This might be obvious but I was wondering if anyone knows quick and easy
way of writing out a CSV file with varying row lengths, ideally an
initial data read from a CSV file which has the same format. See example
below.
I found it quite strange that R cannot write it in one go, so one must
append blocks or post-process the file, is this true? (even Ruby can do
it!!)
Otherwise it puts ,"","" or similar for missing column
values in the
shorter length rows and fill=FALSE option do not work!
I don't want to post-process if possible.
See this post:
http://r.789695.n4.nabble.com/Re-read-csv-trap-td3301924.html
Example that generated Error!
writeLines(c("A,B,C,D",
"1,a,b,c",
"2,f,g,c",
"3,a,i,j",
"4,a,b,c",
"5,d,e,f",
"6,g,h,i,j,k,l,m,n"),
con=file("test.csv"))
read.csv("test.csv")
try(read.csv("test.csv",fill=FALSE))
LEGAL NOTICE
This message is intended for the use o...{{dropped:10}}
The consensus is that it is a very bad idea for a file nominally described as a
CSV file to have a varying numbers of fields from record to record. If you have
need for such a file and go to whatever lengths you need to in order to create
it, please mark it as something other than a CSV file when you are done.
With this in mind, you may be in a better position to understand why the
pre-built facilities do not provide much support in your endeavor.
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Mehmet Suzen <msuzen@mango-solutions.com> wrote:
This might be obvious but I was wondering if anyone knows quick and easy
way of writing out a CSV file with varying row lengths, ideally an
initial data read from a CSV file which has the same format. See example
below.
I found it quite strange that R cannot write it in one go, so one must
append blocks or post-process the file, is this true? (even Ruby can do
it!!)
Otherwise it puts ,"","" or similar for missing column
values in the
shorter length rows and fill=FALSE option do not work!
I don't want to post-process if possible.
See this post:
http://r.789695.n4.nabble.com/Re-read-csv-trap-td3301924.html
Example that generated Error!
writeLines(c("A,B,C,D",
"1,a,b,c",
"2,f,g,c",
"3,a,i,j",
"4,a,b,c",
"5,d,e,f",
"6,g,h,i,j,k,l,m,n"),
con=file("test.csv"))
read.csv("test.csv")
try(read.csv("test.csv",fill=FALSE))
LEGAL NOTICE\ This message is intended for the use o...{...{{dropped:14}}
On 09/28/2011 09:23 AM, Mehmet Suzen wrote:> > This might be obvious but I was wondering if anyone knows quick and easy > way of writing out a CSV file with varying row lengths, ideally an > initial data read from a CSV file which has the same format. See example > below. > > > I found it quite strange that R cannot write it in one go, so one must > append blocks or post-process the file, is this true? (even Ruby can do > it!!) > > Otherwise it puts ,"","" or similar for missing column values in the > shorter length rows and fill=FALSE option do not work! > > I don't want to post-process if possible. > > See this post: > http://r.789695.n4.nabble.com/Re-read-csv-trap-td3301924.html > > Example that generated Error! > > writeLines(c("A,B,C,D", > "1,a,b,c", > "2,f,g,c", > "3,a,i,j", > "4,a,b,c", > "5,d,e,f", > "6,g,h,i,j,k,l,m,n"), > con=file("test.csv")) > > read.csv("test.csv") > try(read.csv("test.csv",fill=FALSE))Hi Mehmet, The example doesn't need to call "file", writeLines does it for you. It worked for me: writeLines(c("A,B,C,D", "1,a,b,c", "2,f,g,c", "3,a,i,j", "4,a,b,c", "5,d,e,f", "6,g,h,i,j,k,l,m,n"), con="test.csv") and to get the original object back, use: readLines("test.csv") The reason you can't use read.csv is that it returns a data frame, and that object can't have elements of unequal length. If you want an object with elements of unequal length, try: as.list(readLines("test.csv")) Jim
Mehmet Suzen <msuzen <at> mango-solutions.com> writes:> This might be obvious but I was wondering if anyone knows quick and easy > way of writing out a CSV file with varying row lengths, ideally an > initial data read from a CSV file which has the same format. See example > below. > > writeLines(c("A,B,C,D", > "1,a,b,c", > "2,f,g,c", > "3,a,i,j", > "4,a,b,c", > "5,d,e,f", > "6,g,h,i,j,k,l,m,n"), > con=file("test.csv")) >X <- read.csv("test.csv") It's not that pretty, but something like tmpf <- function(x) paste(x[nzchar(x)],collapse=",") writeLines(apply(as.matrix(X),1,tmpf),con="outfile.csv") might work