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excel – openxlsx not able to read from .xlsx file in R

Posted by: admin April 23, 2020 Leave a comment

Questions:

I am trying to read value from a .xlsx file using openxlsx package in R. In simple words, I need to write a row of data, which then populates some output cell that has to be read back in R. I will share an example to better explain the problem.

Initial state of the .xlsx file:

enter image description here

I’m now trying to write new values to the cell : A2:A3 = c(“c”, 5). So ideally, I’m expecting A6 = 15

Below is the code used :

require(openxlsx)
path <- "C:/path_to_file/for_SO1.xlsx"
input_row <- c("c", 5)
# Load workbook; create if not existing
wb <- loadWorkbook(path)
# createSheet(wb, name = "1")
writeData(wb, 
          sheet = "Sheet1",
          x = data.frame(input_row),
          startCol=1,
          startRow=1
)  

data_IM <- read.xlsx(wb, 
                     sheet = "Sheet1",
                     rows = c(5,6),
                     cols = c(1))
# Save workbook
saveWorkbook(wb, file = path, overwrite = TRUE)

#> data_IM
#  output_row
#1          3

But I get the inital value(3). However, If i open the .xlsx file, I can see the 15 residing there:

enter image description here

What could be the reason for not able to read this cell? I tried saving it after writing to the file and again reading it but even that failed. openxlsx is the only option I have due to JAVA errors from XLConnect etc.

How to&Answers:
?read.xlsx

Formulae written using writeFormula to a Workbook object will not get
picked up by read.xlsx(). This is because only the formula is written
and left to be evaluated when the file is opened in Excel. Opening,
saving and closing the file with Excel will resolve this.

So the file needs to be opened in Excel and then saved, I can verify that this does work. However this may not be suitable for you.

XLConnect seems to have the desired functionality

# rjava can run out of memory sometimes, this can help.
options(java.parameters = "-Xmx1G")
library(XLConnect)

file_path = "test.xlsx"

input_row <- c("c", 5)

wb <- loadWorkbook(file_path, create=F)
writeWorksheet(wb, 1, startRow = 1, startCol = 1, data = data.frame(input_row))
setForceFormulaRecalculation(wb, 1, TRUE)
saveWorkbook(wb)

# checking
wb <- loadWorkbook(file_path, create=F)
readWorksheet(wb, 1)

Answer:

The file https://cran.r-project.org/web/packages/openxlsx/openxlsx.pdf says

Workbook object will not get picked up by read.xlsx().
This is because only the formula is written and left to be evaluated when the file is opened in Excel.
Opening, saving and closing the file with Excel will resolve this.
So if you are using windows then
save following file vbs file to for example opensaveexcel.vbs

Set objExcel = CreateObject("Excel.Application")
Set objWorkbook = objExcel.Workbooks.Open("D:\Book2.xlsx")
objWorkbook.Save
objWorkbook.Close 
objExcel.Quit
Set objExcel = Nothing
Set objWorkbook = Nothing

and then you can write R code as cell A4 has formula in Book1.xlsx as =A3*5

mywritexlsx(fname="d:/Book1.xlsx",data = 20,startCol = 1,startRow = 3)
system("cp d:\Book1.xlsx d:\Book2.xlsx")
system("cscript //nologo d:\opensaveexcel.vbs")
tdt1=read.xlsx(xlsxFile = "d:/Book1.xlsx",sheet = "Sheet1",colNames = FALSE)
tdt2=read.xlsx(xlsxFile = "d:/Book2.xlsx",sheet = "Sheet1",colNames = FALSE)

Works for me by the way mywritexlsx is as

mywritexlsx<-function(fname="temp.xlsx",sheetname="Sheet1",data,
                  startCol = 1, startRow = 1, colNames = TRUE, rowNames = FALSE)
{
  if(!file.exists(fname))
  {
   wb = openxlsx::createWorkbook()
   sheet = openxlsx::addWorksheet(wb, sheetname)
  }
  else
 {
   wb <- openxlsx::loadWorkbook(file =fname)
   if(!(sum(openxlsx::getSheetNames(fname)==sheetname)))
   sheet = openxlsx::addWorksheet(wb, sheetname)
   else
    sheet=sheetname
  }

  openxlsx::writeData(wb,sheet,data,startCol = startCol, startRow = startRow, 
          colNames = colNames, rowNames = rowNames)
  openxlsx::saveWorkbook(wb, fname,overwrite = TRUE)
}