ANALISIS DE COMPONENTES PRINCIPALES

library(readxl)
corredores<-read_excel("C:/Users/MINEDUCYT/Desktop/corredores.xlsx")
corredores
# A tibble: 12 × 4
   `km 4` `km 8` `km 12` `km 16`
    <dbl>  <dbl>   <dbl>   <dbl>
 1     10     10      13      12
 2     12     12      14      15
 3     11     10      14      13
 4      9      9      11      11
 5      8      8       9       8
 6      8      9      10       9
 7     10     10       8       9
 8     11     12      10       9
 9     14     13      11      11
10     12     12      12      10
11     13     13      11      11
12     14     15      14      13
library(FactoMineR)
componentes <- PCA(corredores, graph = FALSE)
componentes$eig
       eigenvalue percentage of variance cumulative percentage of variance
comp 1 2.88618524              72.154631                          72.15463
comp 2 0.96729411              24.182353                          96.33698
comp 3 0.10217301               2.554325                          98.89131
comp 4 0.04434764               1.108691                         100.00000

Calculando las componentes.

coef_PC1 <- componentes$var$coord[, 1]
coef_PC1
     km 4      km 8     km 12     km 16 
0.8776220 0.8407308 0.8342672 0.8444731 
PC1 <- as.matrix(corredores)%*%coef_PC1
PC1
          [,1]
 [1,] 38.16268
 [2,] 44.96707
 [3,] 40.71904
 [4,] 33.93132
 [5,] 28.01101
 [6,] 30.53048
 [7,] 31.45792
 [8,] 35.68554
 [9,] 41.68235
[10,] 39.07617
[11,] 40.80473
[12,] 47.55556
coef_PC2 <- componentes$var$coord[, 2]
coef_PC2
      km 4       km 8      km 12      km 16 
-0.4521406 -0.5193155  0.5049832  0.4880229 
PC2 <- as.matrix(corredores)%*%coef_PC2
PC2
            [,1]
 [1,]  2.7064950
 [2,]  2.7326345
 [3,]  3.2473605
 [4,]  2.1799618
 [5,]  0.6773829
 [6,]  1.1510735
 [7,] -1.2824897
 [8,] -1.7632949
 [9,] -2.1580033
[10,] -0.7174462
[11,] -1.7058627
[12,] -0.7056390
coef_PC3<-componentes$var$coord[,3]
coef_PC3
       km 4        km 8       km 12       km 16 
-0.06246401  0.06458405  0.21853379 -0.21527457 
coef_PC4<-componentes$var$coord[,4]
coef_PC4
       km 4        km 8       km 12       km 16 
-0.14644697  0.13896759 -0.03511663  0.04853608 
var_corredores<-var(corredores)
corr_corredores<-cor(corredores)
egenval<-eigen(corr_corredores)
egenval
eigen() decomposition
$values
[1] 2.88618524 0.96729411 0.10217301 0.04434764

$vectors
           [,1]       [,2]       [,3]       [,4]
[1,] -0.5165893  0.4597209  0.1954167  0.6954168
[2,] -0.4948743  0.5280220 -0.2020492 -0.6599002
[3,] -0.4910696 -0.5134494 -0.6836763  0.1667545
[4,] -0.4970771 -0.4962047  0.6734799 -0.2304780
var_explicada<-100*(sum(egenval$values[1:2])/sum(egenval$values[1:4]))
var_explicada
[1] 96.33698
pca1 <- prcomp(corredores, scale = T)
pca1
Standard deviations (1, .., p=4):
[1] 1.6988776 0.9835111 0.3196451 0.2105888

Rotation (n x k) = (4 x 4):
            PC1        PC2        PC3        PC4
km 4  0.5165893  0.4597209  0.1954167  0.6954168
km 8  0.4948743  0.5280220 -0.2020492 -0.6599002
km 12 0.4910696 -0.5134494 -0.6836763  0.1667545
km 16 0.4970771 -0.4962047  0.6734799 -0.2304780
summary(pca1)
Importance of components:
                          PC1    PC2     PC3     PC4
Standard deviation     1.6989 0.9835 0.31965 0.21059
Proportion of Variance 0.7216 0.2418 0.02554 0.01109
Cumulative Proportion  0.7216 0.9634 0.98891 1.00000
pca1$rotation[, 1:2]
            PC1        PC2
km 4  0.5165893  0.4597209
km 8  0.4948743  0.5280220
km 12 0.4910696 -0.5134494
km 16 0.4970771 -0.4962047
biplot(pca1, cex = c(0.01, 1), scale = 0.2, xlim=c(-2,2),ylim = c(-2, 2))
points(x = pca1$x[,1], y = pca1$x[,2], cex = 1, pch=19,col = "blue")