Editing the Plot
Below, we will make the “Total” row text bold, change the color of
the diamond shape, and modify the background color of the “Total” row.
We will also align the text in the last six columns to the center.
# Change font face
g <- edit_plot(p, row = 9,
gp = gpar(fontface = "bold"))
# Change color
g <- edit_plot(g, col = 8, row = 9, which = "ci",
gp = gpar(col = "blue", fill = "blue"))
# Change the background of the total row
# You need to change both fill and col if you don't want to see a gap between cells
g <- edit_plot(g, col = 1:7,
row = 9,
which = "background",
gp = gpar(fill = "#f6eff7", col = "#f6eff7"))
# Align text to center
g <- edit_plot(g, col = 9:14,
which = "text",
hjust = unit(0.5, "npc"),
x = unit(0.5, "npc"))
g
For text alignment: - hjust = unit(0, "npc") and
x = unit(0, "npc") align text to the left. -
hjust = unit(0.5, "npc") and
x = unit(0.5, "npc") center-align text. -
hjust = unit(1, "npc") and
x = unit(0.9, "npc") align text to the right.
Adding and Inserting Text
In this step, we will add text to the header and display the total
number of events from the data.
# Add or insert some text to the header on top of CI columns
g <- add_text(g, text = "IV, Random, 95% CI",
part = "header",
col = 7:8,
gp = gpar(fontface = "bold"))
g <- insert_text(g, text = "Odds ratio",
part = "header",
col = 7:8,
gp = gpar(fontface = "bold"))
# Group outcomes
g <- add_text(g, text = "Caffeine",
part = "header",
row = 1,
col = 2:3,
gp = gpar(fontface = "bold"))
g <- add_text(g, text = "Decaf",
part = "header",
row = 1,
col = 4:5,
gp = gpar(fontface = "bold"))
# Add text on the top of the risk of bias data
g <- add_text(g, text = "Risk of Bias",
part = "header",
row = 1,
col = 9:14,
gp = gpar(fontface = "bold"))
# Insert event count
g <- insert_text(g,
text = c("Total events:"),
row = 9,
col = 1,
before = FALSE,
just = "left")
# Note: The row counts need to add one to account for
# `insert_text` in the previous step
g <- add_text(g, text = "58",
col = 2,
row = 10,
just = "left")
g <- add_text(g, text = "46",
col = 4,
row = 10,
just = "left")
g
Adding Borders
In this step, we will add borders to the header. By default,
add_border adds a border to the bottom of the specified
cell(s).
# Add or insert some text to the header
g <- add_border(g,
part = "header",
row = 1,
col = 9:14,
gp = gpar(lwd = .5))
g <- add_border(g,
part = "header",
row = 2,
gp = gpar(lwd = 1))
g
Adding Grobs
In the next step, we will add a rounded rectangle with a dashed line
around the risk of bias data. Then, we will draw circle grobs with
different colors at the bottom of the text.
g <- add_grob(g,
row = 1:(nrow(dt_fig) - 1),
col = 9:14,
order = "background",
gb_fn = roundrectGrob,
r = unit(0.05, "snpc"),
gp = gpar(lty = "dotted",
col = "#bdbdbd"))
# Draw a circle grob; you can also draw a `pointsGrob`
cols <- c("#eeee00", "#00cc00", "#cc0000")
symb <- c("?", "+", "-")
for(i in seq_along(symb)){
pos <- which(dt_fig == symb[i], arr.ind = TRUE)
for(j in 1:nrow(pos)){
g <- add_grob(g,
row = pos[j, 1],
col = pos[j, 2],
order = "background",
gb_fn = circleGrob,
r = 0.4,
gp = gpar(fill = cols[i]))
}
}
g
The text we want to create involves math expressions and multiple
lines. While this can be done with add_text by setting
parse = TRUE, we can use the code below to achieve our
desired result. The line break is based on a solution found here,
which uses the atop function. You can also use the latex2exp
package for math expressions.
txt <- bquote(atop(paste("Heterogeneity: ", tau^2, " = 0.22; ",
chi^2, " = 9.39, df = 6 (P = 0.15) ",
I^2, " = 36%"),
"Test for overall effect: Z = 1.15 (P = 0.25)"))
add_text(g, text = txt,
col = 1:6,
row = 11,
just = "left",
parse = TRUE,
gp = gpar(fontsize = 8))
As you can see, the second line is not left-aligned. To address this,
we can use add_grob to leverage other packages that create
grob objects. In this case, we will use the gridtext package
to generate complex text and add it to the plot. More details about this
package can be found here. With
gridtext, you can write and render Markdown or HTML text in
your plot. However, it does not currently support math equations. For
Unicode math symbols, you can refer to this resource here.
txt <- "Heterogeneity: τ<sup>2</sup> = 0.22; χ<sup>2</sup> = 9.39,
df = 6 (P = 0.15); I<sup>2</sup> = 36%<br><span style='color:blue'>**Test for overall effect:**</span> Z = 1.15 (P = 0.25)"
add_grob(g,
row = 11,
col = 1:6,
order = "background",
gb_fn = gridtext::richtext_grob,
text = txt,
gp = gpar(fontsize = 8),
hjust = 0, vjust = 1, halign = 0, valign = 1,
x = unit(0, "npc"), y = unit(1, "npc"))
