[R] Help sought with 1. converting factor to numeric; 2. creating new dataframe

[Michael Dewey]

Comments in line

On 16/12/2014 11:25, Aditya Singh via R-help wrote:
> Dear R-experts,
>
> I am relatively new to R. Please help me in converting a dataframe into a numeric and then creating a new dataframe.
>
> R-code attached:
>
> my_xtrain=read.table("./train/X_train.txt")
> my_xtest=read.table("./test/X_test.txt")
> my_merge_data=merge(my_xtrain,my_xtest,all=TRUE)

Without knowing what is in x_train.txt and x_test.txt it is hard to be 
sure but you might be able to avoid the conversion to factors (assuming 
that is what happened by using stringsAsFactors = FALSE or as.is or 
setting colClasses.

?read.table may help here.

>
>
> ### my_merge_datad is a new dataframe in which I want my_merge_data to be numeric
> my_merge_datad=as.numeric(as.character(my_merge_data),na.rm=TRUE)
>
>
Probably unnecessary to intialise here.

> ### my_m: I want to initialize a dataframe here
> my_m=dat()
>
>

The loop is probably avoidable. Why not use apply on the columns?

mymean <- apply(my_merg_data, 2, mean)
and simlarly for the standard deviation
and then
my_m <- cbind(mymean, mysd)

Of course without the data I have not tested any of this and I may have 
misunderstood the problem but there may be enough hints here to get you 
started.

> for (i in 1: 561) {
>
> ## here in my_m[1,i] I want to store the mean of all the columns, 1 to 561
>        my_m[1,i]= mean(my_merge_data[,i])
>
> ## here in my_m[2,i] that is the second row of the new dataframe my_m I want to store the standard deviation of columns 1 to ##561
>        my_m[2,i]=std(my_merge_data[,i])
> }
>
> Thanking you,
> Aditya
>
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-- 
Michael
http://www.dewey.myzen.co.uk