[R] How to exclude a column by name?

[Peter Dalgaard]

Paul Hiemstra wrote:
> Zeljko Vrba wrote:
>> Given an arbitrary data frame, it is easy to exclude a column given
>> its index:
>> df[,-2].  How to do the same thing given the column name?  A naive
>> attempt
>> df[,-"name"] did not work :)
>>
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>> and provide commented, minimal, self-contained, reproducible code.
>>   
> Hi,
> 
> This piece of code does the trick. Most important is the which() command:
> 
> df = data.frame(a = runif(10), b = runif(10))
> df[,-which(names(df) == "a")]
> 

You don't actually need which() (and the approach runs into problems if
"a" isn't there). Just select the others:

df[, names(df) != "a"]

Or, BTW, you can use within()

aq <- within(airquality, rm(Day))

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