r ggplot adding factor category labels to appear

Question

I am using ggplot in Rstudio to try and create a barplot showing the number of indicidents when the wind comes from a certain direction.

My data does not include wind coming from all directions (categorised as "N", "NE","E","SE","S","SW","W","NW"). As such my plots look strange, as they miss off certain wind directions.

Is there a way to add in category classes and force these to appear on the graph?

Update: Subset of my data using dput is:

structure(list(Sum.of.Incidents = c(1L, 2L, 2L, 0L, 1L, 0L, 0L, 
2L, 2L, 0L, 1L, 0L, 0L, 0L, 1L, 0L, 0L, 0L, 0L, 5L, 0L, 4L, 1L, 
1L, 0L, 0L, 0L, 0L), WindDirCompass = structure(c(2L, 2L, 7L, 
8L, 6L, 5L, 2L, 1L, 1L, 2L, 8L, 8L, 7L, 3L, 7L, 1L, 8L, 6L, 6L, 
3L, 8L, 6L, 7L, 7L, 7L, 8L, 8L, 6L), .Label = c("N", "NE", "E", 
"SE", "S", "SW", "W", "NW"), class = "factor")), row.names = c(NA, 
-28L), .Names = c("Sum.of.Incidents", "WindDirCompass"), spec = structure(list(
    cols = structure(list(Sum.of.Incidents = structure(list(), class = c("collector_integer", 
    "collector")), WindDirCompass = structure(list(), class = c("collector_character", 
    "collector"))), .Names = c("Sum.of.Incidents", "WindDirCompass"
    )), default = structure(list(), class = c("collector_guess", 
    "collector"))), .Names = c("cols", "default"), class = "col_spec"), class = c("tbl_df", 
"tbl", "data.frame"))

The current code I am running to produce the plot:

ggplot(example, aes(x = factor(WindDirCompass),
                                     y = Sum.of.Incidents)) +
     geom_bar(stat = "identity", fill = "#990033") +
     labs(title = "", x = "Wind direction", y = "Number of incidents") +
 scale_x_discrete(drop = FALSE)

I have also ordered by the directions:

example$WindDirCompass <-
     factor(example$WindDirCompass,
            c("N", "NE","E","SE","S","SW","W","NW"))

As such "SE" is missing. Is there a way to force this factor to appear. I have other instances where only one or two directions have incidents and so most wind directions are then missing.

please show some data using `dput()` and show what you have already tried. — Roman, Jan 27 '17 at 10:58
yes. (if you [add some data and code](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) someone might be able to show you how.) — erc, Jan 27 '17 at 10:59

score 1 · Accepted Answer · answered Jan 27 '17 at 12:49

I think you get your desired plot when you remove factor() from aes() and add breaks:

ggplot(example, aes(x = WindDirCompass,
                    y = Sum.of.Incidents)) +
  geom_bar(stat = "identity", fill = "#990033") +
  labs(title = "", x = "Wind direction", y = "Number of incidents") +
  scale_x_discrete(drop = FALSE, breaks = levels(example$WindDirCompass))

Using factor() had led to the unused level being removed:

> levels(example$WindDirCompass)
[1] "N"  "NE" "E"  "SE" "S"  "SW" "W"  "NW"
> levels(factor(example$WindDirCompass))
[1] "N"  "NE" "E"  "S"  "SW" "W"  "NW"

score 0 · Answer 2 · answered Jan 27 '17 at 12:09

0

If it's just that factor levels drop because they have 0 incidents, you might just need to add: + scale_x_discrete(drop=FALSE)

In your code this looks like:

ggplot(transect_weather_summary, aes(x = factor(WindDirCompass),
                                 y = Sum.of.Incidents)) +
    geom_bar(stat = "identity", fill = "#990033") +
    labs(title = "", x = "Wind direction", y = "Number of incidents")+
    scale_x_discrete(drop=FALSE)

If this is not the problem you should give some data examples

answered Jan 27 '17 at 12:09

Gregor Ma

26
1
4

thanks. But when I tried this it does not work as there is no entries for these directions at all. I realise I can force this by adding in these as blank rows, but hoped there was a neater way to do this rather than making up data. – cjp Jan 27 '17 at 12:27

r ggplot adding factor category labels to appear

2 Answers2