[英]Expand data.frame by adding new column
Here an example of my data.frame(s): 这是我的data.frame(s)的示例:
df = data.frame(x=c(1871:1872))
df2 = data.frame(y=c(1:3))
How can I expand df
with df2
observations? 如何使用
df2
观测值扩展df
?
Desired output: 所需的输出:
x y
1871 1
1871 2
1871 3
1872 1
1872 2
1872 3
I couldn't find any solution yet. 我找不到任何解决方案。 Thanks
谢谢
A solution using expand.grid
that gives you all combinations of two variables. 使用
expand.grid
的解决方案可为您提供两个变量的所有组合。
df = data.frame(x=c(1871:1872))
df2 = data.frame(y=c(1:3))
expand.grid(x = df$x, y = df2$y)
# x y
# 1 1871 1
# 2 1872 1
# 3 1871 2
# 4 1872 2
# 5 1871 3
# 6 1872 3
One way with lapply
: lapply
一种方法:
do.call(rbind, lapply(df$x, function(z) {
cbind(z, df2)
}))
# z y
#1 1871 1
#2 1871 2
#3 1871 3
#4 1872 1
#5 1872 2
#6 1872 3
lapply
iterates over df$x
and cbind
s the whole df2
to each element of df$x
. lapply
在df$x
迭代,并将整个df2
cbind
到df$x
每个元素。 do.call
combines everything together in one data.frame. do.call
将所有内容组合到一个data.frame中。
A third (but less elegant) solution: 第三种(但不太优雅)的解决方案:
data.frame(x=rep(df$x, each=nrow(df2)),
y=rep(df2$y,length(unique(df$x)))
)
# x y
# 1 1871 1
# 2 1871 2
# 3 1871 3
# 4 1872 1
# 5 1872 2
# 6 1872 3
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.