What is the index I get from using identify() in a plotted PCA analysis?

[David De la Mora]

Hello.

Using the read.dcd function and then PCA analysis (fit.xyz and pca.xya) on some trajectories, I then plot those results by using plot(pc$z[, 1:2]) and when I use identify() on a point, what is the number I get? I read that it’s an index number, but is it the same as the Frame from my trajectories or is it something different and how can I know and get exactly what it’s referring to? Thank you.

[Xinqiu Yao]

Yes, it is the same as frame no. Type ?identify for more detail.