Read in matrix for multiple steps while changing string

Question

Alexandra Vest 2023-5-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1972359-read-in-matrix-for-multiple-steps-while-changing-string

评论： Steven Lord 2023-5-24

采纳的回答： Steven Lord

Hi, I want to read in multiple temperature files at different time steps. For instance I have array:

time = [0, 10, 20];

And I need to read in:

temp0 = "temperature_0.txt"

temp1 = "temperature_10.txt"

temp2 = "temperature_20.txt"

So I can compile them all into:

temp = [temp0;temp1;temp2]

How can I handle changing the string names "temp0" and "temperature_0.txt" based on the value in time? I know I will have a for loop such as follows, but I am unsure of how to make the variable input into the name as a string

for k = 1:length(time)

...

end

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Stephen23 2023-5-24

编辑：Stephen23 2023-5-24

https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

From what you explain in the comment, probably DIR is the easiest approach.

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Answer 1

Steven Lord 2023-5-24

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https://ww2.mathworks.cn/matlabcentral/answers/1972359-read-in-matrix-for-multiple-steps-while-changing-string#answer_1243749

在 MATLAB Online 中打开

time = [0, 10, 20];
files = "temperature_" + time + ".txt"
files = 1×3 string array
    "temperature_0.txt"    "temperature_10.txt"    "temperature_20.txt"

Now you could iterate over the elements of the files string array.

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Alexandra Vest 2023-5-24

A follow-up question, if I have a bunch of file, let's say "log_0.txt", "log_10.txt" "log_20.txt" and I wanted to read in the numbers on the latter end of the file name to create the array time=[0,10,20] is there a way to do that? I don't need to read in those files, just take the number following log_. Thank you!

Steven Lord 2023-5-24

在 MATLAB Online 中打开

If the only digits in the names are in the numbers you want to extract, use digitsPattern to extract that data from the string array.

time = [0, 10, 20];
files = "temperature_" + time + ".txt"
files = 1×3 string array
    "temperature_0.txt"    "temperature_10.txt"    "temperature_20.txt"
numbersAsText = extract(files, digitsPattern)
numbersAsText = 1×3 string array
    "0"    "10"    "20"
numbers = double(numbersAsText)
numbers = 1×3
     0    10    20
isequal(time, numbers)
ans = logical
   1