How to subset a Data frame column wise using column names?

Question

I have created a data frame named z.

  a = c(1,1,1);
  b = c(2,2,2);
  c = c(3,3,3);
  d = c(4,4,4);
  z = data.frame(a,b,c,d);

I want to remove column c and d from data frame z.

I tried this code

p = subset(z , colnames(z) == c('a' , 'b'))

But i am getting this result

a   b   c   d
1   2   3   4   
1   2   3   4

What changes should i make in this command to remove column c and d from z.

Or argument `select`: `subset(z, select = c('a' , 'b'))`. BTW, why the semi-colon at the end of instructions? `R` is not the C language, the semi-colon separates instructions so when youend an instruction line with it, you are in fact separating it from the end, the NULL instruction. — Rui Barradas, Aug 23 '17 at 17:55

www · Answer 1 · 2020-07-21T13:47:31.767

20

We can use the following to specify which columns to select by names.

z[, c("a", "b")]

This also works.

z[c("a", "b")]

Or we can use the following to first specify which columns to remove in a vector, and then select the columns not in that vector.

cols_remove <- c("c", "d")
z[, !(colnames(z) %in% cols_remove)]

edited Jul 21 '20 at 13:47

answered Aug 23 '17 at 17:53

www

keeps <- c("a, "b") DF[keeps] – Sateesh Jul 16 '20 at 06:11
@Sateesh Your comment is unclear. It is not reproducible. What do you want to achieve? – www Jul 16 '20 at 06:24
@Sateesh Is this R code? – www Jul 16 '20 at 06:54
@Sateesh You have not responded my question. What is the purpose of your comment? Is your code really working in R? – www Jul 17 '20 at 13:10
yes it works... – Sateesh Jul 21 '20 at 12:47
keeps <- c("a, "b") – Sateesh Jul 21 '20 at 12:47
df <- df[keeps] – Sateesh Jul 21 '20 at 12:47
@Sateesh Thanks for your response. Now I see that you did not properly format your previous comment, and you did not use the same data frame name as the OP. – www Jul 21 '20 at 13:47
@Sateesh I have updated my post based on your comment. – www Jul 21 '20 at 13:47

1 Answers1