Changing the For LOOP conditions

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Jason
Jason 2019-10-10
评论： Jason 2019-10-10
Hello.
I have a for loop that starts with image number 1 and ends with the last image n.
for i=1:n
Sometimes, I only need to analyse every other image- starting at image 2, so would require
for i=2:2:n
I would like to use a checkbox to determine the parameters of the loop.
Rather than write out 2 different loops depending on the value of a checkbox, is there a way where i can just use a single for loop with some condition at the start
i.e.
val=get(handles.checkbox1,'Value)
if val==1
use i=1:n
else
use i=2:2:n
end

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采纳的回答

Shubham Gupta
Shubham Gupta 2019-10-10
编辑：Shubham Gupta 2019-10-10
One of the way to do this is define the for loop conditions using predefined vectors.
You can write vector to set how the for loop varies. For e.g.
Vec = 1:10
for i = Vec
printf('%d',i)
end
Now, you just need to set Vec according the checkbox :
val=get(handles.checkbox1,'Value')
Vec1 = 1:n;
Vec2 = 2:2:n;
if val==1
Vec = Vec1;
else
Vec = Vec2;
end
for i = Vec
% operation
end

更多回答（1 个）

Stephen23
Stephen23 2019-10-10
编辑：Stephen23 2019-10-10
If val has a value either 1 or 2:
for k = 1:val:n
If val is a boolean (i.e. 0 or 1) then simply do either of these:
for k = 1:(1+val):n % true->2, false->1
for k = 1:(2-val):n % true->1, false->2
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Stephen23
Stephen23 2019-10-10
编辑：Stephen23 2019-10-10
"But also the starting value needs to be 1 or 2."
That is such a trivially simple change, that I sure that you could have figured that out yourself:
for k = val:val:n
And for the boolean you can also do it quite simply. Using if is a waste of MATLAB, when you can simply set the step size directly. Using intermediate vectors is also pointless.
Jason
Jason 2019-10-10
Ok, i will use this approach. Thanks

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