200 19 13.5          0 0.8802405
## 201  0 15.0          0 0.6811065
## 202  1 15.0          0 0.4575390
## 203  2 15.0          0 0.7260967
## 204  3 15.0          0 0.6441469
## 205  4 15.0          0 0.5095562
## 206  5 15.0          0 0.5312106
## 207  6 15.0          0 0.4988123
## 208  7 15.0          0 0.8791675
## 209  8 15.0          0 0.5036915
## 210  9 15.0          0 0.7019407
## 211 10 15.0          0 0.7040625
## 212 11 15.0          0 0.8005281
## 213 12 15.0          0 0.8588374
## 214 13 15.0          0 0.5334699
## 215 14 15.0          0 0.6291293
## 216 15 15.0          0 0.6696113
## 217 16 15.0          0 0.8900609
## 218 17 15.0          0 0.9940549
## 219 18 15.0          0 0.4495690
## 220 19 15.0          0 0.9027125
## 221  0 16.5          0 0.5508791
## 222  1 16.5          0 0.5914100
## 223  2 16.5          0 0.6985297
## 224  3 16.5          0 0.4078756
## 225  4 16.5          0 0.6372644
## 226  5 16.5          0 0.7268559
## 227  6 16.5          0 0.9882118
## 228  7 16.5          0 0.7429919
## 229  8 16.5          0 0.5354391
## 230  9 16.5          0 0.7143692
## 231 10 16.5          0 0.6977445
## 232 11 16.5          0 0.8070706
## 233 12 16.5          0 0.9055081
## 234 13 16.5          0 0.4899944
## 235 14 16.5          0 0.4029705
## 236 15 16.5          0 0.6198562
## 237 16 16.5          0 0.5449326
## 238 17 16.5          0 0.6082246
## 239 18 16.5          0 0.4180636
## 240 19 16.5          0 0.9708749
## 241  0 18.0          0 0.8095771
## 242  1 18.0          0 0.4443345
## 243  2 18.0          0 0.6138441
## 244  3 18.0          0 0.9078180
## 245  4 18.0          0 0.6752602
## 246  5 18.0          0 0.9352995
## 247  6 18.0          0 0.6187258
## 248  7 18.0          0 0.5050656
## 249  8 18.0          0 0.8673189
## 250  9 18.0          0 0.9791040
## 251 10 18.0          0 0.4815122
## 252 11 18.0          0 0.8719643
## 253 12 18.0          0 0.8537876
## 254 13 18.0          0 0.5494490
## 255 14 18.0          0 0.7484807
## 256 15 18.0          0 0.5051774
## 257 16 18.0          0 0.7775282
## 258 17 18.0          0 0.6304703
## 259 18 18.0          0 0.4633113
## 260 19 18.0          0 0.8153953
## 261  0 19.5          0 0.7288209
## 262  1 19.5          0 0.9797029
## 263  2 19.5          0 0.4049439
## 264  3 19.5          0 0.8140072
## 265  4 19.5          0 0.6172148
## 266  5 19.5          0 0.5052566
## 267  6 19.5          0 0.5023892
## 268  7 19.5          0 0.4430282
## 269  8 19.5          1 0.7743460
## 270  9 19.5          1 0.5522531
## 271 10 19.5          1 0.4564995
## 272 11 19.5          1 0.6989168
## 273 12 19.5          0 0.9802165
## 274 13 19.5          1 0.9960366
## 275 14 19.5          1 0.5576457
## 276 15 19.5          0 0.8420013
## 277 16 19.5          1 0.7429689
## 278 17 19.5          1 0.4731265
## 279 18 19.5          1 0.6110653
## 280 19 19.5          0 0.5050032
## 281  0 21.0          0 0.7546056
## 282  1 21.0          0 0.8936010
## 283  2 21.0          1 0.7363628
## 284  3 21.0          0 0.5557145
## 285  4 21.0          1 0.5479127
## 286  5 21.0          1 0.9550122
## 287  6 21.0          1 0.9753562
## 288  7 21.0          1 0.8914682
## 289  8 21.0          0 0.6999893
## 290  9 21.0          0 0.5035729
## 291 10 21.0          1 0.5726642
## 292 11 21.0          1 0.4690844
## 293 12 21.0          0 0.6142686
## 294 13 21.0          1 0.4247378
## 295 14 21.0          0 0.6638275
## 296 15 21.0          1 0.4433054
## 297 16 21.0          1 0.7270671
## 298 17 21.0          0 0.9387862
## 299 18 21.0          1 0.8177948
## 300 19 21.0          0 0.7378482
## 301  0 22.5          0 0.5940933
## 302  1 22.5          0 0.9036134
## 303  2 22.5          1 0.4020511
## 304  3 22.5          1 0.8731396
## 305  4 22.5          0 0.9274621
## 306  5 22.5          1 0.5121712
## 307  6 22.5          1 0.5065578
## 308  7 22.5          1 0.4800592
## 309  8 22.5          0 0.8396761
## 310  9 22.5          1 0.7045629
## 311 10 22.5          0 0.5061806
## 312 11 22.5          1 0.6410605
## 313 12 22.5          1 0.6105176
## 314 13 22.5          1 0.4080372
## 315 14 22.5          0 0.6996030
## 316 15 22.5          1 0.7558936
## 317 16 22.5          0 0.5347690
## 318 17 22.5          1 0.4722249
## 319 18 22.5          1 0.4333411
## 320 19 22.5          0 0.6125484
## 321  0 24.0          1 0.4254527
## 322  1 24.0          0 0.9907744
## 323  2 24.0          1 0.6232289
## 324  3 24.0          1 0.9328105
## 325  4 24.0          1 0.5819798
## 326  5 24.0          1 0.9791117
## 327  6 24.0          0 0.5271119
## 328  7 24.0          0 0.8388896
## 329  8 24.0          0 0.8959708
## 330  9 24.0          1 0.7410447
## 331 10 24.0          0 0.6184414
## 332 11 24.0          1 0.9391587
## 333 12 24.0          0 0.7278865
## 334 13 24.0          0 0.5968180
## 335 14 24.0          0 0.7191339
## 336 15 24.0          0 0.7802721
## 337 16 24.0          1 0.6340180
## 338 17 24.0          1 0.4129652
## 339 18 24.0          0 0.7017871
## 340 19 24.0          0 0.7273099
## 341  0 25.5          0 0.5905491
## 342  1 25.5          1 0.4753150
## 343  2 25.5          1 0.6306410
## 344  3 25.5          0 0.6269294
## 345  4 25.5          1 0.8818662
## 346  5 25.5          1 0.8643861
## 347  6 25.5          0 0.9801322
## 348  7 25.5          0 0.8072534
## 349  8 25.5          0 0.9194519
## 350  9 25.5          0 0.6410174
## 351 10 25.5          1 0.8127032
## 352 11 25.5          0 0.9343114
## 353 12 25.5          1 0.4140649
## 354 13 25.5          0 0.6903738
## 355 14 25.5          0 0.9431428
## 356 15 25.5          0 0.5312064
## 357 16 25.5          0 0.8219999
## 358 17 25.5          1 0.4811872
## 359 18 25.5          1 0.4723134
## 360 19 25.5          1 0.4514776
## 361  0 27.0          0 0.6877531
## 362  1 27.0          1 0.4939148
## 363  2 27.0          0 0.6986776
## 364  3 27.0          1 0.7585079
## 365  4 27.0          0 0.5017487
## 366  5 27.0          0 0.5500370
## 367  6 27.0          1 0.6425234
## 368  7 27.0          0 0.9536470
## 369  8 27.0          1 0.9076285
## 370  9 27.0          0 0.5449850
## 371 10 27.0          0 0.5031301
## 372 11 27.0          1 0.9955066
## 373 12 27.0          0 0.7838334
## 374 13 27.0          0 0.9964805
## 375 14 27.0          0 0.5351420
## 376 15 27.0          0 0.7348855
## 377 16 27.0          0 0.6690337
## 378 17 27.0          1 0.6586328
## 379 18 27.0          0 0.8642931
## 380 19 27.0          1 0.4065435
## 381  0 28.5          1 0.6367477
## 382  1 28.5          1 0.5316251
## 383  2 28.5          1 0.7756326
## 384  3 28.5          1 0.9151380
## 385  4 28.5          1 0.8971336
## 386  5 28.5          1 0.5556333
## 387  6 28.5          0 0.8584752
## 388  7 28.5          0 0.8680335
## 389  8 28.5          1 0.8335562
## 390  9 28.5          1 0.8280266
## 391 10 28.5          1 0.4458492
## 392 11 28.5          1 0.4650102
## 393 12 28.5          1 0.4224210
## 394 13 28.5          1 0.5331979
## 395 14 28.5          0 0.5858987
## 396 15 28.5          0 0.9318912
## 397 16 28.5          1 0.4359596
## 398 17 28.5          1 0.8884903
## 399 18 28.5          0 0.6081885
## 400 19 28.5          0 0.8519536

Muestreo espacial

5*400/100
## [1] 20
library(clhs)
res <- clhs(df[,c(1,2)], size = 12, progress = FALSE, simple = TRUE)
plot(df$x,df$y)
points(df$x[res],df$y[res],pch=16)

res2 <- clhs(df, size = 12, progress = FALSE, simple = TRUE)
plot(df$x,df$y)
points(df$x[res2],df$y[res2],pch=16)

res3 <- clhs(xy, size = 20, progress = FALSE, simple = TRUE)
plot(xy,cex=0.6)
points(xy$x[res3],xy$y[res3],pch=16,cex=1)