gsub -> replace substring in column

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
project.org] On Behalf Of David Winsemius
Sent: Thursday, August 23, 2012 2:22 AM
To: Paula Cafeld
Cc: r-help at r-project.org
Subject: Re: [R] gsub -> replace substring in column


On Aug 22, 2012, at 10:24 AM, Paula Cafeld wrote:

Hi all,

please excuse- I'm a complete newbie to R, so it's possible my
question was asked a thousand times before, but I don't get it :-( I
imported a CSV file via:

x=read.csv("test.csv",header=TRUE,sep="\t")

In a column there are values with the dot-character (".") I want to
replace with a commata:

You should NOT be trying to do that. R will not recognize such values
as proper numeric values. If you had such values in a text file you
could be using read.csv2 to read them, but once inside R, they will get
displayed with periods. write.table() has a 'dec' argument that lets
you write out results in your preferred format. There are many options
for changing the way the R behaves, but I do not believe that changing
the decimal-point symbol is one of them. Trying typing and read this:

names(options())
?options

David Winsemius, MD
Alameda, CA, USA

x[9]

                   V16
1         GPS LATITUDE
2    53.51982466427600
3   51.520379571037000
4   53.520745152837800
5   51.521750487103766
6    53.52067987059652
7   53.519504773664345
8    51.51861690180330
9   51.519100010776675
10   51.51905431150669
11    51.5193415632712
12   53.51927627894419
13   51.52073862461807
14   50.51989647613406
15   50.51789875702557
16   50.52051666456883

So I tried:

cat(gsub(".",",",x[9],fixed=T))

which outputs:

c(111, 79, 81, 85, 87, 83, 78, 72, 75, 74, 77, 76, 84, 80, 70, 82,
112, 112, 1, 1, 1, 1, 1, 1, 1, 1, 98, 95, 105, 92, 89, 94, 101, 103,
104, 107, 106, 108, 109, 110, 1, 1, 1, 100, 99, 102, 97, 96, 93, 91,
90, 88, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 16, 23, 25, 21, 22,

19,

20, 24, 17, 14, 15, 18, 1, 26, 28, 27, 30, 29, 32, 34, 39, 54, 57,

73,

44, 42, 56, 53, 49, 63, 52, 45, 55, 1, 1, 1, 1, 1, 65, 51, 61, 59,

86,

31, 67, 60, 35, 41, 38, 40, 33, 37, 36, 43, 62, 58, 64, 68, 69, 66,
50, 47, 71, 46, 48, 1, 1, 1, 1, 1, 13, 12, 11, 11, 7, 1, 1, 8, 9, 1,
4, 2, 5, 6, 1, 1, 1, 10, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1)

The values in the column are still unchanged. What have I to do that
the dot will be replaced with the commata?

Thanks in advanced
Paula