[R] Question about Rfast colMins and colMaxs

[Stephen H. Dawson, DSL]

Thanks, Bill.

How do you go about getting maximum and minimum values from your 
columns? Do you simply do them one column at a time? The functions I am 
identifying from Rfast do this work in bulk.


*Stephen Dawson, DSL*
/Executive Strategy Consultant/
Business & Technology
+1 (865) 804-3454
http://www.shdawson.com <http://www.shdawson.com>


On 11/30/21 3:24 PM, Bill Dunlap wrote:
> You can use as.matrix() to convert your data.frame to a matrix, but 
> that loses the speed/space advantages of colMins (as well as causing 
> issues if some columns are not numeric).  You could write to the 
> maintainer of the package to ask that data.frames be directly 
> supported.  In the meantime you could use
>    vapply(yourDataFrame, which.min, FUN.VALUE=NA_real_)
> or
>     vapply(yourDataFrame, min, FUN.VALUE=NA_real_)
> instead of colMins.
>
> -Bill
>
> On Tue, Nov 30, 2021 at 10:55 AM Stephen H. Dawson, DSL via R-help 
> <r-help using r-project.org <mailto:r-help using r-project.org>> wrote:
>
>     Hi,
>
>
>     I am working to understand the Rfast functions of colMins and
>     colMaxs. I
>     worked through the example listed on page 54 of the PDF.
>
>     https://cran.r-project.org/web/packages/Rfast/index.html
>     <https://cran.r-project.org/web/packages/Rfast/index.html>
>
>     https://cran.r-project.org/web/packages/Rfast/Rfast.pdf
>     <https://cran.r-project.org/web/packages/Rfast/Rfast.pdf>
>
>     My data is in a CSV file. So, I bring it into R Studio using:
>     Data <- read.csv("./input/DataSet05.csv", header=T)
>
>     However, I read the instructions listed on page 54 of the PDF
>     saying I
>     need to bring data into R using a matrix. I think read.csv brings the
>     data in as a dataframe. I think colMins is failing because it is
>     looking
>     for a matrix but finds a dataframe.
>
>      > colMaxs(Data)
>     Error in colMaxs(Data) :
>        Not compatible with requested type: [type=list; target=double].
>      > colMins(Data, na.rm = TRUE)
>     Error in colMins(Data, na.rm = TRUE) :
>        unused argument (na.rm = TRUE)
>      > colMins(Data, value = FALSE, parallel = FALSE)
>     Error in colMins(Data, value = FALSE, parallel = FALSE) :
>        Not compatible with requested type: [type=list; target=double].
>
>     QUESTION
>     What is the best practice to bring a csv file into R Studio so it
>     can be
>     accessed by colMaxs and colMins, please?
>
>
>     Thanks,
>     -- 
>     *Stephen Dawson, DSL*
>     /Executive Strategy Consultant/
>     Business & Technology
>     +1 (865) 804-3454
>     http://www.shdawson.com <http://www.shdawson.com>
>     <http://www.shdawson.com <http://www.shdawson.com>>
>
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