| Re: reading header and manipulating according to the header information [message #70993 is a reply to message #70929] |
Sun, 16 May 2010 09:13   |
Gray
Messages: 253
Registered: February 2010
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Senior Member |
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On May 16, 10:31 am, sid <gunvicsi...@gmail.com> wrote:
> On May 15, 9:21 pm, Craig Markwardt <craig.markwa...@gmail.com> wrote:
>
>
>
>
>
>> On May 15, 12:02 pm, Craig Markwardt <craig.markwa...@gmail.com>
>> wrote:
>
>>> On May 15, 10:21 am, sid <gunvicsi...@gmail.com> wrote:> Hi,
>>>> Since I am using huge data of several years, different kind of
>>>> ccds are used on different days. I need to trim the data to a size
>>>> which depends on ccd size, is there any method to read the header
>>>> information and take the ccd size from there and then to proceed
>>>> further, instead of giving the ccd size manually. Because it is really
>>>> very tedious to check for the ccd size each time and then to proceed.
>>>> Please help out.
>>>> For example,
>>>> in one of my data the ccd size that is 1K by 1k is given in header as,
>
>>> ...
>
>>> Anything you can do "manually," you can do in a program. The hard
>>> part is usually to make it robust.
>
>>> Based on the headers you provided, it looks like you have FITS image
>>> files. If you don't already have it, get the IDL Astronomy Library.
>>> It has many routines for reading FITS images and tables. The easiest
>>> one to use is MRDFITS(). MRDFITS() returns the image array which you
>>> can query using SIZE() and then trim as needed.
>
>>> Simple example:
>>> filename = 'myfile.fits'
>>> img = mrdfits(filename) ;; Read image
>>> sz = size(img, /dim) ;; Determine size of image
>>> szx = sz(0) ;; Number of columns
>>> szy = sz(1) ;; Number of rows
>>> img = img( (0+2):(szx-3) , (0+2):(szy-3) ) ;; Remove outermost two
>>> rows and columns
>
>> Oh, and if you need other header keywords, then you need to read the
>> header with a slightly different call to MRDFITS().
>> img = mrdfits(filename,0,header)
>> and then retrieve the keyword KEYNAME with FXPAR()
>> value = fxpar(header, keyname)
>
>> Craig
>
> Thank you this works now i could able to read the size of ccd as a
> variable.
> In my data header I have a line like the one below,
>
> COMMENT = 090222 Lat=40N exp=50s seeing 3",
>
> in this line I need to read the lat=40N that is the value 40 as a idl
> variable which I need use for further analysis,
> but if I do the same process like,img = mrdfits(filename,0,header) and
> value = fxpar(header, comment),
> then it prints the whole sentence '090222 Lat=40N exp=50s seeing
> 3"' .
> So can anyone suggest is there any way to read only the desired part
> of the string.
>
> regards
> sid
STRSPLIT will split the comment into multiple elements, then
WHERE(STREGEX(/Boolean)) will tell you which one you want, then GETTOK
or STRSPLIT will extract the value.
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