R help - May 2004 - List of data frames...

Hi, 

I would like to create a list of data frames that I could access via index
manipulation. An array pointer of dataframe...

 for (i in 1:length(InputFilelist))
 {
    # create data.frame
    temp <- read.table (file = InputFilelist[i] , header = T, skip = 4)
    # append data.frame	
    InputDataFrame <<- list(InputDataFrame,temp)
 }

Thanks in advance !
Pascal Rheaume


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Rheaume.Pascal at hydro.qc.ca writes:
> Hi, 
> 
> I would like to create a list of data frames that I could access via index
> manipulation. An array pointer of dataframe...
> 
>  for (i in 1:length(InputFilelist))
>  {
>     # create data.frame
>     temp <- read.table (file = InputFilelist[i] , header = T, skip = 4)
>     # append data.frame	
>     InputDataFrame <<- list(InputDataFrame,temp)
>  }
> 
> Thanks in advance !
You don't want to extend the list on every iteration (it involves
copying the current contents!). 

Try this:

lapply(InputFilelist, read.table, header=TRUE, skip=4)

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907

Rheaume.Pascal at hydro.qc.ca wrote:
> Hi, 
> 
> I would like to create a list of data frames that I could access via index
> manipulation. An array pointer of dataframe...
> 
>  for (i in 1:length(InputFilelist))
>  {
>     # create data.frame
>     temp <- read.table (file = InputFilelist[i] , header = T, skip = 4)
>     # append data.frame	
>     InputDataFrame <<- list(InputDataFrame,temp)
>  }
I think, the following example my help you:

InputDataFrame <- NULL
for (i in 1:3)
{
      # create data.frame
      temp <- data.frame(x=1:5, y=rnorm(5))
      # append data.frame	
      InputDataFrame <- c(InputDataFrame, list(temp))
}

# show the result
str(InputDataFrame)


--
Thomas P.