Selecting columns in R data frame based on those *not* in a vector
I'm familiar with being able to extract columns from an R data frame (or matrix) like so:
df.2 <- df[, c("name1", "name2", "name3")]
But can one use a ! or other tool to select all but those listed columns?
For background, I have a data frame with quite a few column vectors and I'd like to avoid:
- Typing out the majority of the names when I could just remove a minority
- Using the much shorter
df.2 <- df[, c(1,3,5)]because when my .csv file changes, my code goes to heck since the numbering isn't the same anymore. I'm new to R and think I've learned the hard way not to use number vectors for larger df's that might change.
I tried:
df.2 <- df[, !c("name1", "name2", "name3")]
df.2 <- df[, !=c("name1", "name2", "name3")]
And just as I was typing this, found out that this works:
df.2 <- df[, !names(df) %in% c("name1", "name2", "name3")]
Is there a better way than this last one?
Answer
An alternative to grep is which:
df.2 <- df[, -which(names(df) %in% c("name1", "name2", "name3"))]