| defining structure after ascii template [message #85878] |
Mon, 16 September 2013 08:56  |
spluque
Messages: 33
Registered: September 2013
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Member |
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Hello,
As far as I can see, it is not possible to define a structure using a template as the one built via ascii_template(). Essentially, extract a sub-structure from the template returned by ascii_template, containing the column names as tags and the field type. What is the proper way to do this?
Thanks,
Seb
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| Re: defining structure after ascii template [message #85880 is a reply to message #85879] |
Mon, 16 September 2013 10:02  |
spluque
Messages: 33
Registered: September 2013
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Member |
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On Monday, September 16, 2013 11:02:11 AM UTC-5, David Fanning wrote:
> spluque@gmail.com writes:
>
>
>
>> As far as I can see, it is not possible to define a structure using a template as the one built via ascii_template(). Essentially, extract a sub-structure from the template returned by ascii_template, containing the column names as tags and the field type. What is the proper way to do this?
>
>
>
> I honestly have no idea what this question means. Why don't you explain
>
> to us what you are trying to do.
Sorry for the terse initial post. Here is what I am trying to do:
1. I've prepared a template with ascii_template() for reading in an ASCII file via read_ascii().
2. Before reading the data with read_ascii(), I need to prepare an *array* of structures, where each element is a record (row) in a number of files to be read with the template in (1).
3. read_ascii() creates a structure that looks like this:
help, data, /structures
** Structure <57e3008>, 23 tags, length=7800864, data length=7800864, refs=1:
FIELD01 LONG Array[84792]
FIELD02 FLOAT Array[84792]
FIELD03 LONG Array[84792]
...[many more fields]
So the array of structures to be created would like this (abbreviating the number of fields for brevity here):
p={'foo', FIELD01:0L, FIELD02:0.0, FIELD03:0L}
replicate(p, n_recs)
where n_recs is the total number of records expected.
So the question is how can p be created from the information already there in the template created in (1)?
Thanks,
Seb
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| Re: defining structure after ascii template [message #85882 is a reply to message #85880] |
Mon, 16 September 2013 10:24 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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spluque@gmail.com writes:
>
> On Monday, September 16, 2013 11:02:11 AM UTC-5, David Fanning wrote:
>> spluque@gmail.com writes:
>>
>>
>>
>>> As far as I can see, it is not possible to define a structure using a template as the one built via ascii_template(). Essentially, extract a sub-structure from the template returned by ascii_template, containing the column names as tags and the field type. What is the proper way to do this?
>>
>>
>>
>> I honestly have no idea what this question means. Why don't you explain
>>
>> to us what you are trying to do.
>
> Sorry for the terse initial post. Here is what I am trying to do:
>
> 1. I've prepared a template with ascii_template() for reading in an ASCII file via read_ascii().
>
> 2. Before reading the data with read_ascii(), I need to prepare an *array* of structures, where each element is a record (row) in a number of files to be read with the template in (1).
>
> 3. read_ascii() creates a structure that looks like this:
>
> help, data, /structures
> ** Structure <57e3008>, 23 tags, length=7800864, data length=7800864, refs=1:
> FIELD01 LONG Array[84792]
> FIELD02 FLOAT Array[84792]
> FIELD03 LONG Array[84792]
> ...[many more fields]
>
> So the array of structures to be created would like this (abbreviating the number of fields for brevity here):
>
> p={'foo', FIELD01:0L, FIELD02:0.0, FIELD03:0L}
> replicate(p, n_recs)
>
> where n_recs is the total number of records expected.
>
> So the question is how can p be created from the information already there in the template created in (1)?
Well, p *is* the structure you obtained. I guess I don't see the
problem:
IDL> struct = ascii_template()
IDL> help, struct
** Structure <701c24d0>, 10 tags, length=320, data length=313, refs=1:
VERSION FLOAT 1.00000
DATASTART LONG 0
DELIMITER BYTE 32
MISSINGVALUE FLOAT NaN
COMMENTSYMBOL STRING ''
FIELDCOUNT LONG 10
FIELDTYPES LONG Array[10]
FIELDNAMES STRING Array[10]
FIELDLOCATIONS LONG Array[10]
FIELDGROUPS LONG Array[10]
IDL> data = Replicate(struct, 100)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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| Re: defining structure after ascii template [message #85884 is a reply to message #85882] |
Mon, 16 September 2013 10:51 |
spluque
Messages: 33
Registered: September 2013
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Member |
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On Monday, September 16, 2013 12:24:29 PM UTC-5, David Fanning wrote:
> spluque@gmail.com writes:
>
>
>
>>
>
>> On Monday, September 16, 2013 11:02:11 AM UTC-5, David Fanning wrote:
>
>>> spluque@gmail.com writes:
>
>>>
>
>>>
>
>>>
>
>>>> As far as I can see, it is not possible to define a structure using a template as the one built via ascii_template(). Essentially, extract a sub-structure from the template returned by ascii_template, containing the column names as tags and the field type. What is the proper way to do this?
>
>>>
>
>>>
>
>>>
>
>>> I honestly have no idea what this question means. Why don't you explain
>
>>>
>
>>> to us what you are trying to do.
>
>>
>
>> Sorry for the terse initial post. Here is what I am trying to do:
>
>>
>
>> 1. I've prepared a template with ascii_template() for reading in an ASCII file via read_ascii().
>
>>
>
>> 2. Before reading the data with read_ascii(), I need to prepare an *array* of structures, where each element is a record (row) in a number of files to be read with the template in (1).
>
>>
>
>> 3. read_ascii() creates a structure that looks like this:
>
>>
>
>> help, data, /structures
>
>> ** Structure <57e3008>, 23 tags, length=7800864, data length=7800864, refs=1:
>
>> FIELD01 LONG Array[84792]
>
>> FIELD02 FLOAT Array[84792]
>
>> FIELD03 LONG Array[84792]
>
>> ...[many more fields]
>
>>
>
>> So the array of structures to be created would like this (abbreviating the number of fields for brevity here):
>
>>
>
>> p={'foo', FIELD01:0L, FIELD02:0.0, FIELD03:0L}
>
>> replicate(p, n_recs)
>
>>
>
>> where n_recs is the total number of records expected.
>
>>
>
>> So the question is how can p be created from the information already there in the template created in (1)?
>
>
>
> Well, p *is* the structure you obtained. I guess I don't see the
>
> problem:
>
>
>
> IDL> struct = ascii_template()
>
> IDL> help, struct
>
> ** Structure <701c24d0>, 10 tags, length=320, data length=313, refs=1:
>
> VERSION FLOAT 1.00000
>
> DATASTART LONG 0
>
> DELIMITER BYTE 32
>
> MISSINGVALUE FLOAT NaN
>
> COMMENTSYMBOL STRING ''
>
> FIELDCOUNT LONG 10
>
> FIELDTYPES LONG Array[10]
>
> FIELDNAMES STRING Array[10]
>
> FIELDLOCATIONS LONG Array[10]
>
> FIELDGROUPS LONG Array[10]
>
> IDL> data = Replicate(struct, 100)
Thanks for your patience David. The problem is that the template structure is not quite the same as the one created by read_ascii(); compare the output you got with the one in point (2) of my previous message. In other words, what I need to replicate is an element of the output of read_ascii(), but without having to call it first. Hopefully, this is clearer.
Cheers,
Seb
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