read.xlsx: Read the contents of a worksheet into an R data.frame

Description Usage Arguments Details Value Author(s) See Also Examples

View source: R/read.xlsx.R

Description

Read the contents of a worksheet into an R data.frame.

Usage

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read.xlsx(file, sheetIndex, sheetName=NULL, rowIndex=NULL,
  startRow=NULL, endRow=NULL, colIndex=NULL,
  as.data.frame=TRUE, header=TRUE, colClasses=NA,
  keepFormulas=FALSE, encoding="unknown", password=NULL, ...)

read.xlsx2(file, sheetIndex, sheetName=NULL, startRow=1,
  colIndex=NULL, endRow=NULL, as.data.frame=TRUE, header=TRUE,
  colClasses="character", password=NULL, ...)

Arguments

file

the path to the file to read.

sheetIndex

a number representing the sheet index in the workbook.

sheetName

a character string with the sheet name.

rowIndex

a numeric vector indicating the rows you want to extract. If NULL, all rows found will be extracted, unless startRow or endRow are specified.

colIndex

a numeric vector indicating the cols you want to extract. If NULL, all columns found will be extracted.

as.data.frame

a logical value indicating if the result should be coerced into a data.frame. If FALSE, the result is a list with one element for each column.

header

a logical value indicating whether the first row corresponding to the first element of the rowIndex vector contains the names of the variables.

colClasses

For read.xlsx a character vector that represent the class of each column. Recycled as necessary, or if the character vector is named, unspecified values are taken to be NA. For read.xlsx2 see readColumns.

keepFormulas

a logical value indicating if Excel formulas should be shown as text in R and not evaluated before bringing them in.

encoding

encoding to be assumed for input strings. See read.table.

startRow

a number specifying the index of starting row. For read.xlsx this argument is active only if rowIndex is NULL.

endRow

a number specifying the index of the last row to pull. If NULL, read all the rows in the sheet. For read.xlsx this argument is active only if rowIndex is NULL.

password

a String with the password.

...

other arguments to data.frame, for example stringsAsFactors

Details

The read.xlsx function provides a high level API for reading data from an Excel worksheet. It calls several low level functions in the process. Its goal is to provide the conveniency of read.table by borrowing from its signature.

The function pulls the value of each non empty cell in the worksheet into a vector of type list by preserving the data type. If as.data.frame=TRUE, this vector of lists is then formatted into a rectangular shape. Special care is needed for worksheets with ragged data.

An attempt is made to guess the class type of the variable corresponding to each column in the worksheet from the type of the first non empty cell in that column. If you need to impose a specific class type on a variable, use the colClasses argument. It is recommended to specify the column classes and not rely on R to guess them, unless in very simple cases.

Excel internally stores dates and datetimes as numeric values, and does not keep track of time zones and DST. When a datetime column is brought into R, it is converted to POSIXct class with a GMT timezone. Occasional rounding errors may appear and the R and Excel string representation my differ by one second. For read.xlsx2 bring in a datetime column as a numeric one and then convert to class POSIXct or Date. Also rounding the POSIXct column in R usually does the trick too.

The read.xlsx2 function does more work in Java so it achieves better performance (an order of magnitude faster on sheets with 100,000 cells or more). The result of read.xlsx2 will in general be different from read.xlsx, because internally read.xlsx2 uses readColumns which is tailored for tabular data.

Reading of password protected workbooks is supported for Excel 2007 OOXML format only.

Value

A data.frame or a list, depending on the as.data.frame argument. If some of the columns are read as NA's it's an indication that the colClasses argument has not been set properly.

If the sheet is empty, return NULL. If the sheet does not exist, return an error.

Author(s)

Adrian Dragulescu

See Also

write.xlsx for writing xlsx documents. See also readColumns for reading only a set of columns into R.

Examples

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## Not run: 

file <- system.file("tests", "test_import.xlsx", package = "xlsx")
res <- read.xlsx(file, 1)  # read first sheet
head(res)
#          NA. Population Income Illiteracy Life.Exp Murder HS.Grad Frost   Area
# 1    Alabama       3615   3624        2.1    69.05   15.1    41.3    20  50708
# 2     Alaska        365   6315        1.5    69.31   11.3    66.7   152 566432
# 3    Arizona       2212   4530        1.8    70.55    7.8    58.1    15 113417
# 4   Arkansas       2110   3378        1.9    70.66   10.1    39.9    65  51945
# 5 California      21198   5114        1.1    71.71   10.3    62.6    20 156361
# 6   Colorado       2541   4884        0.7    72.06    6.8    63.9   166 103766
# >


# To convert an Excel datetime colum to POSIXct, do something like:
#   as.POSIXct((x-25569)*86400, tz="GMT", origin="1970-01-01")
# For Dates, use a conversion like:
#   as.Date(x-25569, origin="1970-01-01") 

res2 <- read.xlsx2(file, 1)  


## End(Not run)

colearendt/xlsx documentation built on Oct. 11, 2018, 12:23 a.m.