Articles by jrcuesta

Looking to boxplots (Shootout 2012)

January 20, 2013 | jrcuesta

Boxplots are a nice way to compare the three sample sets of the Shoot-out 2012 data files.There is a category variable (Set) in the data frame with the labels (Cal = Training Set, Test = Test Set and Val = Validation Set). # IMPORTING THE SAMPLE SETS #... [Read more...]

Standard Normal Variate (SNV: Other way)

January 1, 2013 | jrcuesta

This is another way to pre-treat aspectra set with the SNV math-treatment (Standard Normal Variate). You can see the other one in the post : "Standard Normal Variate (SNV)".In this post, I use the R function "sweep".library(ChemometricsWithR)#in a... [Read more...]

"R" : Identifying peaks

December 13, 2012 | jrcuesta

The function "identify"  from "R",  is very useful to check the spectrum for peaks or areas of interest. I use it here to see the wavelength with the highest variability in the Shootout-2012 Calibration Set. This wavelength has a high variabi...
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Shootout 2012 : first PLS regressions

November 23, 2012 | jrcuesta

It´s time to start developing some regressions in order to find the best math treatment, the best number of terms, the best spectral regions, the best regression method,....This time I´m working with the PLS  package in R, and just to make ...
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Shootout 2012: Test & Val Sets proyections

November 7, 2012 | jrcuesta

It is obvious (after seeing the spectra of the calibration set), that we have at least three clusters, and that this can be related with the concentration of the active ingredient in the tablets. If we see the scores in the PC1-PC2 score map we will se...
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Working with Shootout – 2012 in R (001)

October 29, 2012 | jrcuesta

I have downloaded (from the IDRC) the ASCI files of the Shootout 2012 (see: Shootout 2012 files), so I can work with the data  to develop a model and predict a Validation Set.For that task I have a "Calibration Set", and a  "Test Se...
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Looking to the PCA scores with GGobi

October 21, 2012 | jrcuesta

In this post I continue with the unsupervised exploration of oil spectra, which we have seen in previous post ( PCA with "ChemoSpec" - 001).In the manual "ChemoSpec:An R Package for Chemometric Analysis of Spectroscopic Data", (page 23) there is a brie...
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PCA with "ChemoSpec" – 001

October 20, 2012 | jrcuesta

In my last post about "ChemoSpec package" (Hierarchical Cluster Analysis (ChemoSpec) - 02), we saw the two cluster groups (one for olive oil, other for sunflower oil), and also another sub-clusters for the sunflower oil.Continue reading the manual "Che...
[Read more...]

PLS2 with "R"

September 22, 2012 | jrcuesta

I´ve been working these days with PLS2 calibrations with a chemometric software called “Unscrambler” with a data set called “jam”. I said “can I develop PLS2 models with R?”.I look in the book “Introduction to Multivariate Statistical An...
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Monitor: Using category labels

July 26, 2012 | jrcuesta

I´ve been checking recently the performance of a calibration of compound feed with  a set of samples (15): 3 samples of hen feed, 3 of pig feed, 3 of chicken feed, 3 of ovine feed and 3 of cattle feed.The idea is to check if the calibration predi...
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