小编ddu*_*801的帖子

"vs"变量在R中的"mtcars"数据集中意味着什么？帮助文件说它意味着"V/S",但这并不具有启发性.

命令:

data(mtcars)
head(mtcars)
?mtcars

我正在看Hadley Wickham的以下例子ggplot2:

library(ggplot2)
library(maps)
states<-map_data("state")
arrests<-USArrests
names(arrests)<-tolower(names(arrests))
arrests$region<-tolower(rownames(USArrests))

chloro<-merge(states, arrests, by="region")
chloro<-chloro[order(chloro$order), ]
qplot(long, lat, data=chloro, group=group, fill = assault, geom="polygon")

我想在地图上为一些着名的美国城市添加积分,但我无法做到.我试过了:

base_map<-qplot(long, lat, data=chloro, group=group, fill = assault, geom="polygon")
base_map + qplot(long, lat, data=us.cities) + borders("state", size=.5)

但是我收到以下错误:

Error in p + o : non-numeric argument to binary operator
In addition: Warning message:
Incompatible methods ("+.ggplot", "Ops.data.frame") for "+""

我该如何添加这些积分？

我有一个大的data.table,结构类似于df:

library("data.table")
df <- data.frame(part = c("A", "B", "A", "C", "A", "D", "B", "D", "E"), 
                 day = c(1, 2, 3, 4, 5, 6, 6, 7, 15), 
                 code = c("S", "S", "P", "X", "P", "S", "P", "P", "P"))
setDT(df)
df
   part day code
1:    A   1    S
2:    B   2    S
3:    A   3    P
4:    C   4    X
5:    A   5    P
6:    D   6    S
7:    B   6    P
8:    D   7    P
9:    E  15    P …