如何将点添加到堆积的条形图中

Question

I would like to add points (the variable nb species) on my already existing chart. I tried to add the points with the function geom_point but unfortunately i have this error:

"Discrete value supplied to continuous scale".

You will find below my data and my code.

  structure(list(SOUNAME = c("BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)", 
"BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)", 
"BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)", 
"BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)", 
"BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)", 
"BALLYSHANNON (CATHLEENS FALL)", "BALLYSHANNON (CATHLEENS FALL)"
), year_month = c("2014-05", "2014-05", "2014-05", "2014-05", 
"2014-06", "2014-06", "2014-06", "2014-06", "2014-07", "2014-07", 
"2014-07", "2014-07"), pre_type = c("NONE", "HEAVY", "LIGHT", 
"MEDIUM", "NONE", "HEAVY", "LIGHT", "MEDIUM", "NONE", "HEAVY", 
"LIGHT", "MEDIUM"), pre_value = c(3, 6, 20, 2, 16, 2, 9, 2, 3, 
3, 22, 3), tem_type = c("V_COLD", "COLD", "HOT", "MEDIUM", "V_COLD", 
"COLD", "HOT", "MEDIUM", "V_COLD", "COLD", "HOT", "MEDIUM"), 
    tem_value = c(0, 31, 0, 0, 0, 24, 6, 0, 0, 23, 8, 0), nb_species = c("NA", 
    "3", "NA", "NA", "NA", "NA", "NA", "NA", "NA", "NA", "NA", 
    "NA"), x = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 
    3L)), .Names = c("SOUNAME", "year_month", "pre_type", "pre_value", 
"tem_type", "tem_value", "nb_species", "x"), row.names = c(NA, 
-12L), class = c("tbl_df", "tbl", "data.frame"))

ggplot(data = complet_b, aes(x = x, y = pre_value, fill = pre_type), stat = "identity") +
          scale_x_continuous(breaks=1:3, labels=unique(complet_b$year_month)) +
          geom_bar(stat = "identity", width=0.3) +
          xlab("date") + ylab ("Number of days of precipitation") +
          ggtitle("Precipitation per month") + labs(fill = "Frequency") +
          geom_bar(data=complet_b,aes(x=x+0.4, y=tem_value, fill=tem_type), width=0.3, stat = "identity") +
          xlab("date") + ylab("Number of days of temperature") +
          ggtitle("Temperature per month") + labs(fill = "Frequency") 

Thanks a lot for take time to help me !!

Answer 1

Your column nb_species is in character format, convert it to numeric and you are good to go.

A quick str(complet_b) would tell you that your column format.

complet_b$nb_species <- as.numeric(complet_b$nb_species)

Here is your code and plot with the dot present in the graph:

library(ggplot2)
ggplot(data = complet_b, aes(x = x, y = pre_value, fill = pre_type), stat = "identity") +
  scale_x_continuous(breaks=1:3, labels=unique(complet_b$year_month)) +
  geom_bar(stat = "identity", width=0.3) +
  xlab("date") + ylab ("Number of days of precipitation") +
  ggtitle("Precipitation per month") + labs(fill = "Frequency") +
  geom_bar(data=complet_b,aes(x=x+0.4, y=tem_value, fill=tem_type), width=0.3, stat = "identity") +
  xlab("date") + ylab("Number of days of temperature") +
  geom_point(aes(x = x, y= nb_species)) +
  ggtitle("Temperature per month") + labs(fill = "Frequency")