# 2-d scatter plot 2-dimension scatter plot. latin1 ```r plotxy(X, group = NULL, asp = 0, col = NULL, alpha.f = .8, zeroes = FALSE, circle = FALSE, ellipse = FALSE, labels = FALSE, legend = TRUE, legend.title = NULL, ncol = 1, ...) ``` ## Arguments - `X`: Data ($n, p$) to plot. If $p > 2$, only the first two columns are considered. - `group`: Groups of observations ($n$) to be plotted with different colors (default to `NULL`). - `asp`: Scalar. Giving the aspect ratio y/x. The value `asp = 0` is the default in `plot.default` (no constraints on the ratio). See `plot.default`. - `col`: A color, or a vector of colors (of length equal to the number of groups), defining the color(s) of the groups. - `alpha.f`: Scalar modifying the opacity of the points in the graphics; typically in [0,1]. See `adjustcolor`. - `zeroes`: Logical indicationg if an horizontal and vertical lines are drawn at coordonates (0, 0) (Default to `FALSE`). - `circle`: Not still working. Logical indicating if a correlation circle is plotted (default to `FALSE`). - `ellipse`: Logical indicating if a Gaussian ellipse is plotted (default to `FALSE`). If there are groups, an ellipse is drawn for each group. - `labels`: Logical indicating if the row names of `X` (instead of points) are plotted (default to `FALSE`). - `legend`: Only if there are groups. Logical indicationg is a legend is drawn for groups (Default to `FALSE`). - `legend.title`: Character string indicationg a title for the legend. - `ncol`: Number of columns drawn in the legend box. - `...`: Other arguments to pass in functions `plot`, `points`, `axis` and `text`. ## Returns A plot. ## Examples ```r n <- 50 ; p <- 10 Xtrain <- matrix(rnorm(n * p), ncol = p) Xtest <- Xtrain[1:5, ] + .4 fm <- pcaeigen(Xtrain, nlv = 5) Ttrain <- fm$T Ttest <- transform(fm, Xtest) T <- rbind(Ttrain, Ttest) group <- c(rep("Training", nrow(Ttrain)), rep("Test", nrow(Ttest))) i <- 1 plotxy(T[, i:(i+1)], group = group, pch = 16, zeroes = TRUE, main = "PCA") plotxy(T[, i:(i+1)], group = group, pch = 16, zeroes = TRUE, asp = 1, main = "PCA") ```

plotxy function