# [R] list to dataframe conversion-testing for identical

arun smartpink111 at yahoo.com
Sun Jul 1 19:55:47 CEST 2012

```HI R help,

I was trying to get identical data frame from a list using two methods.

#Suppose my list is:
listdat1<-list(rnorm(10,20),rep(LETTERS[1:2],5),rep(1:5,2))
#Creating dataframe using cbind

dat1<-data.frame(do.call("cbind",listdat1))
colnames(dat1)<-c("Var1","Var2","Var3")
#Second dataframe conversion

dat2<-data.frame(Var1=listdat1[[1]],Var2=listdat1[[2]],Var3=listdat1[[3]])

#Structure is different in two datasets
>str(dat1)
'data.frame':    10 obs. of  3 variables:
\$ Var1: Factor w/ 10 levels "18.6153321029756",..: 5 2 6 8 7 9 1 4 3 10
\$ Var2: Factor w/ 2 levels "A","B": 1 2 1 2 1 2 1 2 1 2
\$ Var3: Factor w/ 5 levels "1","2","3","4",..: 1 2 3 4 5 1 2 3 4 5
> str(dat2)
'data.frame':    10 obs. of  3 variables:
\$ Var1: num  20.3 19.2 20.5 20.9 20.5 ...
\$ Var2: Factor w/ 2 levels "A","B": 1 2 1 2 1 2 1 2 1 2
\$ Var3: int  1 2 3 4 5 1 2 3 4 5

#Converting structure of dat1 to match da2 structure
dat1<-within(dat1,{Var1<-as.numeric(as.character(Var1))
Var3<-as.integer(Var3)})

Var1 Var2 Var3
1 20.27193    A    1
2 19.17586    B    2
3 20.53197    A    3
4 20.93615    B    4
5 20.53498    A    5
6 21.02044    B    1
Var1 Var2 Var3
1 20.27193    A    1
2 19.17586    B    2
3 20.53197    A    3
4 20.93615    B    4
5 20.53498    A    5
6 21.02044    B    1

#New structure identical(str(dat1),str(dat2))
'data.frame':    10 obs. of  3 variables:
\$ Var1: num  19.9 19 21.2 20.7 20.4 ...
\$ Var2: Factor w/ 2 levels "A","B": 1 2 1 2 1 2 1 2 1 2
\$ Var3: int  1 2 3 4 5 1 2 3 4 5
'data.frame':    10 obs. of  3 variables:
\$ Var1: num  19.9 19 21.2 20.7 20.4 ...
\$ Var2: Factor w/ 2 levels "A","B": 1 2 1 2 1 2 1 2 1 2
\$ Var3: int  1 2 3 4 5 1 2 3 4 5
[1] TRUE

#structure is identical and dataframe looks to be same, but it is not identical.
> identical(dat1,dat2)
[1] FALSE

Is it something to do with the floating point?

Thanks,

A.K.

```