[R] automatic convert list to dataframe

[Rui Barradas]

Hello,

Here are two more attempts at solving the problem.

1. Instead of having 30-40 data.frames per file in the globalenv, not a 
good idea, the following code will create as many lists as you have 
files and each list is a list of df's.


temp_list <- vector("list", length = length(filenames))
for(i in seq_along(filenames)){
   xlfile <- filenames[i]
   temp_list[[i]] <- import_list(paste0(xlfile, ".xlsx"))
}
list2env(temp_list, envir = .GlobalEnv)
rm(temp_list)

Now you can access the data with code like


file1$dx1       # a data.frame, first sheet in excel file1
file1[["dx1"]]  # equivalent


2. I cannot see a reason why the following shouldn't work. It creates 
lots of data.frames in the globalenv, 30-40 per file. This makes the 
globalenv messy and is not recommended.


temp_list <- vector("list", length = length(filenames))
for(i in seq_along(filenames)){
   # import the data
   xlfile <- filenames[i]
   temp_list[[i]] <- import_list(paste0(xlfile, ".xlsx"))
   # now take care of the names
   new_names <- paste(xlfile, names(temp_list[[i]]), sep = "_")
   names(temp_list[[i]]) <- new_names
   # create the current data.frames in the globalenv
   list2env(temp_list[[i]], envir = .GlobalEnv)
}
rm(temp_list)


Hope this helps,

Rui Barradas


Às 20:51 de 03/10/2022, Kai Yang escreveu:
>   Hi Rui,
> I copied "list2env(i, envir = .GlobalEnv)" to the code, but I got the same error message of "first argument must be a named list". Maybe list2env cannot put in loop? the code works very well outside of for loop.
> One more thing, the difference file may have same sheet name. that's why I want to add file name in front of sheet name to avoid overwriting. It still works well outside of loop, but doesn't work in loop. I don't know how to fix the problems.
> Thank you,
> Kai
> 
>      On Monday, October 3, 2022 at 12:09:04 PM PDT, Rui Barradas <ruipbarradas using sapo.pt> wrote:
>   
>   Hello,
> 
> If in each iteration i is a list, try removing the call to names().
> Try, in the loop,
> 
> 
> list2env(i, envir = .GlobalEnv)
> 
> 
> The error message is telling that list2env's first argument must be a
> named list and names(i) is an unnamed vector, it's i that's the named
> list (you even changed its names in the previous instruction).
> 
> Hope this helps,
> 
> Rui Barradas
> 
> Às 18:38 de 03/10/2022, Kai Yang escreveu:
>>    Hi Rui,
>> list2env(file1, envir = .GlobalEnv) is worked very well. Thank you.
>>
>> But when I tried to put the sample code  into for loop. I got error message:
>> for(i in filenames){
>>      assign(i, import_list(paste0(i, ".xlsx", sep="")))
>>      names(i) <- paste(i, names(i), sep = "_")
>>      list2env(names(i), envir = .GlobalEnv)
>> }
>> Error in list2env(names(i), envir = .GlobalEnv) :   first argument must be a named list
>>
>> It seems I cannot put names(i) into for loop, Could you please help me to debug it?
>> Thank you,Kai    On Monday, October 3, 2022 at 10:14:25 AM PDT, Rui Barradas <ruipbarradas using sapo.pt> wrote:
>>    
>>    Hello,
>>
>>
>> list2env(file1, envir = .GlobalEnv)
>>
>>
>> will create data.frames dx1, dx2, etc, in the global environment.
>> If you really need the names file1_dx1, file1_dx2, etc, you can first
>> change the names
>>
>>
>> names(file1) <- paste("file1", names(file1), sep = "_")
>>
>>
>> and then run list2env like above.
>>
>> Hope this helps,
>>
>> Rui Barradas
>>
>> Às 16:51 de 03/10/2022, Kai Yang via R-help escreveu:
>>> Hi R team,
>>> I can use rio package to read excel file into R as a list. The excel file content multiple sheets (30 - 40 data sheets). I can convert each data elements into dataframe manually. I have multiple excel files with multiple data sheets. I need to load them into R and do the comparison for same sheet name from difference excel file. My current code is:
>>>      library(rio)   setwd ("C:/temp")
>>> filenames <- gsub("\\.xlsx$","", list.files(pattern="\\.xlsx$"))
>>> for(i in filenames){
>>>        assign(i, import_list(paste0(i, ".xlsx", sep="")))
>>> }
>>> file1_dx1     <-  file1[["dx1"]]
>>>
>>> file1_dx2     <-  file1[["dx2"]]
>>>
>>> file1_dx3     <-  file1[["dx3"]]
>>>
>>> file2_dx1     <-  file1[["dx1"]]
>>>
>>> file2_dx2     <-  file1[["dx2"]]
>>> ......
>>>
>>> I hope the code can automatic converting the list (may have 30 - 40 lists) by adding file name (such as: filename_sheetname) and put it in for loop
>>>
>>>
>>> Thank you,
>>> Kai
>>>
>>>
>>>
>>>
>>>        [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
>>> 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.
>>      
>