[R] Changing a value in a particular row and column within a text file

[Mauricio Zambrano]

Thank you very much for all your help.

Following your advice, I solved my problem by using the following:

##########################################

lines    <- readLines("myFile.txt")
myline <- lines[myrow]
L         <- nchar(myline)

substr(myline, Col.Ini, Col.Fin) <- NewValue
lines[myrow]                               <- myline
readLines(lines, "myFile.txt")

############################################

The 'readLines' was the only R command that I was missing from other
programming languages, but now I can implement in R the full code in
which I was working. :)

Thanks for your fast and good answer, That's one of the thinks that I
like the most of the R community !.

Kind regards,

Mauricio

-- 
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Linux user #454569 -- Ubuntu user #17469
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2010/12/17 Petr Savicky <savicky at cs.cas.cz>:
> On Fri, Dec 17, 2010 at 01:49:23AM -0800, T.V. Nguyen wrote:
>> On 17 Dec 2010, at 01:13, Mauricio Zambrano wrote:
> [...]
>> > but some text, and I now exactly the row that has to be modified and
>> > the columns within that row that have to be changed with a new
>> > numerical value.
> [...]
>> You can either edit the line you want manually, or use sub to make changes:
>>
>> > sub("Lords-a-Leaping","Jaffa Cakes",list)
>> > head(list)
>> [1] "12 Drummers Drumming" "11 Pipers Piping"
>> [3] "10 Jaffa Cakes"       "9 Ladies Dancing"
>> [5] "8 Maids-a-Milking"    "7 Swans-a-Swimming"
>
> Additionally, if you know the exact character positions, which have
> to be changed, then substr() can be used.
>
>  x <- "123456789"
>  substr(x, 5, 7) <- "abc"
>  x # [1] "1234abc89"
>
> For an exact replacement, the length of the new text should be
> the same as of the original field.
>
> Petr Savicky.
>
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