Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
1.4k views
in Technique[技术] by (71.8m points)

dataframe - How do I refer to a data frame element with strings in R?

n <- 1
sn <- "n"
get (sn)

This will work. However, the following won't work:

n <- as.data.frame(matrix(1,2,2))
sn <- "n$V1"
get (sn)

How should I make this work?

eval(parse(text=sn))

works. Thanks.

I am doing that because there are 1000 variables in the dataframe and I need a variable passed from a function to tell which variable out of the 1000 variables that I need to work further on.

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Answer

0 votes
by (71.8m points)

You almost certainly want to pass just the name of the column within the data frame, then use [[-indexing to retrieve the vector you want:

n <- as.data.frame(matrix(1,2,2))
sn <- "V1"
n[[sn]]
## [1] 1 1

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome to OStack Knowledge Sharing Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

2.1m questions

2.1m answers

60 comments

57.0k users

...