how can I write a function

i have a data base with name gender and age not necessarily in the same order, some data base is gender name age. for example

'name' 'gender' 'age'

'mary' 'f' 25

'john' 'm' 35

'anna' 'f' 30

'paul' 'm' 22

'elaina' 'f' 38

if i have to use this database as cell array and only get the names of male how i do so?

Answer 1

[Dave B]

Your data look similar to this (as you've described them):

load patients
data=[{'name'} {'gender'} {'age'}; LastName Gender num2cell(Age)]

You just use strcmp to compare strings, and specify you want the rows where gender contains 'm' and column 1

data(strcmp(data(:,2),'Male'),1) % obviously you'll use 'm' in your case

ans = 47×1 cell array
    {'Smith'    }
    {'Johnson'  }
    {'Wilson'   }
    {'Moore'    }
    {'Jackson'  }
    {'White'    }
    {'Martin'   }
    {'Thompson' }
    {'Martinez' }
    {'Robinson' }
    {'Hall'     }
    {'Hernandez'}
    {'King'     }
    {'Scott'    }
    {'Green'    }
    {'Baker'    }
    {'Nelson'   }
    {'Mitchell' }
    {'Perez'    }
    {'Roberts'  }
    {'Turner'   }
    {'Phillips' }
    {'Parker'   }
    {'Edwards'  }
    {'Collins'  }
    {'Stewart'  }
    {'Reed'     }
    {'Bell'     }
    {'Murphy'   }
    {'Ward'     }

If it were me, I'd put these in a table and use strings, it's so much better!

t=array2table(data(2:end,:),'VariableNames',data(1,:));
t.name=string(t.name);
t.gender=categorical(t.gender);
t.age=cell2mat(t.age);
t.name(t.gender=="Male")

ans = 47×1 string array
    "Smith"
    "Johnson"
    "Wilson"
    "Moore"
    "Jackson"
    "White"
    "Martin"
    "Thompson"
    "Martinez"
    "Robinson"
    "Hall"
    "Hernandez"
    "King"
    "Scott"
    "Green"
    "Baker"
    "Nelson"
    "Mitchell"
    "Perez"
    "Roberts"
    "Turner"
    "Phillips"
    "Parker"
    "Edwards"
    "Collins"
    "Stewart"
    "Reed"
    "Bell"
    "Murphy"
    "Ward"

[Manav Divekar]

I can use first option but if the postion of gender is changed in certain database. like

'gender''name' 'age'

'f' 'mary' 25

'm' 'john' 35

'f' 'anna' 30

'm' 'paul' 22

'f' 'elaina' 38

using data(:,2) can not be used. how can i generlize that?

[Manav Divekar]

if i have to use this for a certain age like between 30 and 40

this what i have done so far

function [patient] = filterpatients_cell(data)

patient = data(strcmp(data(:,2),'f'),1) && data(strcmp(data(:,3),'age'=< 30 && 'age' >=40),1);

[Dave B]

Re how to generalize, this is why using a table makes more sense, because then you can refer to a variable name instead of a number. However you could look at the first row with the same principal

load patients
data=[{'name'} {'gender'} {'age'}; LastName Gender num2cell(Age)];
col = strcmp(data(1,:),'gender');
data(strcmp(data(:,col),'Male'),1) 

ans = 47×1 cell array
    {'Smith'    }
    {'Johnson'  }
    {'Wilson'   }
    {'Moore'    }
    {'Jackson'  }
    {'White'    }
    {'Martin'   }
    {'Thompson' }
    {'Martinez' }
    {'Robinson' }
    {'Hall'     }
    {'Hernandez'}
    {'King'     }
    {'Scott'    }
    {'Green'    }
    {'Baker'    }
    {'Nelson'   }
    {'Mitchell' }
    {'Perez'    }
    {'Roberts'  }
    {'Turner'   }
    {'Phillips' }
    {'Parker'   }
    {'Edwards'  }
    {'Collins'  }
    {'Stewart'  }
    {'Reed'     }
    {'Bell'     }
    {'Murphy'   }
    {'Ward'     }

Re how to apply to age

• this approach won't work, 'age' can't be compared to 30.
• strcmp just compares strings, it's not useful for numbers.
• =< is not a matlab operation
• If age a cell, you'll have to convert it to a matrix, and then it'll be off by one row because of the headings.
• Really just use a table, your life will be much easier!

[Manav Divekar]

with this code im getting an emply cell.

[Dave B]

Sorry i've updated the code, and added a demo (but really my intent ws to give you a strategy you can use rather than to write the code for you).