mlosch/interp_llc/change.m

function new = change(old,relation,flag,value)

% CHANGE     Change values in a matrix
%--------------------------------------------------------------------
% CHANGE   1.3   92/03/25
%
% new = change(old,relation,flag,value)
%
% DESCRIPTION:
%    Changes the 'flag' values in the matrix "old" to the new "value"
%    according to the "relation".
% 
% INPUT:
%    old      = matrix containing values related to "flag"
%               are to be converted to "value"
%    flag     = values related to "flag" then replaced by "value"
%    value    = replacement value
%    relation = string relation e.g. '<', '>', '=='
%
% OUTPUT:
%    new      = matrix "old" with all flagged values changed
%               to "value" (can be returned to same matrix "old")
%
% EXAMPLE:  A = change(A,'==',NaN,0  )
%           B = change(A,'<', -99,NaN) 
%
% CALLER:   general purpose
% CALLEE:   none
%
% AUTHOR:   Phil Morgan 3-02-92

% @(#)change.m   1.3   92/03/25
% @(#)change.m   Martin Losch 02/03/08, 
%                fixed bug that couldn't handle ~= NaN
% 
% Re-created after 2-2-92 hard disk crash.
% Based on flagnan.m - Steve Rintoul  Dec 90
%          alter.m   - Phil  Morgan    Feb 91
%          convert.m - Peter Mcintosh Aug 91
%--------------------------------------------------------------------

% CHECK INPUT ARGUMENTS CALL
if nargin ~= 4
  error('CHANGE.M: Must have 4 input arguments')
end

if (strcmp(relation,'==') | strcmp(relation,'>') | strcmp(relation,'<') | ...
                      strcmp(relation,'~=') | strcmp(relation,'>=') | ...
                      strcmp(relation,'<=')) 
    % valid relation
  else
    error(['CHANGE.M: Relation ''' relation ''' not valid'])
end

% BODY
if isnan(flag)
  if strcmp(relation,'==')
    replace = find(isnan(old));
  elseif strcmp(relation,'~=')
    replace = find(~isnan(old));
  else
    error(['CHANGE.M: Relation ''' relation ''' not valid for flag NaN'])
  end
else
   eval(['replace = find(old',relation,'flag);']);
end
nreplace = length(replace);
new      = old;
if nreplace>0
   new(replace) = value*ones(1,nreplace);
end %if
%--------------------------------------------------------------------


1	function new = change(old,relation,flag,value)
2
3	% CHANGE Change values in a matrix
4	%--------------------------------------------------------------------
5	% CHANGE 1.3 92/03/25
6	%
7	% new = change(old,relation,flag,value)
8	%
9	% DESCRIPTION:
10	% Changes the 'flag' values in the matrix "old" to the new "value"
11	% according to the "relation".
12	%
13	% INPUT:
14	% old = matrix containing values related to "flag"
15	% are to be converted to "value"
16	% flag = values related to "flag" then replaced by "value"
17	% value = replacement value
18	% relation = string relation e.g. '<', '>', '=='
19	%
20	% OUTPUT:
21	% new = matrix "old" with all flagged values changed
22	% to "value" (can be returned to same matrix "old")
23	%
24	% EXAMPLE: A = change(A,'==',NaN,0 )
25	% B = change(A,'<', -99,NaN)
26	%
27	% CALLER: general purpose
28	% CALLEE: none
29	%
30	% AUTHOR: Phil Morgan 3-02-92
31
32	% @(#)change.m 1.3 92/03/25
33	% @(#)change.m Martin Losch 02/03/08,
34	% fixed bug that couldn't handle ~= NaN
35	%
36	% Re-created after 2-2-92 hard disk crash.
37	% Based on flagnan.m - Steve Rintoul Dec 90
38	% alter.m - Phil Morgan Feb 91
39	% convert.m - Peter Mcintosh Aug 91
40	%--------------------------------------------------------------------
41
42	% CHECK INPUT ARGUMENTS CALL
43	if nargin ~= 4
44	error('CHANGE.M: Must have 4 input arguments')
45	end
46
47	if (strcmp(relation,'==') \| strcmp(relation,'>') \| strcmp(relation,'<') \| ...
48	strcmp(relation,'~=') \| strcmp(relation,'>=') \| ...
49	strcmp(relation,'<='))
50	% valid relation
51	else
52	error(['CHANGE.M: Relation ''' relation ''' not valid'])
53	end
54
55	% BODY
56	if isnan(flag)
57	if strcmp(relation,'==')
58	replace = find(isnan(old));
59	elseif strcmp(relation,'~=')
60	replace = find(~isnan(old));
61	else
62	error(['CHANGE.M: Relation ''' relation ''' not valid for flag NaN'])
63	end
64	else
65	eval(['replace = find(old',relation,'flag);']);
66	end
67	nreplace = length(replace);
68	new = old;
69	if nreplace>0
70	new(replace) = value*ones(1,nreplace);
71	end %if
72	%--------------------------------------------------------------------
73
74