pca_contrib_plot {nzilbb.vowels} | R Documentation |
PCA contribution plots
Description
Plot the contribution of each variable in a data set to a given Principal Component (PC). Variables are arranged by ascending contribution to the PC, where contribution is the squared loading for the variable expressed as a percentage. These plots match those given in supplementary material for Brand et al. (2021).
Usage
pca_contrib_plot(pca_object, pc_no = 1, cutoff = 50)
Arguments
pca_object |
a pca object generated by |
pc_no |
the PC to be visualised. Default value is 1. |
cutoff |
the cutoff value for interpretation of the PC. Determines what
total percentage contribution we want from the variables we select for
interpretation. The default of 50 means that we pick the variables with the
highest contribution to the PC until we have accounted for 50% of the total
contributions to the PC. Can be set to |
Details
As with the other plotting functions in this package, the result is a
ggplot2
plot. It can be modified using ggplot2
functions (see, e.g.,
plot_correlation_magnitudes()
.
Value
ggplot
object.
References
Brand, James, Jen Hay, Lynn Clark, Kevin Watson & Márton Sóskuthy (2021): Systematic co-variation of monophthongs across speakers of New Zealand English. Journal of Phonetics. Elsevier. 88. 101096. doi:10.1016/j.wocn.2021.101096
Examples
onze_pca <- prcomp(onze_intercepts |> dplyr::select(-speaker), scale = TRUE)
# Plot PC1 with a cutoff value of 60%
pca_contrib_plot(onze_pca, pc_no = 1, cutoff = 60)
# Plot PC2 with no cutoff value.
pca_contrib_plot(onze_pca, pc_no = 2, cutoff = NULL)