I don't know that it is more elegant but it is built into solarsoft as
rem_tag.pro
[larsen@titan]~> cat /usr/local/ssw/gen/idl/struct/rem_tag.pro
;+
; Project : HESSI
;
; Name : REM_TAG
;
; Purpose : remove tags from a structure
;
; Syntax : NEW_STRUCT=REM_TAG(STRUCT,TAG)
;
; Inputs : STRUCT = input structure (array or scalar)
; : TAG = array of tag names or indexes to remove
;
; Outputs : NEW_STRUCT = new structure
;
; Keywords : NAME = new name for structure (use with care)
;
; Category : Structure handling
;
; Written : 1-Dec-02, Zarro (EER/GSFC)
;
; Modified : 24-Dec-04, Zarro (L-3Com/GSFC)
; - vectorized, and removed dangerous /free_mem
; 01-Feb-05, Csillaghy (Univ. Applied Sciences NW
Switzerland)
; - changed n_elements( struct ) to size(struct /dim ),
see at the end.
;-
function
rem_tag,struct,tags,_extra=extra,quiet=quiet,err=err,name=na me
verbose=1-keyword_set(quiet)
;-- bypass for older IDL versions
forward_function rem_tag2
if (1-since_version('5.4')) then begin
if have_proc('rem_tag2') then $
return,rem_tag2(struct,tags,_extra=extra,name=name,err=err)
message,'no longer supported for this version of IDL - '+!
version.release,/cont
if exist(struct) then return,struct else return,-1
endif
;-- catch errors
err=''
error=0
catch,error
if error ne 0 then begin
err=err_state()
if verbose then message,err,/cont
catch,/cancel
if exist(struct) then return,struct else return,-1
endif
if (1-is_struct(struct)) then begin
err='invalid input'
pr_syntax,'new_struct=rem_tag(struct,tag_name)'
if exist(struct) then return,struct else return,-1
endif
sz=size(tags,/type)
index_input=(sz gt 1) and (sz lt 6)
string_input=(sz eq 7)
err='input tag names or tag indexes required'
if (not index_input) and (not string_input) then begin
if verbose then message,err,/cont & return,struct
endif
if string_input and is_blank(tags) then begin
if verbose then message,err,/cont & return,struct
endif
;-- create structure template with tags removed
err=''
stag_names=tag_names(struct)
ntags=n_elements(stag_names) & stag_index=lindgen(ntags)
for i=0,ntags-1 do begin
if string_input then chk=where(strup(tags) eq stag_names[i],count)
else $
chk=where(long(tags) eq stag_index[i],count)
if count eq 0 then begin
if is_struct(temp) then $
temp=create_struct(temp,stag_names[i],struct[0].(i)) else $
temp=create_struct(stag_names[i],struct[0].(i))
endif
endfor
;-- all tags removed
if not is_struct(temp) then return,-1
;-- no tags removed
rtags=tag_names(temp)
if n_elements(rtags) eq ntags then return,struct
;-- rename if requested
if is_string(name) then temp=create_struct(temp,name=strup(name))
dims_arr =size(struct, /dim)
if total(dims_arr) GT 1 then $
temp=replicate2(temporary(temp),dims_arr)
struct_assign,struct,temp,/nozero
return,temp
end
Brian
------------------------------------------------------------ ---------
Brian A. Larsen
Dept. of Physics
Space Science and Engineering Lab (SSEL)
Montana State University - Bozeman
Bozeman, MT 59717
On Feb 1, 10:27 am, "M. Katz" <MKatz...@yahoo.com> wrote:
> I was wondering if there's a simple way to remove a field from a
> structure?
>
> I can envision a manual way:
> 0) creating a new structure variable for the result
> 1) reading the original's tag names
> 2) stepping through tag by tag using indexed value references, like a.
> (i)
> 3) using create_struct() to put the tags and values into the new
> structure, one by one, except for the tag(s) we're removing.
>
> Does anyone have a more elegant suggestion?
> M. Katz
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