使用geom_bar在ggplot2中未显示的图

Question

I am trying to plot stacked bars using ggplot() and geom_bar()

Sample data (Titanic Kaggle question):

PassengerId   Survived   Age
          1          0    25
          2          1    20
          3          1    40
          4          0    10

I am trying to show stacked bars of survival and death for each age range (I have divided age into bins). Plot is not visible when I execute the command. and when I add print() function, I get the error as

Error: No layers in plot

Please tell if there is anything I am missing out here ?

breaks <- seq(min(train$Age), max(train$Age), 10)
p <- ggplot(train, aes(x=train$Age, y=length(train$PassengerId)), xlab = "age", ylab = "count", main = "survival", 
   fill = Survived + geom_bar(stat = "identity", bin = breaks))

print(p)

"train" is object in which I stored the data.

Answer 1

There are a few issues here:

First you should remove the rows where age is NA, otherwise you can't create a sequence.

train<-train[!is.na(train$Age),]

Then you should change your y value to train$Survived (why did you use length(train$PassengerId) ? - it doesn't display anything) The thing that @Pascal mentioned is also correct: You have to put + geom_bar(stat="identity", bin=breaks) outside. and you need to add the axes and title differently in ggplot.

This is the complete working code:

train<-train[!is.na(train$Age),]

breaks <- seq(min(train$Age), max(train$Age), 10)
p <- ggplot(train, aes(x=train$Age, y=train$Survived), 
            fill = Survived)+ geom_bar(stat="identity", bin=breaks)
p <- p+labs(x="age", y="count")

p <- p+theme(plot.title= element_text("survival"))


print(p)

Results in this graph:

Answer 2

apart from Pascal's hint, you may want to:

• Use factors for colored column (Survived)
• Use different geom_bar() and aes() params as suggested

Code:

train <- data.frame(PassengerId = 1:4, Survived = factor(c(0,1,1,0)), Age = c(25, 20, 40, 10))
BIN.WIDTH <- 10
my.breaks <- seq(from = min(train$Age), to = max(train$Age) + BIN.WIDTH, by = BIN.WIDTH)
ggplot(train, aes(Age, fill = Survived)) + geom_bar(breaks = my.breaks)

Plot: