R help - Nov 2009 - Reading a data file one record at a time [SEC=UNCLASSIFIED]

Dear r-help,

I have a radar data file in the following format:

nrays
for (1 to n_rays)
{ some_data_info
  for (1 to n_gates)
  { some_data_info}
}

N_rays=360 and n_gates=950

The data looks something like:

    Header line1
    Ray1 header
        gate1 var1, var2,.....,varN
        ...
        gate950 var1, var2,.....,varN
    Ray2 header
        gate1 var1, var2,.....,varN
        ...
        gate950 var1, var2,.....,varN
    ...
    ...
    ...
   Ray360 header
       gate1 var1, var2,.....,varN
        ...
       gate950 var1, var2,.....,varN

I am having trouble reading this data. Are there any suggestions on how to read
the data file one block (corresponding to one ray) at a time?

Any help appreciated.

Regards,
Justin


~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Justin R. Peter
Research Scientist
Queensland Climate Change Centre of Excellence
based at
Centre for Australian Weather and Climate Research (CAWCR),
A partnership between the Australian Bureau of Meteorology and CSIRO

e: j.peter@bom.gov.au<mailto:j.peter@bom.gov.au>
p: +61 (0) 3 9669 4838
f: +61 (0) 3 9669 4660
s: Level 9
Bureau of Meteorology Building
700 Collins Street
Docklands
VIC 3008
Australia
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



	[[alternative HTML version deleted]]

try this:
> input <- readLines(textConnection("header line
+ Ray1 header
+ gate1 1,2,3,4,5,6,7
+ gate2 5,6,7,8,9,0
+ Ray2 header
+ gate1 5,4,3,2,1
+ gate2 8,7,6,5,4,34"))
> closeAllConnections()
> # delete first header line
> input <- input[-1]
>
> # read the data one line at a time, parsing the data
> result <- list()
> for (line in input){
+     # strip leading blanks
+     line <- sub("^ *", "", line)
+     x <- strsplit(line, ' ')[[1]]
+     if (x[2] == 'header'){
+         key <- x[1]  # save 'Rayn' as key to data
+         next
+     }
+     result[[key]][x[1]] <- list(as.numeric(strsplit(x[2],
',')[[1]]))
+ }
>
> result
$Ray1
$Ray1$gate1
[1] 1 2 3 4 5 6 7

$Ray1$gate2
[1] 5 6 7 8 9 0


$Ray2
$Ray2$gate1
[1] 5 4 3 2 1

$Ray2$gate2
[1]  8  7  6  5  4 34




On Thu, Nov 12, 2009 at 1:02 AM, Justin Peter <J.Peter at bom.gov.au>
wrote:
> Dear r-help,
>
> I have a radar data file in the following format:
>
> nrays
> for (1 to n_rays)
> { some_data_info
> ?for (1 to n_gates)
> ?{ some_data_info}
> }
>
> N_rays=360 and n_gates=950
>
> The data looks something like:
>
> ? ?Header line1
> ? ?Ray1 header
> ? ? ? ?gate1 var1, var2,.....,varN
> ? ? ? ?...
> ? ? ? ?gate950 var1, var2,.....,varN
> ? ?Ray2 header
> ? ? ? ?gate1 var1, var2,.....,varN
> ? ? ? ?...
> ? ? ? ?gate950 var1, var2,.....,varN
> ? ?...
> ? ?...
> ? ?...
> ? Ray360 header
> ? ? ? gate1 var1, var2,.....,varN
> ? ? ? ?...
> ? ? ? gate950 var1, var2,.....,varN
>
> I am having trouble reading this data. Are there any suggestions on how to
read the data file one block (corresponding to one ray) at a time?
>
> Any help appreciated.
>
> Regards,
> Justin
>
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Dr. Justin R. Peter
> Research Scientist
> Queensland Climate Change Centre of Excellence
> based at
> Centre for Australian Weather and Climate Research (CAWCR),
> A partnership between the Australian Bureau of Meteorology and CSIRO
>
> e: j.peter at bom.gov.au<mailto:j.peter at bom.gov.au>
> p: +61 (0) 3 9669 4838
> f: +61 (0) 3 9669 4660
> s: Level 9
> Bureau of Meteorology Building
> 700 Collins Street
> Docklands
> VIC 3008
> Australia
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?