Dealing with strings and numbers in a for loop.

Question

Ashfaq Ahmed 2022-3-22

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1677894-dealing-with-strings-and-numbers-in-a-for-loop

编辑： Stephen23 2022-3-22

采纳的回答： Steven Lord

在 MATLAB Online 中打开

Hi guys,

I have

April2003 = 55;
April2004 = 279;
April2005 = 311;
.
.
.
.
April20020 = 119

How can I run a for loop that sums up all these data for me? I tried this, but it doesn't work -

for i = 2003:2020
    APRIL_total = sum('April',num2str(i))
end

Can anyone please help me?

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Stephen23 2022-3-22

编辑：Stephen23 2022-3-22

在 MATLAB Online 中打开

"I have..." badly designed data that forces me into writing slow, complex, inefficient code when I try to access it in a loop.

The cause is forcing meta-data into the variable names.

"Can anyone please help me?"

You can help you, by not forcing meta-data into variable names. Use arrays, just like MATLAB is designed for, to store both your data (number values) and your meta-data (dates).

A TIMETABLE might be agood choice for your data:

DT = datetime([2003;2003;2004;2005;2020;2020],[1;4;4;4;1;4],1);
V =  [23;55;279;311;64;119];
TT = timetable(DT,V)
TT = 6×1 timetable
        DT          V 
    ___________    ___

    01-Jan-2003     23
    01-Apr-2003     55
    01-Apr-2004    279
    01-Apr-2005    311
    01-Jan-2020     64
    01-Apr-2020    119
Z = groupsummary(TT,'DT','monthofyear','sum')
Z = 2×3 table
    monthofyear_DT    GroupCount    sum_V
    ______________    __________    _____

          1               2           87 
          4               4          764 

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Answer 1

Steven Lord 2022-3-22

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1677894-dealing-with-strings-and-numbers-in-a-for-loop#answer_924284

Having variables with numbered names like this is a code smell. See this Answers post for an explanation of why they smell and alternatives you should use instead.