Move forest plot fun into pkg

- #42 #102 functionalise + document forest plot extraction
- #42 mv plot_forest into pkg and document #102

R/get_forest_plot_data.R

@@ -0,0 +1,90 @@
+#' @title Get Forest Plot Data from a Metafor Model
+#'
+#' @param model A metafor model object of class `rma.mv` or `rma.uni`
+#' @return A tibble containing the data required to plot a forest plot
+#' @export
+#' @family Forest Plot Functions
+#' @examples
+#' get_forest_plot_data(model)
+#' @import broom.mixed
+#' @import dplyr
+#' @import forcats
+#' @import stringr
+get_forest_plot_data <- function(model){
+  model %>% 
+    broom.mixed::tidy(conf.int = TRUE, include_studies = TRUE) %>% 
+    dplyr::mutate(
+      point_shape = 
+        ifelse(stringr::str_detect(term, "overall"), 
+               "diamond", 
+               "circle"),
+      term = 
+        forcats::fct_reorder(term, 
+                             estimate) %>% 
+        forcats::fct_reorder(., 
+                             point_shape,
+                             .desc = TRUE),
+      parameter_type = case_when(str_detect(term, "overall") ~ "mean",
+                                 TRUE ~ "study"),
+      meta_analytic_mean =  pull(., estimate, type) %>% 
+        keep_at(at = "summary")) %>% 
+    select(-type, Parameter = term, everything())
+}
+
+#' @title Plot a Forest Plot
+#' @description Plot a forest plot using the data from `get_forest_plot_data`
+#' @param data A tibble containing the data required to plot a forest plot
+#' @param intercept Logical. Should a horizontal line be added at 0?
+#' @param MA_mean Logical. Should a dashed line be added at the meta-analytic mean?
+#' @return A ggplot object
+#' @export
+#' @import ggplot2
+#' @import ggforestplot
+#' @import NatParksPalettes
+#' @family Forest Plot Functions
+#' @examples
+#' model <- ManyEcoEvo_results %>% pluck("MA_mod", 1) 
+#' plot_data <- get_forest_plot_data(model)
+#' plot_forest(plot_data)
+#' plot_forest(plot_data, intercept = FALSE)
+#' plot_forest(plot_data, MA_mean = FALSE)
+#' plot_forest(plot_data, intercept = FALSE, MA_mean = FALSE)
+plot_forest <- function(data, intercept = TRUE, MA_mean = TRUE){
+  if (MA_mean == FALSE) {
+    data <- filter(data, Parameter != "overall")
+  }
+
+  p <- ggplot(data, aes(y = estimate, 
+                        x =  Parameter, 
+                        ymin = conf.low, 
+                        ymax = conf.high,
+                        shape = point_shape,
+                        colour = parameter_type)) +
+    geom_pointrange(fatten = 2) +
+    ggforestplot::theme_forest() +
+    theme(axis.line = element_line(linewidth = 0.10, colour = "black"),
+          axis.line.y = element_blank(),
+          text = element_text(family = "Helvetica")#,
+          # axis.text.y = element_blank()
+    ) +
+    guides(shape = guide_legend(title = NULL), 
+           colour = guide_legend(title = NULL)) +
+    coord_flip() +
+    ylab(bquote(Standardised~Effect~Size~Z[r])) +
+    xlab(element_blank()) +
+    # scale_y_continuous(breaks = c(-4,-3,-2,-1,0,1),
+    # minor_breaks = seq(from = -4.5, to = 1.5, by = 0.5)) +
+    NatParksPalettes::scale_color_natparks_d("Glacier")
+
+  if (intercept == TRUE) {
+    p <- p + geom_hline(yintercept = 0)
+  }
+  if (MA_mean == TRUE) {
+    p <- p + geom_hline(aes(yintercept = meta_analytic_mean), 
+                        data = data,
+                        colour = "#01353D", 
+                        linetype = "dashed")
+  }
+
+  return(p)
+}