Assigning a single value to cell array with logical indexing.

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Hi All,
I am wondering if the code I have below is optimal for what it does, or if there are better ways to do this.
VDIV{1} = [2 5 7 10 13 13.2 20 30 50 100 200 500 1000]*1E-3;
VDIV{2} = [VDIV{1} 5 10];
numVDIVs = numel(VDIV{2});
AmpLimitField = cell(numVDIVs,1);
[AmpLimitField{VDIV{2} < 102E-3}] = deal('X1');
[AmpLimitField{VDIV{2} >= 1.02}] = deal('X100');
% When VDIV{2} >= 102E-3 && VDIV{2} < 1.02}
[AmpLimitField{cellfun(@isempty,AmpLimitField)}] = deal('X10');
Outputs:
AmpLimitField =
'X1'
'X1'
'X1'
'X1'
'X1'
'X1'
'X1'
'X1'
'X1'
'X1'
'X10'
'X10'
'X10'
'X100'
'X100'

Accepted Answer

per isakson
per isakson on 11 May 2013
Edited: per isakson on 11 May 2013
"... for what it does ..."
  • it creates a cell array of strings, AmpLimitField
  • it takes a cell array, VDIV, as input
However, I see no reason why not use an array of double in place of VDIV. Thus, I have replaced VDIV{2} by vdv.
Your assignment
[AmpLimitField{cellfun(@isempty,AmpLimitField)}] = deal('X10');
is questionable, since it may hide mistakes in the logic. Whether or not all the greater and lesser than are correct a string will be assigned to AmpLimitField. It is better that a mistake show up as an empty cell.
One more comment
CellArray( condition ) = { string };
is easier to read and a bit faster than
[ CellArray{ condition } ] = deal( string );
.
Try
>> cssm
Elapsed time is 0.000082 seconds.
Elapsed time is 0.000228 seconds.
Equal!
>>
where
function cssm()
tic
alf1 = cssm_();
toc
tic
alf2 = op();
toc
if all( cellfun( @(s1,s2) all(eq(s1,s2)), alf1, alf2 ) )
disp( 'Equal!' )
else
disp( 'Not equal!' )
end
end
function alf = cssm_()
vdv = [ [2,5,7,10,13,13.2,20,30,50,100,200,500,1000]*1E-3, 5, 10 ];
len = numel( vdv );
alf = cell( len, 1 );
alf( vdv < 0.102 ) = {'X1'};
alf( vdv >= 0.102 & vdv < 1.02 ) = {'X10'};
alf( vdv >= 1.02 ) = {'X100'};
end
function AmpLimitField = op()
VDIV{1} = [2 5 7 10 13 13.2 20 30 50 100 200 500 1000]*1E-3;
VDIV{2} = [VDIV{1} 5 10];
numVDIVs = numel(VDIV{2});
AmpLimitField = cell(numVDIVs,1);
[AmpLimitField{VDIV{2} < 102E-3}] = deal('X1');
[AmpLimitField{VDIV{2} >= 1.02}] = deal('X100');
% When VDIV{2} >= 102E-3 && VDIV{2} < 1.02}
[AmpLimitField{cellfun(@isempty,AmpLimitField)}] = deal('X10');
end
  1 Comment
Leor Greenberger
Leor Greenberger on 13 May 2013
Edited: Leor Greenberger on 13 May 2013
Thank you very much, per!
I am always looking to learn how to improve my matlab code. On a side note, the reason why VDIV is a cell array is because I am using it in a for loop where in the outer loop, I am iterating on the cell array. I excluded this code from my question to simplify things. The loops are required because I am controlling external instruments and the code must run sequentially through each VDIV element.
VDIV{1} = [2 5 7 10 13 13.2 20 30 50 100 200 500 1000]*1E-3;
VDIV{2} = [VDIV{1} 5 10];
...
for i = 1:2
...
for x = VDIV{i}
...
end
end

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