Description Usage Arguments Details Value Author(s) See Also Examples
write.fwf
writes object in *f*ixed *w*idth *f*ormat.
1 2 3 4 |
x |
data.frame or matrix, the object to be written |
file |
character, name of file or connection, look in
|
append |
logical, append to existing data in |
quote |
logical, quote data in output |
na |
character, the string to use for missing values
i.e. |
sep |
character, separator between columns in output |
rownames |
logical, print row names |
colnames |
logical, print column names |
rowCol |
character, rownames column name |
justify |
character, alignment of character columns; see
|
formatInfo |
logical, return information on number of levels, widths and format |
quoteInfo |
logical, should |
width |
numeric, width of the columns in the output |
eol |
the character(s) to print at the end of each line (row). For example, 'eol="\r\n"' will produce Windows' line endings on a Unix-alike OS, and 'eol="\r"' will produce files as expected by Mac OS Excel 2004. |
qmethod |
a character string specifying how to deal with embedded double quote characters when quoting strings. Must be one of '"escape"' (default), in which case the quote character is escaped in C style by a backslash, or '"double"', in which case it is doubled. You can specify just the initial letter. |
scientific |
logical, if TRUE, allow numeric values to be formatted using scientific notation. |
... |
further arguments to
|
While *F*ixed *w*idth *f*ormat is no longer widely used, it remains common in some disciplines.
Output is similar to print(x)
or format(x)
. Formatting is
done completely by format
on a column basis. Columns in
the output are by default separated with a space i.e. empty column with
a width of one character, but that can be changed with sep
argument as passed to write.table
via ....
As mentioned formatting is done completely by
format
. Arguments can be passed to format
via
...
to further modify the output. However, note that the
returned formatInfo
might not properly account for this, since
format.info
(which is used to collect information about
formatting) lacks the arguments of format
.
quote
can be used to quote fields in the output. Since all
columns of x
are converted to character (via
format
) during the output, all columns will be quoted! If
quotes are used, read.table
can be easily used to read the
data back into R. Check examples. Do read the details about
quoteInfo
argument.
Use only *true* character, i.e., avoid use of tabs, i.e., "\t", or similar
separators via argument sep
. Width of the separator is taken as
the number of characters evaluated via nchar(sep)
.
Use argument na
to convert missing/unknown values. Only single value
can be specified. Use NAToUnknown
prior to export if you need
greater flexibility.
If rowCol
is not NULL
and rownames=TRUE
, rownames
will also have column name with rowCol
value. This is mainly for
flexibility with tools outside R. Note that (at least in R 2.4.0) it
is not "easy" to import data back to R with read.fwf
if
you also export rownames. This is the reason, that default is
rownames=FALSE
.
Information about format of output will be returned if
formatInfo=TRUE
. Returned value is described in value
section. This information is gathered by format.info
and
care was taken to handle numeric properly. If output contains rownames,
values account for this. Additionally, if rowCol
is not
NULL
returned values contain also information about format
of rownames.
If quote=TRUE
, the output is of course wider due to
quotes. Return value (with formatInfo=TRUE
) can account for this
in two ways; controlled with argument quoteInfo
. However, note
that there is no way to properly read the data back to R if
quote=TRUE & quoteInfo=FALSE
arguments were used for
export. quoteInfo
applies only when quote=TRUE
. Assume
that there is a file with quoted data as shown bellow (column numbers in
first three lines are only for demonstration of the values in the
output).
1 2 3 4 5 | 123456789 12345678 # for position
123 1234567 123456 # for width with quoteInfo=TRUE
1 12345 1234 # for width with quoteInfo=FALSE
"a" "hsgdh" " 9"
" " " bb" " 123"
|
With quoteInfo=TRUE
write.fwf
will return
1 2 3 4 | colname position width
V1 1 3
V2 5 7
V3 13 6
|
or (with quoteInfo=FALSE
)
1 2 3 4 | colname position width
V1 2 1
V2 6 5
V3 14 4
|
Argument width
can be used to increase the width of the columns
in the output. This argument is passed to the width argument of
format
function. Values in width
are recycled if
there is less values than the number of columns. If the specified width
is to short in comparison to the "width" of the data in particular
column, error is issued.
Besides its effect to write/export data write.fwf
can provide
information on format and width. A data.frame is returned with the
following columns:
colname |
name of the column |
nlevels |
number of unique values (unused levels of factors are dropped), 0 for numeric column |
position |
starting column number in the output |
width |
width of the column |
digits |
number of digits after the decimal point |
exp |
width of exponent in exponential representation; 0 means
there is no exponential representation, while 1 represents exponent
of length one i.e. |
Gregor Gorjanc
format.info
, format
,
NAToUnknown
, write.table
,
read.fwf
, read.table
and
trim
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 | ## Some data
num <- round(c(733070.345678, 1214213.78765456, 553823.798765678,
1085022.8876545678, 571063.88765456, 606718.3876545678,
1053686.6, 971024.187656, 631193.398765456, 879431.1),
digits=3)
testData <- data.frame(num1=c(1:10, NA),
num2=c(NA, seq(from=1, to=5.5, by=0.5)),
num3=c(NA, num),
int1=c(as.integer(1:4), NA, as.integer(4:9)),
fac1=factor(c(NA, letters[1:9], "hjh")),
fac2=factor(c(letters[6:15], NA)),
cha1=c(letters[17:26], NA),
cha2=c(NA, "longer", letters[25:17]),
stringsAsFactors=FALSE)
levels(testData$fac1) <- c(levels(testData$fac1), "unusedLevel")
testData$Date <- as.Date("1900-1-1")
testData$Date[2] <- NA
testData$POSIXt <- as.POSIXct(strptime("1900-1-1 01:01:01",
format="%Y-%m-%d %H:%M:%S"))
testData$POSIXt[5] <- NA
## Default
write.fwf(x=testData)
## NA should be -
write.fwf(x=testData, na="-")
## NA should be -NA-
write.fwf(x=testData, na="-NA-")
## Some other separator than space
write.fwf(x=testData[, 1:4], sep="-mySep-")
## Force wider columns
write.fwf(x=testData[, 1:5], width=20)
## Show effect of 'scienfic' option
testData$num3 <- testData$num3 * 1e8
write.fwf(testData, scientific=TRUE)
write.fwf(testData, scientific=FALSE)
testData$num3 <- testData$num3 / 1e8
## Write to file and report format and fixed width information
file <- tempfile()
formatInfo <- write.fwf(x=testData, file=file, formatInfo=TRUE)
formatInfo
## Read exported data back to R (note +1 due to separator)
## ... without header
read.fwf(file=file, widths=formatInfo$width + 1, header=FALSE, skip=1,
strip.white=TRUE)
## ... with header - via postimport modfication
tmp <- read.fwf(file=file, widths=formatInfo$width + 1, skip=1,
strip.white=TRUE)
colnames(tmp) <- read.table(file=file, nrow=1, as.is=TRUE)
tmp
## ... with header - persuading read.fwf to accept header properly
## (thanks to Marc Schwartz)
read.fwf(file=file, widths=formatInfo$width + 1, strip.white=TRUE,
skip=1, col.names=read.table(file=file, nrow=1, as.is=TRUE))
## ... with header - with the use of quotes
write.fwf(x=testData, file=file, quote=TRUE)
read.table(file=file, header=TRUE, strip.white=TRUE)
## Tidy up
unlink(file)
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