[R] how to do inverse log of every value in every column in data frame

[Rui Barradas]

Hello,

The answer is given but there is no need to coerce to matrix first, as 
long as the columns are numeric.
 From ?exp, right at the beginning of section Details:

Details
All except logb are generic functions: methods can be defined for them 
individually or via the Math group generic.


Follow the link Math:


Details
There are four groups for which S3 methods can be written, namely the 
"Math", "Ops", "Summary" and "Complex" groups. These are not R objects 
in base R, but methods can be supplied for them and base R contains 
factor, data.frame and difftime methods for the first three groups.


And exp is the group "Math", 2nd bullet.

class(mtcars)
#[1] "data.frame"
exp(mtcars)
# output omitted


But if a column is not numeric the method Math.data.frame throws an error.


exp(iris)
#Error in Math.data.frame(iris) :
#  non-numeric-alike variable(s) in data frame: Species

exp(iris[-5])     # remove the offending column
# output omitted


Hope this helps,

Rui Barradas


Às 18:23 de 14/10/21, Ana Marija escreveu:
> Thank you so much!
> 
> On Thu, Oct 14, 2021 at 12:17 PM Bert Gunter <bgunter.4567 using gmail.com> wrote:
> 
>> As all of your columns are numeric, you should probably convert your df to
>> a matrix. Then use exp() on that, of course:
>> exp(as.matrix(b))
>>
>> see ?exp
>>
>> Bert Gunter
>>
>> "The trouble with having an open mind is that people keep coming along and
>> sticking things into it."
>> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
>>
>>
>> On Thu, Oct 14, 2021 at 10:10 AM Ana Marija <sokovic.anamarija using gmail.com>
>> wrote:
>>
>>> Hi All,
>>>
>>> I have a data frame like this:
>>>
>>>> head(b)
>>>       LRET02    LRET04    LRET06    LRET08    LRET10    LRET12    LRET14
>>> 1         0 0.6931472         . 1.0986123 1.0986123 1.0986123 0.6931472
>>> 2 2.1972246 2.4849066 2.4849066         . 2.5649494 2.6390573 2.6390573
>>> 3 1.6094379 1.7917595 1.6094379 1.7917595 2.0794415 1.9459101 2.0794415
>>> 4         0         0         0         0         0         0         0
>>> 5 0.6931472         0 1.0986123 1.0986123 0.6931472 0.6931472 0.6931472
>>> 6 1.0986123 1.0986123 1.0986123 0.6931472 1.0986123 1.3862944 1.0986123
>>>
>>> All values in this data frame are product of natural log. I have to do
>>> inverse of it.
>>> So for example do do inverse of 0.6931472 I would do:
>>>> 2.718281828^0.6931472
>>> [1] 2
>>>
>>> How do I perform this operation for every single value in this data frame?
>>>
>>> The original data frame is this dimension:
>>>> dim(b)
>>> [1] 1441   18
>>>
>>> Thanks
>>> Ana
>>>
>>>          [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> https://stat.ethz.ch/mailman/listinfo/r-help
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>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>