无法更新/编辑从 R 中的包（`gratia`）导出的 ggplot2 对象

Question

我希望我在这里遗漏了一些令人痛苦的明显的东西。

我希望更新（例如，修复标题、实验室等）从gratia::draw(). 不太确定为什么我无法更新该对象。

有一个简单的解决方案吗？

# devtools::install_github('gavinsimpson/gratia')
library('mgcv')
library('gratia')
dat <- gamSim(1, n = 400, dist = "normal", scale = 2, verbose = FALSE)
mod <- gam(y ~ s(x0),  data = dat, method = "REML")
draw(mod)

p = draw(mod)

# P is a ggobject.
class(p)
#> [1] "gg"     "ggplot"

那么，为什么我无法更新p？

p + ggtitle("My title")

^{由reprex 包(v0.2.1)于 2019-02-26 创建}

Answer 1

返回的对象是（不是纯图形对象）draw.gam的输出。 我对 的功能做了一个小小的改变。。现在可以操纵该对象：cowplot::plot_gridggplot2
draw.gamgratia
p

# The modified draw.gam function
mydraw.gam <- function (object, parametric = TRUE, select = NULL, scales = c("free", 
    "fixed"), align = "hv", axis = "lrtb", n = 100, unconditional = FALSE, 
    overall_uncertainty = TRUE, dist = 0.1, ...) 
{
    scales <- match.arg(scales)
    S <- smooths(object)
    select <- gratia:::check_user_select_smooths(smooths = S, select = select)
    d <- gratia:::smooth_dim(object)
    take <- d <= 2L
    select <- select[take]
    S <- S[take]
    d <- d[take]
    is_re <- vapply(object[["smooth"]], gratia:::is_re_smooth, logical(1L))
    is_by <- vapply(object[["smooth"]], gratia:::is_by_smooth, logical(1L))
    if (any(is_by)) {
        S <- vapply(strsplit(S, ":"), `[[`, character(1L), 1L)
    }
    npara <- 0
    nsmooth <- length(S)
    if (isTRUE(parametric)) {
        terms <- parametric_terms(object)
        npara <- length(terms)
        p <- vector("list", length = npara)
    }
    g <- l <- vector("list", length = nsmooth)
    for (i in unique(S)) {
        eS <- evaluate_smooth(object, smooth = i, n = n, unconditional = unconditional, 
            overall_uncertainty = overall_uncertainty, dist = dist)
        l[S == i] <- split(eS, eS[["smooth"]])
    }
    l <- l[select]
    d <- d[select]
    g <- g[select]
    if (length(g) == 0L) {
        message("Unable to draw any of the model terms.")
        return(invisible(g))
    }
    for (i in seq_along(l)) {
        g[[i]] <- draw(l[[i]])
    }
    if (isTRUE(parametric)) {
        for (i in seq_along(terms)) {
            p[[i]] <- evaluate_parametric_term(object, term = terms[i])
            g[[i + length(g)]] <- draw(p[[i]])
        }
    }
    if (isTRUE(identical(scales, "fixed"))) {
        wrapper <- function(x) {
            range(x[["est"]] + (2 * x[["se"]]), x[["est"]] - 
                (2 * x[["se"]]))
        }
        ylims <- range(unlist(lapply(l, wrapper)))
        if (isTRUE(parametric)) {
            ylims <- range(ylims, unlist(lapply(p, function(x) range(x[["upper"]], 
                x[["lower"]]))))
        }
        gg <- seq_along(g)[c(d == 1L, rep(TRUE, npara))]
        for (i in gg) {
            g[[i]] <- g[[i]] + lims(y = ylims)
        }
    }
    g
}

# Example no. 1
dat <- gamSim(1, n = 400, dist = "normal", scale = 2, verbose = FALSE)
mod <- gam(y ~ s(x0),  data = dat, method = "REML")
p <- mydraw.gam(mod)
p[[1]] + ggtitle("My title")

# Example no. 2
mod <- gam(y ~ s(x0) + x1, data = dat, method = "REML")
p <- mydraw.gam(mod)
# Plot graphs separately
p[[1]] + ggtitle("My title")
p[[2]] + ggtitle("My title")
# Arrange the two plots on the same figure
cowplot::plot_grid(plotlist = p)