ggplot2 parse =T inside function

Question

I recently did a blog post about adding text to facets in ggplot2 (LINK). I wanted to automate this process a bit so I made the following function. I thought I had great success until I tried to use parse=TRUE. My function is not respecting this argument. How can I use this argument inside my function appropriately as I did in the blog post?

PS I know this isn't exactly minimal but the actual function may be useful to others.

qfacet_text <- function(ggplot2.object, x.coord, y.coord, labels = NULL, 
    text.df = NULL, ...) {
    dat <- ggplot2.object$data
    rows <- ggplot2.object$facet[[1]][[1]]
    cols <- ggplot2.object$facet[[2]][[1]]
    fcol <- dat[, as.character(cols)]
    frow <- dat[, as.character(rows)]
    len <- length(levels(fcol)) *  length(levels(frow))
    vars <- data.frame(expand.grid(levels(frow), levels(fcol)))
    colnames(vars) <- c(as.character(rows), as.character(cols))
    if (is.null(labels)) {
        labels <- LETTERS[1:len]
    }
    if (length(x.coord) == 1) {
       x.coord <- rep(x.coord, len)
    }
    if (length(y.coord) == 1) {
       y.coord <- rep(y.coord, len)
    }
    if (is.null(text.df)) {
        text.df <- data.frame(x = x.coord, y = y.coord, vars, labs=labels)
    } 
    p <- ggplot2.object + geom_text(aes(x, y, label=labs, group=NULL), 
        data=text.df, ...)
    print(p)
    invisible(list(original = ggplot2.object, new = p, dat = text.df))
}

mtcars[, c("cyl", "am", "gear")] <- lapply(mtcars[, c("cyl", "am", "gear")], as.factor)

x <- ggplot(mtcars, aes(mpg, wt, group = cyl)) + 
    geom_line(aes(color=cyl)) +
    geom_point(aes(shape=cyl)) + 
    facet_grid(gear ~ am) +
    theme_bw()  

z <- qfacet_text(x, 33, 2.2, 1:6, color="red")     #as expected
z$dat[5, 1:2] <- c(15, 5)
qfacet_text(x, 33, 2.2, paste("beta ==", 1:6), text.df = z$dat, 
    size = 3, color = "grey50", parse = TRUE)  #doesn't parse

It's interesting that if you try to construct an expression for 'labels', that the error report is: "Error in as.data.frame.default(x[[i]], optional = TRUE) : cannot coerce class '"expression"' into a data.frame" — IRTFM
– IRTFM, Commented Sep 6, 2012 at 21:27

GSee · Accepted Answer · 2012-09-06 21:20:56Z

1

When you call it, don't pass a text.df

qfacet_text(x, 33, 2.2, paste("beta ==", 1:6), text.df = NULL, 
    size = 3, color = "grey50", parse = TRUE)

edited Sep 6, 2012 at 21:20

answered Sep 6, 2012 at 21:13

GSee

50k13 gold badges130 silver badges148 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Tyler Rinker Over a year ago

I did exactly that and the problem is that I just re-fed the data frame from the first plot. Thanks for helping me see that. Bad coding.

Collectives™ on Stack Overflow

ggplot2 parse =T inside function

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related