ggplot legend not filled

0
votes

I'm having difficulty modifying the legends on my ggplot to plot to my liking.

  1. The correct fill is not showing (the circles are all black atm, so I can't tel which group the points refer to)
  2. The position is incorrect (position = "bottom" is not working)
  3. Ideally, I would like the legends to use squares (the same as the shape used in my plot) rather than circles, but I'm not sure how to achieve this.

My data:

ors_fi = structure(list(col.x = c("Pre-frail", "Frail", "Pre-frail", "Frail", 
"Pre-frail", "Frail"), col.estimate = c(0.865018872113144, 1.63924006466768, 
0.972589483876898, 1.74300310363782, 0.836325226050668, 1.51301774619739
), col.stderr = c(0.0865502520576455, 0.0991158308454572, 0.0933472713471928, 
0.109413945850029, 0.0901760485538073, 0.109136014040399), col.group = c("Wave 1", 
"Wave 1", "Wave 2", "Wave 2", "Mean", "Mean")), row.names = c(NA, 
-6L), class = c("tbl_df", "tbl", "data.frame"))

My code:

plot_ors_fi = ggplot(data = ors_fi,
               aes(x = `col.x`, y = exp(`col.estimate`), group = as.factor(`col.group`))) +
  
  # Plot the point estimates
  geom_point(aes(size = 1,
                shape = 22,
                fill = as.factor(`col.group`)),
                stroke = 0.5,
                position = position_dodge(width = 0.4)) +
  
  # Plot point estimates text
  geom_text(aes(y = exp(`col.estimate`+1.96*`col.stderr`),
                label = format(round(exp(`col.estimate`), 2), nsmall = 2)),
            vjust = -0.8,
            size  = 3,
            position = position_dodge(width = 0.4)) +
  
  # Set the scale for the size of boxes
  scale_radius(guide  = "none",
               limits = c(0, NA_real_),
               range  = c(0, 3)) +
  
  # Plot the CIs
  geom_linerange(aes(ymin = exp(`col.estimate`-1.96*`col.stderr`),
                     ymax = exp(`col.estimate`+1.96*`col.stderr`),
                     colour = "black"), 
                 lwd = 0.5,
                 position = position_dodge(width = 0.4)) +
  
  # Use identity for aesthetic scales
  scale_shape_identity() +
  scale_colour_identity() +
  
  # Set the scale for fill colours
  scale_fill_grey(start = 0, 
                  end = 1, 
                  limits=c("Wave 1", "Wave 2", "Mean"),
                  guide="legend", 
                  position = "bottom", ## NOT WORKING?
                  name=NULL) +
  
  # Set the y-axis scale
  scale_y_continuous(trans = "log", breaks = c(1, 2, 4, 8)) +
  
  # Set the x-axis scale
  scale_x_discrete(limits = c("Pre-frail", "Frail")) +
  
  # Add titles
  xlab("Frailty Index") +
  ylab("OR (95% CI)") +
  ggtitle("")

This produces: enter image description here

As you can see the legend at present is not very useful. I couldn't find a similar question in SO where the legend fill colour does not show at all?

I'd appreciate some advice and thanks in advance.

1
rggplot2

1 Answers

0
votes

Shape needs to come out of the aes tag:

ggplot(data = ors_fi,
       aes(x = `col.x`, y = exp(`col.estimate`), group = as.factor(`col.group`))) +
  
  # Plot the point estimates
  geom_point(aes(size = 1,
                 fill = as.factor(`col.group`)),
             shape = 22,
             stroke = 0.5,
             position = position_dodge(width = 0.4))

# etc.

And legend position can be set by theme:

  # Add titles
  xlab("Frailty Index") +
  ylab("OR (95% CI)") +
  ggtitle("") +
  theme(legend.position = "bottom")

Which is hopefully what you're looking for?

enter image description here