Para un marco de datos de muestra:

df1 <- structure(list(country.name = structure(c(4L, 11L, 10L, 2L, 1L, 
       3L, 8L, 5L, 7L, 9L, 6L), .Label = c("Austria", "Belgium", "Czech Republic", 
       "Denmark", "France", "Germany", "Netherlands", "Norway", "Poland", 
       "Sweden", "Switzerland"), class = "factor"), level = c(2L, 2L, 
       2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L), no.regions = c(5L, 7L, 8L, 
       11L, 9L, 8L, 7L, 16L, 12L, 15L, 14L), min_result = c(42.59, 33.57, 
       43.1, 38.46, 41.76, 44.05, 41.67, 36.32, 36.18, 42.79, 39.91), 
       max_result = c(50.24, 46.56, 58.24, 57.41, 61.07, 64.56, 
       63.25, 58.19, 59.14, 69.19, 67.11), diff = c(7.65, 12.99, 
       15.14, 18.95, 19.31, 20.51, 21.58, 21.87, 22.96, 26.4, 27.2
       ), RD = c(-0.07, 0.131, -0.091, -0.153, -0.172, 0.203, -0.166, 
       0.145, -0.228, -0.266, -0.261), RDCI_lower = c(-0.21, -0.028, -0.194, -0.328, -0.376, 0.076, -0.315, 0.075, -0.407, -0.348, 
       -0.347), RDCI_upper = c(0.07, 0.29, 0.012, 0.021, 0.031, 
      0.331, -0.017, 0.216, -0.049, -0.184, -0.175), RDpvalue = c(0.3237, 
      0.1113, 0.08, 0.0829, 0.1017, 0.0023, 0.0299, 0, 0.0149, 
      0, 0), diff_order = structure(1:11, .Label = c("Denmark", 
       "Switzerland", "Sweden", "Belgium", "Austria", "Czech Republic", 
      "Norway", "France", "Netherlands", "Poland", "Germany"), class = "factor", scores = structure(c(19.31, 
      18.95, 20.51, 7.65, 21.87, 27.2, 22.96, 21.58, 26.4, 15.14, 
      12.99), .Dim = 11L, .Dimnames = list(c("Austria", "Belgium", 
      "Czech Republic", "Denmark", "France", "Germany", "Netherlands", 
      "Norway", "Poland", "Sweden", "Switzerland"))))), .Names = c("country.name", 
      "level", "no.regions", "min_result", "max_result", "diff", "RD", 
      "RDCI_lower", "RDCI_upper", "RDpvalue", "diff_order"), row.names = c(NA, 
      -11L), class = "data.frame")

Estoy tratando de crear un diagrama usando ggplot2:

library(ggplot2)

df1$diff_order <- reorder(df1$country.name, df1$diff) #Set order of countries by diff (if they are not already), and then set this to be plot 

a <- ggplot(df1, aes((x=diff_order), y=country.name,fill=level)) +
  geom_bar(stat="identity") +
  xlab("Country") +
  theme_classic() +
  coord_flip() +
  scale_fill_manual(values=c("#009E73", "#0072B2"),name="NUTS level") +
  ylim(0, 40) +
  ggtitle("All")  +
  theme(plot.title = element_text(hjust = 0)) +
  theme(axis.title.x = element_blank()) +
  theme(axis.text=element_text(size=6),
        axis.title=element_text(size=10,face="bold"))

a

Sin embargo, me sale el error:

Error: Discrete value supplied to continuous scale

Sé que este error ha sido ampliamente reportadoen otra parteSin embargo, no puedo encontrar una solución adecuada a mi problema. Según tengo entendido, R está teniendo problemas con una de mis escalas, sin embargo, puedo intentar cambiar su clase (por ejemplo, df1 $ country.name <- as.character (df1 $ country.name) df1 $ level <- as.factor (df1 $ level)), y sigo teniendo el mismo error.

¿Alguien tiene alguna idea?

Actualizar

Si cambio el código como @MLavoie sugirió ...

a <- ggplot(df1, aes((x=diff_order), y=country.name,fill=as.factor(level))) +
  geom_bar(stat="identity") +
  xlab("Country") +
  theme_classic() +
  coord_flip() +
  scale_fill_manual(values=c("#009E73", "#0072B2"),name="NUTS level") +
  ggtitle("All")  +
  theme(plot.title = element_text(hjust = 0)) +
  theme(axis.title.x = element_blank()) +
  theme(axis.text=element_text(size=6),
        axis.title=element_text(size=10,face="bold"))

... Obtuve el siguiente error:

Error in geom_bar(stat = "identity") + xlab("Country") : 
  non-numeric argument to binary operator

¿Qué estoy haciendo mal?

Puedo producir este gráfico hasta ahora, pero quiero los países (en orden) solo en los ejes y y 'diff' en el eje x. ¿Algunas ideas?