if else, for loop, working with character variables

Question

Binzi Shu 2016-3-2

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/271082-if-else-for-loop-working-with-character-variables

评论： Kirby Fears 2016-3-4

采纳的回答： Kirby Fears

z = Data(1:10,17) %take 10 numerical values into a new table, name of the variable is LOAN

for i = 1:height(z)

if z.LOAN(i)>300000

z.new(i) = 'pass'

else z.new(i) = 'fail'

end

So the above is giving me an error: In an assignment A(:) = B, the number of elements in A and B must be the same.

But if I change the above code to the following:

z = Data(1:10,17) %take 10 numerical values into a new table

for i = 1:height(z)

if z.LOAN(i)>300000

z.new(i) = 1

else z.new(i) = 0

end

Then the codes work fine. Why is it only working if I put 1/0 rather than pass/fail? How can I solve this? Thanks.

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Answer 1

Kirby Fears 2016-3-2

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https://ww2.mathworks.cn/matlabcentral/answers/271082-if-else-for-loop-working-with-character-variables#answer_212045

在 MATLAB Online 中打开

Two questions:

1. Is z.new initialized before you start assigning values to it?

2. Did you try curly braces?

if z.LOAN(i)>300000,
    z.new{i} = 'pass';
else
    z.new{i} = 'fail';
end

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Binzi Shu 2016-3-2

yes it worked! Thanks! Could you brief talk about the difference btw {} and ()? Thanks again.

Kirby Fears 2016-3-4

在 MATLAB Online 中打开

Each variable in your table can be a numeric array or a cell array. For example, your LOAN variable is a numeric array.

When indexing a numeric array for value access or assignment, parentheses are used. However, curly braces are used to access or assign values in a cell array like z.new.

The difference is that a cell array contains cells while a double array contains the primitive double type. Parentheses work in a double array because you are assigning a double to a particular position in the array.

Parentheses work as well for cell arrays as long as you assign a cell to the indexed position.

For example:

z.new(1) = {'pass'}

But you cannot assign the character array 'pass' directly into the cell array because 'pass' is not a cell. Curly braces can be used to access or assign contents of a cell in the array:

z.new{1} = 'pass'

Hope this helps.

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