change table var type

How can I change the variable type in a table from double to string ?

I found plenty of posts with the same issue but during import from excel. My table is already there and I need to change the var type of a column.

[KSSV]

Read about num2str, sprintf.

[LO]

I resolved by creating a new 1column table of the right type and then concatenating it to the existing table (ugly but it works)

Answer 1

[Steven Lord]

A = array2table(magic(4))

A = 4x4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

     16       2       3      13 
      5      11      10       8 
      9       7       6      12 
      4      14      15       1 

A.Var1 = string(A.Var1)

A = 4x4 table
    Var1    Var2    Var3    Var4
    ____    ____    ____    ____

    "16"      2       3      13 
    "5"      11      10       8 
    "9"       7       6      12 
    "4"      14      15       1 

Though depending what you're trying to do, using discretize or categorical to create a categorical array might be a better option.

load patients
patients = table(LastName,Gender,Age,Height,Weight);
head(patients)

ans = 8x5 table
      LastName        Gender      Age    Height    Weight
    ____________    __________    ___    ______    ______

    {'Smith'   }    {'Male'  }    38       71       176  
    {'Johnson' }    {'Male'  }    43       69       163  
    {'Williams'}    {'Female'}    38       64       131  
    {'Jones'   }    {'Female'}    40       67       133  
    {'Brown'   }    {'Female'}    49       64       119  
    {'Davis'   }    {'Female'}    46       68       142  
    {'Miller'  }    {'Female'}    33       64       142  
    {'Wilson'  }    {'Male'  }    40       68       180  

patients.AgeCategory = discretize(patients.Age, 0:10:100, 'categorical');
patients.Gender = categorical(patients.Gender);
head(patients)

ans = 8x6 table
      LastName      Gender    Age    Height    Weight    AgeCategory
    ____________    ______    ___    ______    ______    ___________

    {'Smith'   }    Male      38       71       176       [30, 40)  
    {'Johnson' }    Male      43       69       163       [40, 50)  
    {'Williams'}    Female    38       64       131       [30, 40)  
    {'Jones'   }    Female    40       67       133       [40, 50)  
    {'Brown'   }    Female    49       64       119       [40, 50)  
    {'Davis'   }    Female    46       68       142       [40, 50)  
    {'Miller'  }    Female    33       64       142       [30, 40)  
    {'Wilson'  }    Male      40       68       180       [40, 50)  

Answer 2

[KALYAN ACHARJYA]

"My table is already there and I need to change the var type of a column."

If the data is numeric, you can use num2str(variable_name) to convert numeric var to string data type.

Lets suppose you have table variable T and want to convert string of the particular column variable "col1", then

num2str(T.col1)

[LO]

Thanks Kalyan, I am trying to input strings in a table column in a for loop cycle.

So the inputs are actually strings not numbers. when I try to put the strings into the table variable I just get NaNs (because the column type is double instead of string)

[Jeremy Hughes]

I think you should share your code. Hard to tell what you really need to do.