| Re: READ_ASCII - accessing data from structures [message #39366] |
Wed, 12 May 2004 13:25 |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Wed, 12 May 2004 11:44:09 -0600, David Fanning wrote:
> Martin Doyle writes:
>
>> I wonder if anyone might be able to help me with this?
>>
>> I'm using the IDL READ_ASCII function to read in a semicolon seperated
>> file, after which I'd like to access individual elements of that data
>> file. From the RSI website, I see that I can access the data fields
>> (i.e. each column of data) by using, for example;
>>
>> print, mydata.(4)
>>
>> using the Variable_Name.(Tag_Index) method.
>>
>> Could someone tell me how to get to the individual elements of
>> mydata.(4)?? Using the above I can only get a large stream of numbers,
>> I need to use them one by one.
>
> Well, this should work:
>
> Print, (mydata.(4))[5]
Just wanted to point out that mydata[5].(4) will typically be quicker
if the mydata vector is quite long, and also requires fewer
parentheses. Your method first creates a (potentially long) vector,
and then subscripts it.
JD
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| Re: READ_ASCII - accessing data from structures [message #39370 is a reply to message #39366] |
Wed, 12 May 2004 10:44  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Martin Doyle writes:
> I wonder if anyone might be able to help me with this?
>
> I'm using the IDL READ_ASCII function to read in a semicolon seperated
> file, after which I'd like to access individual elements of that data
> file. From the RSI website, I see that I can access the data fields
> (i.e. each column of data) by using, for example;
>
> print, mydata.(4)
>
> using the Variable_Name.(Tag_Index) method.
>
> Could someone tell me how to get to the individual elements of
> mydata.(4)?? Using the above I can only get a large stream of numbers,
> I need to use them one by one.
Well, this should work:
Print, (mydata.(4))[5]
But usually, you would just pull the column off and treat
it as an array, unless you had some speciific memory
considerations:
col4 = Reform(mydata.(4))
print, col4[5]
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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