Question

I am a complete newbie with R and I ask for your help.

I have a data frame DF like this:

user      age    email        address   ...
user1     20     u1@domain    address1  ...
user2     19     u2@domain    address2  ...
user3     30     u3@domain    address3  ...
...
userm     32     um@domain    addressm ...
...
usern     xx     un@domain    address4  ...

I have a vector as following:

user1
user3
...
userm

I need to have the following:

user      age    email        address   newcol ...
user1     20     u1@domain    address1  yes    ...
user2     19     u2@domain    address2  no     ...
user3     30     u3@domain    address3  yes    ...
...
userm     32     um@domain    addressm  yes    ...
...
usern     xx     un@domain    address4  no     ...

In short, add a new column to DF containing no (as default) and yes if the correspondent user is in the vector.

Any advise is appreciated,
Thanks for your time.

Answer 1

To expand on Joran’s answer:

Assuming your data.frame is named df. Make a new column in your data.frame called newcol:

df$newcol <- 'no'

Then change the values in newcol to ‘yes’ if they’re %in% your vector (I’m assuming its named vec).

df$newcol[df$user %in% vec] <- 'yes'

You could also do this in one step using ifelse:

df$newcol <- ifelse(df$user %in% vec, 'yes', 'no')

Or if you wanted to get tricky you could use merge(..., all=TRUE)…