MATLAB: Change table variable data type

MATLABtable

I used readtable() to read a text file into a table. One of the columns of the table was read (by default) as a double rather than a string. How does one change a columns datatype within a table?

Best Answer

Change it before reading it in by modifying the options passed to readtable.

https://www.mathworks.com/help/releases/R2017a/matlab/ref/detectimportoptions.html

t.Var1 = num2str(t.Var1)

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

You are close, but you are trying to assign a character vector to a double variable (NaN = not a number). You can see that if you run the command summary(mytable).

You also do not need to put the text into a cell if you use the string data type.

See if you can get this code to work for your needs.

myArray = nan(5,2)
mytable = array2table(myArray);
mytable.Properties.VariableNames = {'colA', 'colB'};
mytable2 = convertvars(mytable,"colB",'string');
mytable2.colA(:) = 459;
mytable2.colB(:) = "words"

You say you have a lot of data. If the variables already exist, you could do something like this:

colA = nan(5,1);
colB = strings(5,1);
mytable = table(colA,colB);
mytable.colA(:) = 459; % just a random number, proof-of-concept that it works
mytable.colB(:) = "words" % this throws errors

MATLAB: How to Use a Custom Class with the Same Name as a built-in MATLAB Class

Due to how MATLAB loads classes, this is not possible.

A workaround is to rename the custom class.

To update old MAT files which contain instances of the custom class (before MATLAB introduced the built-in class), see the attached function file "MATconvert.m" as an example of a conversion function. Then follow the steps below:

1. Using a version of MATLAB before the built-in class was introduced:

2. Create the renamed custom class (newClass), and have both versions of the custom class available (oldClass and newClass)

3. Modify the conversion function to dig through your data structures to replace any instances of oldClass with the newClass

4. Run the conversion function on all old MAT files

Best Answer

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

MATLAB: How to Use a Custom Class with the Same Name as a built-in MATLAB Class

Related Question