Subset columns in R dataframe issue?

Question

I have a dataframe df that I want to subset in the following way:

Columns 1-7 and a vector of columns cols:

cols = c("rs1057079", "rs1057079.1", "rs4845882", "rs4845882.1", "rs1891932", "rs1891932.1", "rs530296", "rs530296.1", "rs10497340", "rs10497340.1")

So what I did is df[, c(1:7, cols)] but R throws an error:

Error in `[.data.frame`(df, , c(seq(1:7), SNPs_dup)) : 
  undefined columns selected

What is wrong here?? I can subset on 1:7 and cols but why not on both of them?

akuiper · Accepted Answer · 2017-12-04 16:18:38Z

1

c(1:7, cols) coerces the sequence 1:7 to characters which are further treated as columns names '1', '2' ... instead of column positions, you can extract the 1-7 column names and then concatenate with cols and subset:

df[,c(names(df)[1:7], cols)]

Or convert cols to positions:

df[,c(1:7, match(cols, names(df)))]

edited Dec 4, 2017 at 16:18

answered Dec 4, 2017 at 16:17

akuiper

216k33 gold badges362 silver badges379 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Dr. Richard Tennen Over a year ago

I see, but how to avoid c() to do this? This is the only way?

akuiper Over a year ago

You can't stop c from doing this, since it produces an atomic vector which must have the same data type. I provided an alternative way for this.

Collectives™ on Stack Overflow

Subset columns in R dataframe issue?

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related