Replacing a cell value in a struct

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deejt
deejt 2021-1-19
编辑： Image Analyst 2021-1-20
Hello,
I have a struct with 4 fields.
One field contains my conditions (3 conditions, named using strings)
Now I want to replace the strings with numbers. How is that possible? So far I could not find anything :( Is this even possible?
Help is much appreciated!

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采纳的回答

Image Analyst
Image Analyst 2021-1-19
This works:
% Identify what number should replace what character vector.
replacements = {'condi1', 1; 'condi2', 2; 'condi3', 3}
% Make cell array for Conditions
caConditions = {'condi1' 'condi2' 'condi3' 'condi3' 'condi1' 'condi3' 'condi2'}
% Create the whole structure array.
s = struct('subjectnumber', {1 1 1 1 1 1 1}, ...
'condition', caConditions, ...
'rt',{0.12 0.11 0.8 0.9 0.13 0.6 0.12}, ...
'point',{0 40 40 40 20 20 0})
for k = 1 : numel(s)
thisCondition = {s(k).condition}; % Character vector like 'condi1', or 'condi2', etc.
% Compare this condition to the list of them in column 1 of replacements
% and find out which row contains the replacement.
[~, row] = ismember(thisCondition, replacements(:, 1));
% Replace it with the number in column 2
s(k).condition = replacements{row, 2};
end
  2 个评论
deejt
deejt 2021-1-19
编辑：deejt 2021-1-19
Thank you so much! This indeed solved my problem!!!
How would I proceed, if I had so many more entries (because 7 is very easy).
But at this part for example: what if I had 24778 entries - I can't possibly type in everything manually can I?
s = struct('subjectnumber', {1 1 1 1 1 1 1}, ...
'condition', caConditions, ...
'rt',{0.12 0.11 0.8 0.9 0.13 0.6 0.12}, ...
'point',{0 40 40 40 20 20 0})
Image Analyst
Image Analyst 2021-1-20
编辑：Image Analyst 2021-1-20
Are you saying that you could have 25 thousand different strings? If so, rather than a look up table like I used, you'd need to use something like sscanf() to parse/extract the number out of the character string.

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更多回答（2 个）

Image Analyst
Image Analyst 2021-1-19
Yes. For example to set the "condition" field to the number 5, do this:
yourStruct.condition = 5;
It doesn't matter that it used to be a string.
Attach your structure in a .mat file, or give code to create it, if you still have problems.
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Image Analyst
Image Analyst 2021-1-19
AGAIN:
Attach your structure in a .mat file, or give code to create it, if you still have problems.
I need it because I'm not sure how condition is what you showed : 3 character arrays. It can be a character matrix, a string vector, or even a cell array, but I don't know what you have or how you displayed that. Plus answer Bob's questions.
deejt
deejt 2021-1-19
编辑：deejt 2021-1-19
@Image Analyst when I tried your suggestion I received an error msg unfortunately. I attached it here, maybe I am overseeing something! (I am new to programming and just trying to figure out some basics).
"Scalar structure required for this
assignment.
Error in TutorialSession (line 4)
s.condition = 5"

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deejt
deejt 2021-1-19
编辑：deejt 2021-1-19
Thank you guys for the effort.
@Bob Thompson Yes, I am trying to do a search/find and replace. In every cell of the field block I want to change the name that is in string to a numerical value.
condi1 should become 1, condi2 should become 2, condi3 should become 3 in every cell these string appear.
Thank you!

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