[R] how can I delete those columes with the same element in every row?

[bbslover]

it is perfect，you give me a great help. thanks R and Berend Hasselman, my
friends. but I think I do have more questions to ask. 

thank you!

Berend Hasselman wrote:
> 
> 
> 
> bbslover wrote:
>> 
>> e.g.  
>> 
>> a=
>>   a b c d e
>> 1 1 1 3 1 1
>> 2 1 2 3 4 5
>> 3 1 3 3 8 3
>> 4 1 4 3 3 5
>> 5 1 1 3 1 1        I want to delete  colume a  and colume c, because they
>> have the same values in every row, then ,I want to get this data.frame .
>> 
>> b=
>>   b d  e
>> 1 1 1  1
>> 2 2 4  5
>> 3 3 8  3
>> 4 4 3  5
>> 5 1 1  1    
>> 
> 
> Try this
> 
> xdf  <- apply(data.f, 2, function(x) x==x[1])
> data.f <- data.f[,!apply(xdf,2,all)]
> data.f
> 
> 
> 

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