R help - May 2011 - Creating dataframes

I would like to create a certain number of dataframes out of one dataframe
where each of the dataframes
is related to a factor. This should be possible with a loop or a function,
as is very clumsy to do it manually
when there are quite a lot factors. 

For example having a dataframe called "exmpl":

Site	Value
1	12
1	15	
1	18
1	21	
1	12
1	13
2	15	
2	12
2	58
2	62
2	22
2	65
2	29
3	21
3	55
3	11
3	98

I would like to create 3 dataframes, where  
"exmpl_01" equals:
1	12
1	15	
1	18
1	21	
1	12
1	13

"exmpl_02" equals:
2	15	
2	12
2	58
2	62
2	22
2	65
2	29

"exmpl_03" equals:
3	21
3	55
3	11
3	98

Thanks for any help.
Walter

--
View this message in context:
http://r.789695.n4.nabble.com/Creating-dataframes-tp3520509p3520509.html
Sent from the R help mailing list archive at Nabble.com.

The way to do what you want is to use the split function, for
example,

mydataframes = split(exmpl,exmpl$Site)

This will return a list with all the data frames.

If you don't understand why this is a better solution than 
creating many separate data frames, let us know what you plan
to do with the data frames you're creating.

                                                    - Phil



On Fri, 13 May 2011, Woida71 wrote:
> I would like to create a certain number of dataframes out of one dataframe
> where each of the dataframes
> is related to a factor. This should be possible with a loop or a function,
> as is very clumsy to do it manually
> when there are quite a lot factors.
>
> For example having a dataframe called "exmpl":
>
> Site	Value
> 1	12
> 1	15
> 1	18
> 1	21
> 1	12
> 1	13
> 2	15
> 2	12
> 2	58
> 2	62
> 2	22
> 2	65
> 2	29
> 3	21
> 3	55
> 3	11
> 3	98
>
> I would like to create 3 dataframes, where
> "exmpl_01" equals:
> 1	12
> 1	15
> 1	18
> 1	21
> 1	12
> 1	13
>
> "exmpl_02" equals:
> 2	15
> 2	12
> 2	58
> 2	62
> 2	22
> 2	65
> 2	29
>
> "exmpl_03" equals:
> 3	21
> 3	55
> 3	11
> 3	98
>
> Thanks for any help.
> Walter
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Creating-dataframes-tp3520509p3520509.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.
>

On May 13, 2011, at 10:28 AM, Woida71 wrote:
> I would like to create a certain number of dataframes out of one dataframe
> where each of the dataframes
> is related to a factor. This should be possible with a loop or a function,
> as is very clumsy to do it manually
> when there are quite a lot factors. 
> 
> For example having a dataframe called "exmpl":
> 
> Site	Value
> 1	12
> 1	15	
> 1	18
> 1	21	
> 1	12
> 1	13
> 2	15	
> 2	12
> 2	58
> 2	62
> 2	22
> 2	65
> 2	29
> 3	21
> 3	55
> 3	11
> 3	98
> 
> I would like to create 3 dataframes, where  
> "exmpl_01" equals:
> 1	12
> 1	15	
> 1	18
> 1	21	
> 1	12
> 1	13
> 
> "exmpl_02" equals:
> 2	15	
> 2	12
> 2	58
> 2	62
> 2	22
> 2	65
> 2	29
> 
> "exmpl_03" equals:
> 3	21
> 3	55
> 3	11
> 3	98
> 
> Thanks for any help.
> Walter

The easiest way is to create a list of data frames using:
> DF
   Site Value
1     1    12
2     1    15
3     1    18
4     1    21
5     1    12
6     1    13
7     2    15
8     2    12
9     2    58
10    2    62
11    2    22
12    2    65
13    2    29
14    3    21
15    3    55
16    3    11
17    3    98

> split(DF, DF$Site)
$`1`
  Site Value
1    1    12
2    1    15
3    1    18
4    1    21
5    1    12
6    1    13

$`2`
   Site Value
7     2    15
8     2    12
9     2    58
10    2    62
11    2    22
12    2    65
13    2    29

$`3`
   Site Value
14    3    21
15    3    55
16    3    11
17    3    98


See ?split for more information.

HTH,

Marc Schwartz