[R] Converting "list of data frame" to data frame

[jim holtman]

since you didn't supply a reproducible example, here is a test that I
ran with varying number of rows that seems to work fine.  You might
want to provide at leat an "str" of the structure that you are doing
the rbind on.


> x <- lapply(1:10, function(z){
+     data.frame(a=runif(z), b=rnorm(z), c=factor(seq(z)))
+ })
> str(x)
List of 10
 $ :'data.frame':       1 obs. of  3 variables:
  ..$ a: num 0.986
  ..$ b: num -0.543
  ..$ c: Factor w/ 1 level "1": 1
 $ :'data.frame':       2 obs. of  3 variables:
  ..$ a: num [1:2] 0.8121 0.0772
  ..$ b: num [1:2] -0.349 -1.008
  ..$ c: Factor w/ 2 levels "1","2": 1 2
 $ :'data.frame':       3 obs. of  3 variables:
  ..$ a: num [1:3] 0.970 0.989 0.176
  ..$ b: num [1:3]  0.1058  0.4570 -0.0772
  ..$ c: Factor w/ 3 levels "1","2","3": 1 2 3
 $ :'data.frame':       4 obs. of  3 variables:
  ..$ a: num [1:4] 0.3692 0.7254 0.4861 0.0638
  ..$ b: num [1:4] 0.788 2.075 1.027 1.208
  ..$ c: Factor w/ 4 levels "1","2","3","4": 1 2 3 4
 $ :'data.frame':       5 obs. of  3 variables:
  ..$ a: num [1:5] 0.109 0.333 0.837 0.277 0.587
  ..$ b: num [1:5]  0.9811  0.5324 -0.0905  0.1565 -0.7373
  ..$ c: Factor w/ 5 levels "1","2","3","4",..: 1 2 3 4 5
 $ :'data.frame':       6 obs. of  3 variables:
  ..$ a: num [1:6] 0.420 0.334 0.865 0.177 0.493 ...
  ..$ b: num [1:6]  0.162  2.025 -0.704  0.961  1.790 ...
  ..$ c: Factor w/ 6 levels "1","2","3","4",..: 1 2 3 4 5 6
 $ :'data.frame':       7 obs. of  3 variables:
  ..$ a: num [1:7] 0.507 0.155 0.348 0.660 0.312 ...
  ..$ b: num [1:7]  0.409  1.689  1.587 -0.331 -2.285 ...
  ..$ c: Factor w/ 7 levels "1","2","3","4",..: 1 2 3 4 5 6 7
 $ :'data.frame':       8 obs. of  3 variables:
  ..$ a: num [1:8] 0.706 0.476 0.495 0.308 0.695 ...
  ..$ b: num [1:8]  0.421 -0.400 -1.370  0.988  1.520 ...
  ..$ c: Factor w/ 8 levels "1","2","3","4",..: 1 2 3 4 5 6 7 8
 $ :'data.frame':       9 obs. of  3 variables:
  ..$ a: num [1:9] 0.4822 0.9205 0.0415 0.2940 0.5009 ...
  ..$ b: num [1:9]  1.576 -1.476 -0.145 -0.953  0.407 ...
  ..$ c: Factor w/ 9 levels "1","2","3","4",..: 1 2 3 4 5 6 7 8 9
 $ :'data.frame':       10 obs. of  3 variables:
  ..$ a: num [1:10] 0.938 0.716 0.163 0.476 0.690 ...
  ..$ b: num [1:10] -0.706 -0.161  0.501 -1.014  1.615 ...
  ..$ c: Factor w/ 10 levels "1","2","3","4",..: 1 2 3 4 5 6 7 8 9 10
> x.r <- do.call('rbind', x)
> str(x.r)
'data.frame':   55 obs. of  3 variables:
 $ a: num  0.9863 0.8121 0.0772 0.9702 0.9895 ...
 $ b: num  -0.543 -0.349 -1.008  0.106  0.457 ...
 $ c: Factor w/ 10 levels "1","2","3","4",..: 1 1 2 1 2 3 1 2 3 4 ...
>
>

On 4/29/07, Ajit Pawar <ajitpawar75 at gmail.com> wrote:
> Douglas/R-help,
>        Thanks for your reply. I did try the solution but the result is not
> what I expect and I also get the following warning message:
>
> -------------------
>  Warning message:
>  number of columns of result
>        is not a multiple of vector length (arg 1) in: rbind(1, c(6, 9, 10,
> 12, 13, 14, 19, 22, 29, 30, 42, 45, 47,
>  -------------------
>
>        The "list of data frames" that sapply returns has same number of
> columns *but* different number of rows depending on the index of sapply.
>
>        Any idea what might be going wrong?
>
>        Many thanks in advance!.
>
> Cheers
>
> AP
>
>
>
>
>
>
> On 4/29/07, Douglas Bates <bates at stat.wisc.edu> wrote:
> >
> > On 4/28/07, Ajit Pawar <ajitpawar75 at gmail.com> wrote:
> > > Greetings,
> > >       This might be something very simple but a nice solution eludes
> > me!!
> > >
> > >        I have a function that I call within sapply that generates data
> > frame
> > > in each call. Now when sapply returns me back the result - it's in the
> > form
> > > of a "list of data frames". so in order to extract the information into
> > a
> > > single data frame I have to loop thru the following code:
> > >
> > >        for(i=1:n) {
> > >            my.df = rbind(my.df,list.from.sapply[,i]);
> > >        }
> > >
> > >    Is there anyway to code it better?
> >
> > do.call("rbind", my.df.list.from.sapply)
> >
>
>        [[alternative HTML version deleted]]
>
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>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?