Use logical indexing to create a new structure containing specific data from an excel file

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Cam B 2022-2-20

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https://ww2.mathworks.cn/matlabcentral/answers/1654275-use-logical-indexing-to-create-a-new-structure-containing-specific-data-from-an-excel-file

评论： Stephen23 2022-2-20

The question asks to create a new structure from a data set for dogs. And do the same for cats. An excel file was given which a multitude of data (101 rows and 15 columns). The columns denoted things such as age, size, name, etc., in which one was designated for "species", which listed either dog or cat. The excel file was converted to a structure with the table2struct function.

file1 = readtable('Random.xlsx'); %use readtable function to load caregiver data

table = table2struct(file1)

How would I go about extracing all the data just for the dogs. No looping.

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Stephen23 2022-2-20

Do NOT call any variable TABLE, because this shadows the inbuilt TABLE function.

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Answer 1

Voss 2022-2-20

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1654275-use-logical-indexing-to-create-a-new-structure-containing-specific-data-from-an-excel-file#answer_900455

在 MATLAB Online 中打开

Random.xlsx

file1 = readtable('Random.xlsx') %use readtable function to load caregiver data 
file1 = 3×5 table
    Age       Size            Name         Species    Is_A_Good_Boy_or_Girl
    ___    __________    ______________    _______    _____________________

     2     {'small' }    {'Fido'      }    {'Dog'}            true         
     4     {'large' }    {'Mr Pickles'}    {'Cat'}            true         
     9     {'medium'}    {'Rex'       }    {'Dog'}            true         
table = table2struct(file1)
table = 3×1 struct array with fields:
    Age
    Size
    Name
    Species
    Is_A_Good_Boy_or_Girl
dog_data = table(strcmp({table.Species},'Dog'))
dog_data = 2×1 struct array with fields:
    Age
    Size
    Name
    Species
    Is_A_Good_Boy_or_Girl
[dog_data.Age]
ans = 1×2
     2     9
{dog_data.Size}
ans = 1×2 cell array
    {'small'}    {'medium'}
{dog_data.Name}
ans = 1×2 cell array
    {'Fido'}    {'Rex'}
[dog_data.Is_A_Good_Boy_or_Girl]
ans = 1×2 logical array
   1   1

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Cam B 2022-2-20

Thank you. Also, how would I go about finding the number of dogs?

Voss 2022-2-20

在 MATLAB Online 中打开

Random.xlsx

You're welcome!

file1 = readtable('Random.xlsx'); %use readtable function to load caregiver data
table = table2struct(file1);
% using the full struct array:
nnz(strcmp({table.Species},'Dog'))
ans = 2
% or, after creating the dog struct array:
dog_data = table(strcmp({table.Species},'Dog'));
numel(dog_data)
ans = 2