8 abr. 2018

Intercorrelation between constituents and wavelengths

In the post "Linear Combinations to improve correlation" we selected three wavelengths where normally we found overtones for Protein, Fat and Fiber (Cellulose), and we found a linear combination of these three wavelengths to improve the correlation with the Protein constituent.
In this one we continue with the study of this data set. We have not just the Protein constituent, we have the values for Moisture, Fiber and Fat as well in the "Y" matrix and we want to check the inter-correlation between the constituents.
In the case we have NA values for some sample we won´t get the correlation value, and this is the case, so we remove first the samples with NA values and calculate the correlation between the constituents:


           Protein     Moisture     Fiber       Fat
Protein   1.0000000  0.15406257 -0.83770097 -0.16767249
Moisture  0.1540626  1.00000000 -0.16143400 -0.09022824
Fiber    -0.8377010 -0.16143400  1.00000000  0.07874072
Fat      -0.1676725 -0.09022824  0.07874072  1.00000000

We see how we find a high negative correlation between Fiber and Protein, but this is normal in the case of soy meal.
But do we have high correlation between the absorbance of the wavelengths we associate with Protein and Fiber.

#1022nm  datapoint 87       Protein or Oil
#1008nm  datapoint 80       Oil or Water
# 996nm                     Oil or Water
# 902nm  datapoint 27       Cellulose      
# 964nm  datapoint 58       CH2 Oil       

> cor(X_msc[,87],X_msc[,27])
  [1] -0.9957298
plot(x1,x2,xlab="1022 nm  Protein?",ylab="902 nm Fibre?",
     col="green",main = "cor(X_msc[,87],X_msc[,27])")

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