| Checking datatypes (datatype.pro) [message #4751] |
Thu, 13 July 1995 00:00 |
Russ Welti
Messages: 27
Registered: October 1994
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Junior Member |
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Someone posted about the danger of IDL variables and
parameters being of unexpected datatypes. There is
a little function, 'datatype' (probably based on HELP)
which is handy for verifying that the type is what
you expect it is at critical times, such as upon
entering a routine.
For example:
IDL> j=1L
IDL> if datatype(j) NE 'LON' then message,'Invalid datatype for j.'
IDL>
IDL> j=1.0
IDL> if datatype(j) NE 'LON' then message,'Invalid datatype for j.'
% $MAIN$: Invalid datatype for j.
I find it very helpful.
Thank you, Ray Sterner, and here it is:
;----------------------------------------------------------- --
;+
; NAME:
; DATATYPE
; PURPOSE:
; Datatype of variable as a string (3 char or spelled out).
; CATEGORY:
; CALLING SEQUENCE:
; typ = datatype(var, [flag])
; INPUTS:
; var = variable to examine. in
; flag = output format flag (def=0). in
; KEYWORD PARAMETERS:
; Keywords:
; /DESCRIPTOR returns a descriptor for the given variable.
; If the variable is a scalar the value is returned as
; a string. If it is an array a description is return
; just like the HELP command gives. Ex:
; datatype(fltarr(2,3,5),/desc) gives
; FLTARR(2,3,5) (flag always defaults to 3 for /DESC).
; OUTPUTS:
; typ = datatype string or number. out
; flag=0 flag=1 flag=2 flag=3
; UND Undefined 0 UND
; BYT Byte 1 BYT
; INT Integer 2 INT
; LON Long 3 LON
; FLO Float 4 FLT
; DOU Double 5 DBL
; COM Complex 6 COMPLEX
; STR String 7 STR
; STC Structure 8 STC
; COMMON BLOCKS:
; NOTES:
; MODIFICATION HISTORY:
; Written by R. Sterner, 24 Oct, 1985.
; RES 29 June, 1988 --- added spelled out TYPE.
; R. Sterner, 13 Dec 1990 --- Added strings and structures.
; R. Sterner, 19 Jun, 1991 --- Added format 3.
; R. Sterner, 18 Mar, 1993 --- Added /DESCRIPTOR.
; Johns Hopkins University Applied Physics Laboratory.
;
; Copyright (C) 1985, Johns Hopkins University/Applied Physics Laboratory
; This software may be used, copied, or redistributed as long as it is not
; sold and this copyright notice is reproduced on each copy made. This
; routine is provided as is without any express or implied warranties
; whatsoever. Other limitations apply as described in the file disclaimer.txt.
;-
;----------------------------------------------------------- --
function datatype,var, flag0, descriptor=desc, help=hlp
if (n_params(0) lt 1) or keyword_set(hlp) then begin
print,' Datatype of variable as a string (3 char or spelled out).'
print,' typ = datatype(var, [flag])'
print,' var = variable to examine. in'
print,' flag = output format flag (def=0). in'
print,' typ = datatype string or number. out'
print,' flag=0 flag=1 flag=2 flag=3'
print,' UND Undefined 0 UND'
print,' BYT Byte 1 BYT'
print,' INT Integer 2 INT'
print,' LON Long 3 LON'
print,' FLO Float 4 FLT'
print,' DOU Double 5 DBL'
print,' COM Complex 6 COMPLEX'
print,' STR String 7 STR'
print,' STC Structure 8 STC'
print,' Keywords:'
print,' /DESCRIPTOR returns a descriptor for the given variable.'
print,' If the variable is a scalar the value is returned as'
print,' a string. If it is an array a description is return'
print,' just like the HELP command gives. Ex:'
print,' datatype(fltarr(2,3,5),/desc) gives'
print,' FLTARR(2,3,5) (flag always defaults to 3 for /DESC).'
return, -1
endif
if n_params(0) lt 2 then flag0 = 0 ; Default flag.
flag = flag0 ; Make a copy.
if n_elements(var) eq 0 then begin
s = [0,0]
endif else begin
s = size(var)
endelse
if keyword_set(desc) then flag = 3
if flag eq 2 then typ = s(s(0)+1)
if flag eq 0 then begin
case s(s(0)+1) of
0: typ = 'UND'
7: typ = 'STR'
1: typ = 'BYT'
2: typ = 'INT'
4: typ = 'FLO'
3: typ = 'LON'
5: typ = 'DOU'
6: typ = 'COM'
7: typ = 'STR'
8: typ = 'STC'
else: print,'Error in datatype'
endcase
endif else if flag eq 1 then begin
case s(s(0)+1) of
0: typ = 'Undefined'
7: typ = 'String'
1: typ = 'Byte'
2: typ = 'Integer'
4: typ = 'Float'
3: typ = 'Long'
5: typ = 'Double'
6: typ = 'Complex'
7: typ = 'String'
8: typ = 'Structure'
else: print,'Error in datatype'
endcase
endif else if flag eq 3 then begin
case s(s(0)+1) of
0: typ = 'UND'
7: typ = 'STR'
1: typ = 'BYT'
2: typ = 'INT'
4: typ = 'FLT'
3: typ = 'LON'
5: typ = 'DBL'
6: typ = 'COMPLEX'
7: typ = 'STR'
8: typ = 'STC'
else: print,'Error in datatype'
endcase
endif
if not keyword_set(desc) then begin
return, typ ; Return data type.
endif else begin
if s(0) eq 0 then return,strtrim(var,2) ; Return scalar desc.
aa = typ+'ARR('
for i = 1, s(0) do begin
aa = aa + strtrim(s(i),2)
if i lt s(0) then aa = aa + ','
endfor
aa = aa+')'
return, aa
endelse
end
/
Russ Welti /-\
(c-g)
University of Washington \-/
Molecular Biotechnology /
PO Box 352145 /-\
Seattle, WA 98195 (a-t)
rwelti@u.washington.edu \-/
(206) 685 3840 voice (206) 685 7344 FAX /
http://chroma.mbt.washington.edu/graphics/gif/russ.gif
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