On Jun 14, 2012, at 10:23 AM, Halldór Björnsson wrote:
Hi,
I am trying to read in weather balloon data, where each file has a
header of fixed length and
a trailing section of a fixed length. The data section (the table)
is of variable length.
An example of the data is on:
http://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT%3ALIST&YEAR=2011&MONTH=06&FROM=1400&TO=1400&STNM=04018
This data has 97 rows and can be read as:
read.table("http://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT%3ALIST&YEAR=2011&MONTH=06&FROM=1400&TO=1400&STNM=04018
",skip=10,nrows=97)
If I set nrows=98 I run into the trailing section.
From day to day the table length changes. Is there a way to get
read.table to always read in the correct
length and just stop when it hits the trailing section?
Looks to be fairly straightforward HTML
inp <- readLines(con=url("http://weather.uwyo.edu/cgi-bin/sounding?region=naconf&TYPE=TEXT%3ALIST&YEAR=2011&MONTH=06&FROM=1400&TO=1400&STNM=04018
"))
> grep("<PRE>", inp)
[1] 6 109
That was followed by multi-line header.
> inp[grep("<PRE>", inp)[1]+4]
[1]
"-----------------------------------------------------------------------------"
The ending can be found similarly:
> grep("</PRE>", inp)
[1] 109 140
datlines <- inp[( grep("<PRE>", inp)[1]+5 ):(grep("</PRE>", inp)[1]-1)]
You may need to use read.fwf for input since the table has missing
values.
--
David Winsemius, MD
West Hartford, CT
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