---
title: "B. Basic analysis"
output:
rmarkdown::html_vignette:
toc: true
vignette: >
%\VignetteIndexEntry{B. Basic analysis}
%\VignetteEncoding{UTF-8}
%\VignetteEngine{knitr::rmarkdown}
editor_options:
chunk_output_type: console
---
```{r, include = FALSE}
knitr::opts_chunk$set(
collapse = TRUE,
comment = "#>",
fig.width=6,
fig.height=4
)
# Legge denne i YAML på toppen for å skrive ut til tex
#output:
# pdf_document:
# keep_tex: true
# Original:
# rmarkdown::html_vignette:
# toc: true
```
```{r setup}
# Start the multiblock R package
library(multiblock)
```
# Basic methods
The following single- and two-block methods are available in the _multiblock_ package (function names in parentheses):
* PCA - Principal Component Analysis (_pca_)
* PCR - Principal Component Regression (_pcr_)
* PLSR - Partial Least Squares Regression (_plsr_)
* CCA - Canonical Correlation Analysis (_cca_)
* IFA - Interbattery Factor Analysis (_ifa_)
* GSVD - Generalized SVD (_gsvd_)
The following sections will describe how to format your data for analysis and invoke all methods from the list above.
## Prepare data
We use a selection of extracts from the potato data included in the package for the basic data analyses. The
data set is stored as a named list of nine matrices with chemical, rheological, spectral and sensory measurements with measurements from 26 raw and cooked potatoes.
```{r}
data(potato)
X <- potato$Chemical
y <- potato$Sensory[,1,drop=FALSE]
```
## Modelling
Since the basic methods cover both single block analysis, supervised and unsupervised analysis, the interfaces
for the basic methods vary a bit. Supervised methods use the formula interface and the remaining methods take
input as a single matrix or list of matrices. See vignettes for supervised and unsupervised analysis for details.
```{r}
# Single block
pot.pca <- pca(X, ncomp = 2)
# Two blocks, supervised
pot.pcr <- pcr(y ~ X, ncomp = 2)
pot.pls <- plsr(y ~ X, ncomp = 2)
# Two blocks, unsupervised
pot.cca <- cca(potato[1:2])
pot.ifa <- ifa(potato[1:2])
# Variable linked decomposition
pot.gsvd <- gsvd(lapply(potato[3:4], t))
```
## Common output elements across methods
Output from all methods include matrices called _loadings_, _scores_, _blockLoadings_
and _blockScores_, or a suitable subset of these according the method used. An _info_ list describes which
types of (block) loadings/scores are in the output. There may be various extra
elements in addition to the common elements, e.g. coefficients, weights etc. The _names()_ and _summary()_ functions below show all elements of the object and a summary based on the _info_ list, respectively.
```{r}
# PCA returns loadings and scores:
names(pot.pca)
summary(pot.pca)
# GSVD returns block scores and common loadings:
names(pot.gsvd)
summary(pot.gsvd)
```
## Scores and loadings
Functions for accessing scores and loadings are based on functions
from the _pls_ package, but extended with a _block_ parameter to
allow extraction of common/global scores/loadings and their block
counterparts. The default value for _block_ is 0, corresponding to the common/global
block. Block scores/loadings can be accessed by setting _block_ to a number or name.
```{r}
# Global scores plotted with object labels
scoreplot(pot.pca, labels = "names")
```
```{r}
# Block loadings for Chemical block with variable labels in scatter format
loadingplot(pot.cca, block = "Chemical", labels = "names")
```
```{r}
# Non-existing elements are swapped with existing ones with a warning.
sc <- scores(pot.cca)
```