Merge 2 columns into one in dataframe [closed]

问题

Closed. This question needs debugging details. It is not currently accepting answers.

---

Want to improve this question? Update the question so it's on-topic for Stack Overflow.

Closed 6 years ago.

Improve this question

This should be simple, but I am struggling with it.

I want to combine two columns in a single dataframe into one. I have separate columns for custemer ID (20227) and year (2009). I want to create a new column that has both (2009_20227).

回答1:

Some alternative way with function unite in tidyr:

library(tidyr)
df = data.frame(year=2009:2013, customerID=20227:20231) # using akrun's data

unite(df, newcol, c(year, customerID), remove=FALSE)

#      newcol year customerID
#1 2009_20227 2009      20227
#2 2010_20228 2010      20228
#3 2011_20229 2011      20229
#4 2012_20230 2012      20230
#5 2013_20231 2013      20231

回答2:

You could use paste

transform(dat, newcol=paste(year, customerID, sep="_"))

Or use interaction

dat$newcol <- as.character(interaction(dat,sep="_"))

data

dat <- data.frame(year=2009:2013, customerID=20227:20231)

回答3:

Another alternative (using the example of @akrun):

dat <- data.frame(year=2009:2013, customerID=20227:20231)
dat$newcol <- paste(dat$year, dat$customerID, sep="_")

来源：https://stackoverflow.com/questions/27906021/merge-2-columns-into-one-in-dataframe