tomandwilltamu08@gmail.com writes:
> Hi IDL gurus,
>
> I am having a hard time thinking of how to read in the following
> data... Its an ascii file. It has hundreds of sections with a title,
> then a table of numbers, then another string with a different table of
> a different size like so:
>
> One name
> 1 42 3.14 Blah
> 2 77 4.13 String
>
> Another name
> 1 11 1.34 String
> 2 22 1.43 Blah
> 3 33 3.41 String
>
> Third name
> 1 44 1.23 Something
> 2 55 2.34 String
> 3 66 3.45 String
> 4 77 4.56 String
> 5 88 5.67 String
>
> ...... and there are hundreds of these . The number of columns is
> fixed, but the number of rows is variable.
>
> What would be a good way to read this in in IDL? Is there a good way
> that I could read them in one by one? I obviously can't specify the
> number of rows of each array a priori, but I could possibly specify
> the total number of arrays ahead of time.
OK, how about this. I just saved your example data in
a file named data.txt, and I wrote the following code to
read the data.
FUNCTION UnpackData, dataStruct
struct = {int_1:0L, int_2:0L, float_1:0.0, str:""}
d = Replicate(struct, N_Elements(*dataStruct.ptr))
FOR j=0,N_Elements(d)-1 DO BEGIN
parts = StrSplit((*dataStruct.ptr)[j], /Extract)
d[j].int_1 = Long(parts[0])
d[j].int_2 = Long(parts[1])
d[j].float_1 = Float(parts[2])
d[j].str = parts[3]
ENDFOR
RETURN, d
END ;--------------------------------------------------------
lines = File_Lines(file)
d = StrArr(lines)
openr, 1, file
readf, 1, d
close, 1
index = where(d EQ "", count)
index = [index, N_Elements(d)]
data = Replicate({name:"", ptr:Ptr_New()}, count+1)
startIndex = 0
FOR j=0, count DO BEGIN
endIndex = index[j] - 1
data[j].name = d[startIndex]
data[j].ptr = Ptr_New(d[startIndex+1:endIndex])
startIndex = index[j]+1
ENDFOR
END
This consists of a main level program that reads the data file,
and a function UnpackData that unpacks the data that you have
read. I envision it working like this. Suppose you save this
to a file name readit.pro.
IDL> .compile readit
IDL> file = 'data.txt'
IDL> .go
IDL> Print, 'Number of data units read: ', N_Elements(data)
Number of data units read: 3
IDL> a = UnpackData(data[0])
IDL> FOR j= 0,N_Elements(a)-1 DO Help, a[j], /Structure
** Structure <17ce540>, 4 tags, length=24, data length=24, refs=2:
INT_1 LONG 1
INT_2 LONG 42
FLOAT_1 FLOAT 3.14000
STR STRING 'Blah'
** Structure <17ce540>, 4 tags, length=24, data length=24, refs=2:
INT_1 LONG 2
INT_2 LONG 77
FLOAT_1 FLOAT 4.13000
STR STRING 'String'
IDL> b = UnpackData(data[1])
IDL> FOR j=0,N_Elements(b)-1 DO Help, b[j], /Structure
** Structure <17ce230>, 4 tags, length=24, data length=24, refs=2:
INT_1 LONG 1
INT_2 LONG 11
FLOAT_1 FLOAT 1.34000
STR STRING 'String'
** Structure <17ce230>, 4 tags, length=24, data length=24, refs=2:
INT_1 LONG 2
INT_2 LONG 22
FLOAT_1 FLOAT 1.43000
STR STRING 'Blah'
** Structure <17ce230>, 4 tags, length=24, data length=24, refs=2:
INT_1 LONG 3
INT_2 LONG 33
FLOAT_1 FLOAT 3.41000
STR STRING 'String'
And so forth. Of course, you can give the structure more useful
names, etc. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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