Finding category/string in table and converting values

Question

Hao Tang 2018-2-20

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https://ww2.mathworks.cn/matlabcentral/answers/383763-finding-category-string-in-table-and-converting-values

评论： Hao Tang 2018-2-21

Alright so I'm having trouble knowing how to write a script to convert values.

Basically, I want to 1) Read in a file or Access a table 2) Find all the instances in the rows of the table with the string "CBEAM" 3) In said row, go to the 4th column and multiply that number by 0.5 4) Find all instances in the rows of the table with the string "CQUADR" 5) In said row, go to the 6th column and multiply that number by 0.6

So I can envision lots of if, then statements, which is totally fine. But I really don't know how to get started or what to write at all. Can anyone help

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Answer 1

Peter Perkins 2018-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/383763-finding-category-string-in-table-and-converting-values#answer_306343

在 MATLAB Online 中打开

Don't do that. Assume T is your data stored in a table containing a categtorical variable named SomeVarName whose categories are 'CBEAM' 'CQUADR', ... . Then

i = (T.SomeVarName == 'CBEAM');
T.SixthVarName(i) = .5 * T.SixthVarName(i);

etc.

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Hao Tang 2018-2-21

Thanks Steven, this works well! I didn't realize it was that simple. I'll let you know if I have any further questions later.

Hao Tang 2018-2-21

在 MATLAB Online 中打开

Ran into an issue. So I have this 'PBEAM' info on two lines, with commas indicating new columns.

PBEAM,46,1,3.8750077499845,1.251e+00,1.251e+00,,1.001e+01,,+C1
+C1,0.9842519685,0.9842519685,-0.9842519685,0.9842519685,0.9842519685,-0.9842519685,-0.9842519685,-0.9842519685

In matlab, I can find the word 'PBEAM' go to the 4th column and replace the value by multiplying the value with a constant. However, it can't find the next line. EVEN if it did, the constant I multiply with is different, yet falls under the same column as the line above. Not sure how to solve this issue.

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