Getting rows from dataset with particular value

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Neesha 2014-10-27

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评论： Neesha 2014-10-27

Hi All,

I have a dataset 'Resturants' which has a column with title 'Name'. Now all restaurants name are different but few of them have particular string in prefix like some of them start with 'genName' and followed by something e.g. 'genNameSouthIndian', 'genNameWestLocation'.

So out of my dataset i want to grab all rows which does not have 'genName' prefix. How do i do that?

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Answer 1

Kelly Kearney 2014-10-27

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isgen = ~cellfun('isempty', regexp(restInfo.Name, '^genName'));
restInfo(~isgen,:)
ans = 
      val1    val2    Name            
      1       13      'coolEatery'    
      3        9      'Taj'           
      0        0      'TheVillage'

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Neesha 2014-10-27

What does '^' do before 'genName'? I used 'genName*' but with both i m getting the same results. Hence curious

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Answer 2

Adam 2014-10-27

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I'm not too familiar with the 'dataset' structure if that is what you are using (incidentally Matlab R2014b notes this may be removed in future releases as you should use 'table' instead), but the following:

idx = ~strncmp( str, 'genName', 7 );

will give you the row indices you want if 'str' is your column in question, e.g.

str = Restaurants{:,3};

if it were the 3rd column.

Then you should just be able to use logical indexing with idx to retain only rows that do not have the 'genName' prefix in the chosen column. Again though I'm not familiar if you can do logical indexing on rows of a dataset object, but I would have thought you can.

e.g.

myRestaurants = Restaurants{ :, idx };

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Adam 2014-10-27

That may not be correct syntax for a dataset (if that is the structure you are using), but I'm really not familiar with them enough to give a better guess at the moment. Maybe someone else can help with that last part.

Does the code prior to it work though to give you the indices to the correct rows?

Neesha 2014-10-27

Yes prior work gives right indices. I have accepted kelly's answer since that worked for me. Thanks

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Answer 3

Neesha 2014-10-27

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https://ww2.mathworks.cn/matlabcentral/answers/160293-getting-rows-from-dataset-with-particular-value#answer_156761

在 MATLAB Online 中打开

so here is my code, can you help me out please:

 restInfo = dataset();
 restInfo.val1 = 1;
 restInfo.val1(2, 1) = 1;
 restInfo.val1(3, 1) = 2;
 restInfo.val1(4, 1) = 3;
 restInfo.val1(5, 1) = 0;
 restInfo.val2 = 11;
 restInfo.val2(2, 1) = 13;
 restInfo.val2(3, 1) = 0;
 restInfo.val2(4, 1) = 9;
 restInfo.val2(5, 1) = 0;
 restInfo.Name = {'genNameSouthLocation'};
 restInfo.Name(2, 1) = {'coolEatery'};
 restInfo.Name(3, 1) = {'genNameMexican'};
 restInfo.Name(4, 1) = {'Taj'};
 restInfo.Name(5, 1) = {'TheVillage'};