Library

library(readxl)
library(corrplot)
## corrplot 0.95 loaded

Import Data

data <- read_xls("Concrete_Data.xls")
str(data)
## tibble [1,030 × 9] (S3: tbl_df/tbl/data.frame)
##  $ Cement (component 1)(kg in a m^3 mixture)            : num [1:1030] 540 540 332 332 199 ...
##  $ Blast Furnace Slag (component 2)(kg in a m^3 mixture): num [1:1030] 0 0 142 142 132 ...
##  $ Fly Ash (component 3)(kg in a m^3 mixture)           : num [1:1030] 0 0 0 0 0 0 0 0 0 0 ...
##  $ Water  (component 4)(kg in a m^3 mixture)            : num [1:1030] 162 162 228 228 192 228 228 228 228 228 ...
##  $ Superplasticizer (component 5)(kg in a m^3 mixture)  : num [1:1030] 2.5 2.5 0 0 0 0 0 0 0 0 ...
##  $ Coarse Aggregate  (component 6)(kg in a m^3 mixture) : num [1:1030] 1040 1055 932 932 978 ...
##  $ Fine Aggregate (component 7)(kg in a m^3 mixture)    : num [1:1030] 676 676 594 594 826 ...
##  $ Age (day)                                            : num [1:1030] 28 28 270 365 360 90 365 28 28 28 ...
##  $ Concrete compressive strength(MPa, megapascals)      : num [1:1030] 80 61.9 40.3 41.1 44.3 ...

Preprocessing Data

data_numeric <- data[sapply(data, is.numeric)]

Pada proses ini berfungsi untuk memilih kolom yang berisi numerik karena pada tahap - tahap berikutnya hanya dibutuhkan data numerik aja untuk dianalisis

Correlation Matrix

cor_matrix <- cor(data_numeric, use = "complete.obs")
cor_df <- as.data.frame(round(cor_matrix, 3))
print(cor_df)
##                                                       Cement (component 1)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                 1.000
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                    -0.275
## Fly Ash (component 3)(kg in a m^3 mixture)                                               -0.397
## Water  (component 4)(kg in a m^3 mixture)                                                -0.082
## Superplasticizer (component 5)(kg in a m^3 mixture)                                       0.093
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                     -0.109
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                        -0.223
## Age (day)                                                                                 0.082
## Concrete compressive strength(MPa, megapascals)                                           0.498
##                                                       Blast Furnace Slag (component 2)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                            -0.275
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                                 1.000
## Fly Ash (component 3)(kg in a m^3 mixture)                                                           -0.324
## Water  (component 4)(kg in a m^3 mixture)                                                             0.107
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                   0.043
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                                 -0.284
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                    -0.282
## Age (day)                                                                                            -0.044
## Concrete compressive strength(MPa, megapascals)                                                       0.135
##                                                       Fly Ash (component 3)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                 -0.397
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                     -0.324
## Fly Ash (component 3)(kg in a m^3 mixture)                                                 1.000
## Water  (component 4)(kg in a m^3 mixture)                                                 -0.257
## Superplasticizer (component 5)(kg in a m^3 mixture)                                        0.377
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                      -0.010
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                          0.079
## Age (day)                                                                                 -0.154
## Concrete compressive strength(MPa, megapascals)                                           -0.106
##                                                       Water  (component 4)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                -0.082
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                     0.107
## Fly Ash (component 3)(kg in a m^3 mixture)                                               -0.257
## Water  (component 4)(kg in a m^3 mixture)                                                 1.000
## Superplasticizer (component 5)(kg in a m^3 mixture)                                      -0.657
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                     -0.182
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                        -0.451
## Age (day)                                                                                 0.278
## Concrete compressive strength(MPa, megapascals)                                          -0.290
##                                                       Superplasticizer (component 5)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                           0.093
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                               0.043
## Fly Ash (component 3)(kg in a m^3 mixture)                                                          0.377
## Water  (component 4)(kg in a m^3 mixture)                                                          -0.657
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                 1.000
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                               -0.266
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                   0.223
## Age (day)                                                                                          -0.193
## Concrete compressive strength(MPa, megapascals)                                                     0.366
##                                                       Coarse Aggregate  (component 6)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                           -0.109
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                               -0.284
## Fly Ash (component 3)(kg in a m^3 mixture)                                                          -0.010
## Water  (component 4)(kg in a m^3 mixture)                                                           -0.182
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                 -0.266
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                                 1.000
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                   -0.179
## Age (day)                                                                                           -0.003
## Concrete compressive strength(MPa, megapascals)                                                     -0.165
##                                                       Fine Aggregate (component 7)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                        -0.223
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                            -0.282
## Fly Ash (component 3)(kg in a m^3 mixture)                                                        0.079
## Water  (component 4)(kg in a m^3 mixture)                                                        -0.451
## Superplasticizer (component 5)(kg in a m^3 mixture)                                               0.223
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                             -0.179
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                 1.000
## Age (day)                                                                                        -0.156
## Concrete compressive strength(MPa, megapascals)                                                  -0.167
##                                                       Age (day)
## Cement (component 1)(kg in a m^3 mixture)                 0.082
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)    -0.044
## Fly Ash (component 3)(kg in a m^3 mixture)               -0.154
## Water  (component 4)(kg in a m^3 mixture)                 0.278
## Superplasticizer (component 5)(kg in a m^3 mixture)      -0.193
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)     -0.003
## Fine Aggregate (component 7)(kg in a m^3 mixture)        -0.156
## Age (day)                                                 1.000
## Concrete compressive strength(MPa, megapascals)           0.329
##                                                       Concrete compressive strength(MPa, megapascals)
## Cement (component 1)(kg in a m^3 mixture)                                                       0.498
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                           0.135
## Fly Ash (component 3)(kg in a m^3 mixture)                                                     -0.106
## Water  (component 4)(kg in a m^3 mixture)                                                      -0.290
## Superplasticizer (component 5)(kg in a m^3 mixture)                                             0.366
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                           -0.165
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                              -0.167
## Age (day)                                                                                       0.329
## Concrete compressive strength(MPa, megapascals)                                                 1.000

Correlation matrix digunakan untuk mengidentifikasi hubungan antar variabel dalam dataset sehingga dapat diketahui mana variabel yang saling berkorelasi kuat (positif/negatif). Nilai antar variabel menunjukkan kekuatan hubungan dari -1 (negatif sempurna) hingga +1 (positif sempurna) dengan 0 berarti tidak berkorelasi, sehingga dapat dilihat misalnya Cement berkorelasi kuat positif dengan Superplasticizer dan Water berkorelasi negatif dengan Age yang penting untuk analisis selanjutnya

Visualisasi Correlation Matrix

cor_mat <- as.matrix(cor_df)
corrplot(cor_mat,
         method = "color",
         type = "full",
         addCoef.col = "black",
         number.cex = 0.9,    
         tl.cex = 0.9,       
         tl.srt = 45)

Pada visualisasi tersebut dapat diihat semakin terang warna merah berarti korelasi positif semakin kuat (kedua variabel naik), semakin gelap warna biru berarti korelasi negatif semakin kuat (satu naik satu turun), warna putih/kuning pucat berarti korelasi lemah atau hampir tidak ada hubungan (mendekati 0), dan diagonal selalu merah terang (1.00) karena setiap variabel sempurna berkorelasi dengan dirinya sendiri

Variance-Covariance Matrix

cov_matrix <- cov(data_numeric, use = "complete.obs")
cov_df <- as.data.frame(round(cov_matrix, 2))
print(cov_df)
##                                                       Cement (component 1)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                              10921.74
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                  -2481.36
## Fly Ash (component 3)(kg in a m^3 mixture)                                             -2658.35
## Water  (component 4)(kg in a m^3 mixture)                                               -181.99
## Superplasticizer (component 5)(kg in a m^3 mixture)                                       57.91
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                    -888.61
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                      -1866.15
## Age (day)                                                                                540.99
## Concrete compressive strength(MPa, megapascals)                                          869.15
##                                                       Blast Furnace Slag (component 2)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                          -2481.36
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                               7444.08
## Fly Ash (component 3)(kg in a m^3 mixture)                                                         -1786.61
## Water  (component 4)(kg in a m^3 mixture)                                                            197.68
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                   22.36
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                               -1905.21
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                  -1947.91
## Age (day)                                                                                           -241.15
## Concrete compressive strength(MPa, megapascals)                                                      194.33
##                                                       Fly Ash (component 3)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                               -2658.35
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                   -1786.61
## Fly Ash (component 3)(kg in a m^3 mixture)                                               4095.55
## Water  (component 4)(kg in a m^3 mixture)                                                -351.30
## Superplasticizer (component 5)(kg in a m^3 mixture)                                       144.25
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                      -49.64
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                         405.74
## Age (day)                                                                                -624.06
## Concrete compressive strength(MPa, megapascals)                                          -113.06
##                                                       Water  (component 4)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                               -181.99
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                    197.68
## Fly Ash (component 3)(kg in a m^3 mixture)                                              -351.30
## Water  (component 4)(kg in a m^3 mixture)                                                456.06
## Superplasticizer (component 5)(kg in a m^3 mixture)                                      -83.87
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                    -302.72
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                       -771.57
## Age (day)                                                                                374.50
## Concrete compressive strength(MPa, megapascals)                                         -103.32
##                                                       Superplasticizer (component 5)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                           57.91
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                               22.36
## Fly Ash (component 3)(kg in a m^3 mixture)                                                         144.25
## Water  (component 4)(kg in a m^3 mixture)                                                          -83.87
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                 35.68
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                              -123.69
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                  106.56
## Age (day)                                                                                          -72.72
## Concrete compressive strength(MPa, megapascals)                                                     36.53
##                                                       Coarse Aggregate  (component 6)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                          -888.61
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                             -1905.21
## Fly Ash (component 3)(kg in a m^3 mixture)                                                          -49.64
## Water  (component 4)(kg in a m^3 mixture)                                                          -302.72
## Superplasticizer (component 5)(kg in a m^3 mixture)                                                -123.69
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                               6045.66
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                                 -1112.80
## Age (day)                                                                                           -14.81
## Concrete compressive strength(MPa, megapascals)                                                    -214.23
##                                                       Fine Aggregate (component 7)(kg in a m^3 mixture)
## Cement (component 1)(kg in a m^3 mixture)                                                      -1866.15
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                          -1947.91
## Fly Ash (component 3)(kg in a m^3 mixture)                                                       405.74
## Water  (component 4)(kg in a m^3 mixture)                                                       -771.57
## Superplasticizer (component 5)(kg in a m^3 mixture)                                              106.56
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                           -1112.80
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                               6428.10
## Age (day)                                                                                       -790.57
## Concrete compressive strength(MPa, megapascals)                                                 -224.01
##                                                       Age (day)
## Cement (component 1)(kg in a m^3 mixture)                540.99
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)   -241.15
## Fly Ash (component 3)(kg in a m^3 mixture)              -624.06
## Water  (component 4)(kg in a m^3 mixture)                374.50
## Superplasticizer (component 5)(kg in a m^3 mixture)      -72.72
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)     -14.81
## Fine Aggregate (component 7)(kg in a m^3 mixture)       -790.57
## Age (day)                                               3990.44
## Concrete compressive strength(MPa, megapascals)          347.06
##                                                       Concrete compressive strength(MPa, megapascals)
## Cement (component 1)(kg in a m^3 mixture)                                                      869.15
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)                                          194.33
## Fly Ash (component 3)(kg in a m^3 mixture)                                                    -113.06
## Water  (component 4)(kg in a m^3 mixture)                                                     -103.32
## Superplasticizer (component 5)(kg in a m^3 mixture)                                             36.53
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)                                          -214.23
## Fine Aggregate (component 7)(kg in a m^3 mixture)                                             -224.01
## Age (day)                                                                                      347.06
## Concrete compressive strength(MPa, megapascals)                                                279.08

Variance-covariance matrix digunakan untuk menghitung seberapa variabel-variabel berubah bersamaan dalam dataset. Dimana diagonal menunjukkan varian setiap bahan beton dan elemen off-diagonal menunjukkan bagaimana komposisi bahan saling mempengaruhi

Visualisasi Variance-Covariance Matrix

cov_mat <- as.matrix(cov_df)
corrplot(cov_mat,
         method = "color",
         type = "full",
         addCoef.col = "black",
         number.cex = 0.9,    
         tl.cex = 0.9,          
         tl.srt = 45,
         is.corr = FALSE)

Pada visualisasi tersebut semakin gelap/merah warnanya berarti kovariansi positif semakin besar (variabel berubah searah dengan amplitudo besar), semakin terang/biru muda warnanya berarti kovariansi negatif (variabel berubah berlawanan arah), dan warna paling terang menunjukkan kovariansi mendekati nol (tidak ada hubungan kuat), sedangkan diagonal selalu paling gelap karena menunjukkan varians masing-masing variabel yang tertinggi

eigen_result <- eigen(cov_matrix)
n_pc <- min(8, ncol(data_numeric))

Eigen Value

n_pc <- min(8, ncol(data_numeric))
n_features <- ncol(data_numeric)
eigen_df <- data.frame(
  PC = paste0("PC", 1:n_pc),
  Eigenvalue = round(eigen_result$values[1:n_pc], 3),
  Proportion = round(eigen_result$values[1:n_pc]/sum(eigen_result$values), 3),
  Cumulative = round(cumsum(eigen_result$values[1:n_pc]/sum(eigen_result$values)), 3)
)
print(eigen_df)
##    PC Eigenvalue Proportion Cumulative
## 1 PC1  12897.943      0.325      0.325
## 2 PC2   9825.434      0.248      0.572
## 3 PC3   7287.263      0.184      0.756
## 4 PC4   4247.634      0.107      0.863
## 5 PC5   3986.922      0.100      0.963
## 6 PC6   1268.122      0.032      0.995
## 7 PC7    102.073      0.003      0.998
## 8 PC8     69.746      0.002      1.000

Tabel eigen value menunjukkan besarnya variabilitas data yang tertera pada setiap Principal Component dengan nilai terbesar (PC1) paling penting karena menangkap arah variasi utama dalam data, nilai semakin kecil berarti kontribusi semakin rendah

Eigen Vector

eigen_vec_df <- data.frame(
  row.names = colnames(data_numeric),
  round(eigen_result$vectors[,1:n_pc], 3)
)
colnames(eigen_vec_df) <- paste0("PC", 1:n_pc)
print (eigen_vec_df)
##                                                          PC1    PC2    PC3
## Cement (component 1)(kg in a m^3 mixture)              0.904 -0.023 -0.152
## Blast Furnace Slag (component 2)(kg in a m^3 mixture) -0.255 -0.789 -0.071
## Fly Ash (component 3)(kg in a m^3 mixture)            -0.239  0.299  0.049
## Water  (component 4)(kg in a m^3 mixture)              0.005 -0.075  0.042
## Superplasticizer (component 5)(kg in a m^3 mixture)   -0.001  0.005 -0.024
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)  -0.013  0.276  0.760
## Fine Aggregate (component 7)(kg in a m^3 mixture)     -0.212  0.446 -0.613
## Age (day)                                              0.100 -0.070  0.118
## Concrete compressive strength(MPa, megapascals)        0.067 -0.040 -0.020
##                                                          PC4    PC5    PC6
## Cement (component 1)(kg in a m^3 mixture)              0.013  0.154 -0.277
## Blast Furnace Slag (component 2)(kg in a m^3 mixture)  0.201  0.101 -0.434
## Fly Ash (component 3)(kg in a m^3 mixture)            -0.686  0.188 -0.495
## Water  (component 4)(kg in a m^3 mixture)             -0.076 -0.094  0.468
## Superplasticizer (component 5)(kg in a m^3 mixture)   -0.020  0.023 -0.101
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)   0.479  0.062 -0.275
## Fine Aggregate (component 7)(kg in a m^3 mixture)      0.481 -0.146 -0.256
## Age (day)                                             -0.147 -0.946 -0.204
## Concrete compressive strength(MPa, megapascals)       -0.032 -0.045 -0.279
##                                                          PC7    PC8
## Cement (component 1)(kg in a m^3 mixture)             -0.184  0.155
## Blast Furnace Slag (component 2)(kg in a m^3 mixture) -0.183  0.188
## Fly Ash (component 3)(kg in a m^3 mixture)            -0.194  0.248
## Water  (component 4)(kg in a m^3 mixture)             -0.071  0.833
## Superplasticizer (component 5)(kg in a m^3 mixture)    0.056 -0.222
## Coarse Aggregate  (component 6)(kg in a m^3 mixture)  -0.076  0.173
## Fine Aggregate (component 7)(kg in a m^3 mixture)     -0.102  0.227
## Age (day)                                             -0.113 -0.028
## Concrete compressive strength(MPa, megapascals)        0.926  0.233

Tabel eigen vector menunjukkan bobot relatif setiap variabel komposisi beton (Cement, Water, Age, dll) terhadap PC1-PC8 di mana nilai absolut terbesar menandakan variabel paling dominan pada PC tersebut