[R] How to read only specified columns from a data file

[Luis Ridao]

David,

Thanks for your tip but it seems I'm having problems with the number
of columns R manages to read in. Below it s an example of the data read in:

> inp[1:20,]
        V1          V2        V3       V4     V5     V6     V7     V8     V9
1   1.0000 log_fy_coff -1.007600 0.119520 1.0000     NA            NA     NA
2   2.0000 log_fy_coff -0.935010 0.112840 0.8896 1.0000            NA     NA
3   3.0000 log_fy_coff -0.876260 0.107500 0.8219 0.8847 1.0000     NA     NA
4   4.0000 log_fy_coff -0.683090 0.103030 0.7656 0.8143 0.8747 1.0000     NA
5   5.0000 log_fy_coff -0.623500 0.100980 0.7206 0.7636 0.8086 0.8764 1.0000
6   6.0000 log_fy_coff -0.583330 0.098978 0.6819 0.7214 0.7615 0.8150 0.8762
7   1.0000                    NA       NA     NA     NA            NA     NA
8   7.0000 log_fy_coff -0.676790 0.096608 0.6521 0.6892 0.7254 0.7719 0.8148
9   0.8717      1.0000        NA       NA     NA     NA            NA     NA
10  8.0000 log_fy_coff -0.696060 0.093761 0.6297 0.6654 0.6988 0.7405 0.7750
11  0.8116      0.8643  1.000000       NA     NA     NA            NA     NA
12  9.0000 log_fy_coff -0.527060 0.089949 0.6003 0.6347 0.6667 0.7060 0.7367

as you see there are only 9 columns in inp and the rest is read in in
the following row(see row 7)
I just don't understand why this is happening (using fill=T does not
help either)

Best,
Luis

On Tue, Mar 15, 2011 at 5:15 PM, David Winsemius <dwinsemius at comcast.net> wrote:
>
> On Mar 15, 2011, at 1:11 PM, <rex.dwyer at syngenta.com> wrote:
>
>> I think you need to read an introduction to R.
>> For starters, read.table returns its results as a value, which you are not
>> saving.
>> The probable answer to your question:
>> Read the whole file with read.table, and select columns you need, e.g.:
>> tab <- read.table(myfile, skip=2)[,1:5]
>>
>> -----Original Message-----
>> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
>> On Behalf Of Luis Ridao
>> Sent: Tuesday, March 15, 2011 11:53 AM
>> To: r-help at r-project.org
>> Subject: [R] How to read only specified columns from a data file
>>
>> R-help,
>>
>> I'm trying to read a data file with plenty of columns.
>> I just need the first 5 but it doe not work by doing something like:
>>
>>> mycols <- rep(NULL, 430) ; mycols[c(1:4)] <- NA
>>> read.table(myfile, skip=2, colClasses=mycols)
>
> I would have suggested:
>
> mycols <- rep(NULL, 430) ; mycols[1:5] <- rep("numeric", 5)
> inp <- read.table(myfile, skip=2, colClasses=mycols)
> head(inp)
>
> --
> David.
>
>>
>> Any suggestions?
>>
>> Thanks in advance
>>
>> ______________________________________________
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>> and provide commented, minimal, self-contained, reproducible code.
>>
>>
>>
>>
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>> PLEASE do read the posting guide
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>
> David Winsemius, MD
> West Hartford, CT
>
>