如何重新排序列在qplot（R）

Question

我創建一個使用這個腳本的有色網：

require(reshape2) 
require(ggplot2) 
sum<-c(0.58,0.65,0.58,0.53,0.41,0.37) 
len<-c(0.24,0.36,0.24,0.21,0.07,0.12) 
mean<-c(0.83,0.81,0.83,0.83,0.80,0.75) 
cl2<-c(0.73,0.75,0.73,0.62,0.60,0.54) 
X<-c("het1","het3","het5","het7","het10","het15") 
df<-data.frame(X,sum,len,mean,cl2) 
a<-melt(df) 
names(a)<-c("het","variables","Correlation") 
qplot(variables, het, fill=Correlation, data=a,geom='tile') 

產生本圖：

正如你在圖中看到，y軸的行沒有正確排序。我需要對此進行排序，以正確順序獲得het1,het3,het5,het7,het10和het15。我怎樣才能做到這一點？

Answer 1

只是relevel因素創建情節之前：

require(reshape2) 
require(ggplot2) 
sum<-c(0.58,0.65,0.58,0.53,0.41,0.37) 
len<-c(0.24,0.36,0.24,0.21,0.07,0.12) 
mean<-c(0.83,0.81,0.83,0.83,0.80,0.75) 
cl2<-c(0.73,0.75,0.73,0.62,0.60,0.54) 
X<-c("het1","het3","het5","het7","het10","het15") 
df<-data.frame(X,sum,len,mean,cl2) 
a<-melt(df) 

names(a)<-c("het","variables","Correlation") 
a$het = factor(a$het, levels = X) 
qplot(variables, het, fill=Correlation, data=a,geom='tile')