Tidyeval and if-statement in ggplot wrapper

[Trick]

I am trying to make a ggplot2 wrapper that adjusts the scale on the y-axis depending on the scale of y.

• plot_1: gives an error
• plot_2: with tidyeval, but the output has no
  values on the y-axis
• plot_3: this is how it should look

Any idea what causes this problem?
Maybe there is a different approach to this problem?

I hope the example helps to understand my problem. Thanks in advance!

# setup -------------------------------------------------------------------

library(ggplot2)

df <- data.frame(
  childs = c(3, 0, 2, 4, 2, 2, 2, 3, 3, 4, 5, 4, 3, 5, 7, 2, 6, 5, 0, 2),
  agegrp = as.factor(c("Age 45-55",
                       "Age 55-65","Age 65+","Age 35-45","Age 45-55","Age 45-55",
                       "Age 45-55","Age 18-35","Age 35-45","Age 65+",
                       "Age 18-35","Age 65+","Age 18-35","Age 55-65",
                       "Age 65+","Age 18-35","Age 55-65","Age 55-65",
                       "Age 18-35","Age 35-45")),
  religion = as.factor(c("None","None",
                         "Catholic","Catholic","None","None","None","Catholic",
                         "Protestant","None","Protestant","Protestant",
                         "Catholic","Protestant","Catholic","Other",
                         "Protestant","Protestant","None","Protestant"))
)

# function ----------------------------------------------------------------

plot_1 <- function(data, x, y, fill) {
  
  plot <-
    ggplot(data = data,
           mapping = aes(x = {{ x }}, y = {{ y }}, fill = {{ fill }})) +
    geom_col(position = "dodge")

  if (is.numeric(y)) {
    scale <-
      scale_y_continuous(expand = expansion(mult = c(0, 0.05)),
                         breaks = scales::breaks_extended(),
                         labels = scales::label_number(big.mark = "'"))
  } else {
    scale <-
      scale_y_discrete(expand = expansion(mult = c(0, 0.05)),
                       breaks = scales::breaks_extended(),
                       labels = scales::label_number(big.mark = "'"))
  }

  plot +
    scale +
    cowplot::theme_minimal_hgrid()
}

plot_2 <- function(data, x, y, fill) {
  
  plot <-
    ggplot(data = data,
           mapping = aes(x = {{ x }}, y = {{ y }}, fill = {{ fill }})) +
    geom_col(position = "dodge")
  
  cond <- enquo(y) # tidyeval
  
  if (is.numeric(cond)) {
    scale <-
      scale_y_continuous(expand = expansion(mult = c(0, 0.05)),
                         breaks = scales::breaks_extended(),
                         labels = scales::label_number(big.mark = "'"))
  } else {
    scale <-
      scale_y_discrete(expand = expansion(mult = c(0, 0.05)),
                       breaks = scales::breaks_extended(),
                       labels = scales::label_number(big.mark = "'"))
  }
  
  plot +
    scale +
    cowplot::theme_minimal_hgrid()
}

plot_3 <- function(data, x, y, fill) {
  
  plot <-
    ggplot(data = data,
           mapping = aes(x = {{ x }}, y = {{ y }}, fill = {{ fill }})) +
    geom_col(position = "dodge")

  plot +
    cowplot::theme_minimal_hgrid()
}

# test --------------------------------------------------------------------

plot_1(df, agegrp, childs, religion)
#> Error in plot_1(df, agegrp, childs, religion): object 'childs' not found
plot_2(df, agegrp, childs, religion)

plot_3(df, agegrp, childs, religion)

^{Created on 2022-10-14 by the reprex package (v2.0.1)}

[scottyd22]

After making the following updates to plot_2(), I believe it now produces the desired outcome.

• cond <- pull(data, {{y}}) - This update pulls the desired column from data, which can then be tested for numeric. Before, this check was not coming back as TRUE for childs and was always moving to the discrete option.
• scale_y_discrete(expand = expansion(mult = c(0, 0.05))) - The breaks and labels arguments were removed because based on the data, extending the breaks and setting a number label are not necessary actions for factors (each break will be a factor, no more are needed).

Here is the code and associated outcomes for various input options:

# function ----------------------------------------------------------------
plot_2 <- function(data, x, y, fill) {
  
  plot <-
    ggplot(data = data,
           mapping = aes(x = {{ x }}, y = {{ y }}, fill = {{ fill }})) +
    geom_col(position = "dodge")
  
  cond <- pull(data, {{y}}) # tidyeval
  
  if (is.numeric(cond)) {
    scale <-
      scale_y_continuous(expand = expansion(mult = c(0, 0.05)),
                         breaks = scales::breaks_extended(),
                         labels = scales::label_number(big.mark = "'"))
  } else {
    scale <-
      scale_y_discrete(expand = expansion(mult = c(0, 0.05)))
  }
  
  plot +
    scale +
    cowplot::theme_minimal_hgrid()
}


# test --------------------------------------------------------------------
plot_2(df, agegrp, childs, religion)

plot_2(df, childs, agegrp, religion)

plot_2(df, religion, agegrp, childs)

Created on 2022-10-14 with reprex v2.0.2.9000

[Trick]

That's great! Thank you for your helpful explanation.

It works perfect for me. The way I see it, with {{ }} you can follow the same Syntax with ggplot2 & dyplr in functions as in interactive sessions?

Here is another post with further information on this topic.
Referencing variables in functions using {{}}