Table with multiple types

I'm trying to use a ui table of 2 columns, one of chars, and the other uint32. Seems like it used to work. Now it fails badly and the workaround to make PType a string is not what I want (makes table of strings). Why can't a table have multipe types as assigned?

Example 1 Try in Command window

PType =

'R'

K>> PData

PData =

uint32

391

Start with

app.LicksTable.Data = [];

Too late ML already decided what the columns are to be (strings in this case)

K>> app.LicksTable.Data = [PType,PData];

Error setting property 'Data' of class 'Table':

Data must be a numeric, logical, string, cell, or table array

Example 3 What happens in my code when I've done PType = convertCharsToStrings(char(PType));

if isempty(app.LicksTable.Data) % Init (sets the var types too)
            app.LicksTable.Data = [PType, PData];
        else    
            app.LicksTable.Data(end+1,:) = [PType, PData];
        end

K>> app.LicksTable.Data

ans =

1×2 string array

"R" "391"

When I tried making it all numeric, then I lose the data (PData still uint32)

K>> PType = uint8(char(PType))

PType =

uint8

76

K>> app.LicksTable.Data = [PType, PData];

K>> app.LicksTable.Data

ans =

1×2 uint8 row vector

76 255

More things to try: (PType a char again)

>> app.LicksTable.Data = table (PType,PData);

Error using table (line 87)

Invalid parameter name: L.

Caused by:

You might have intended to create a one-row table with the character vector 'L' as one of its variables. To store text data in a table, use a string array or a cell array of character vectors rather than character arrays. Alternatively, create a cell array with one row, and convert that to a table using CELL2TABLE.

Well at least that's helpful

K>> PType = convertCharsToStrings(char(PType));

K>> app.LicksTable.Data = [];

K>> app.LicksTable.Data = table (PType,PData);

K>> app.LicksTable.Data

ans =

1×2 table

PType PData

_____ _____

"L" 372

Wow I got it!

For a language that claims to be weakly typed it sure knows how to make a mess!

I'm going to post this anyway in case anyone else is having similar trouble with chars and strings in tables with numbers.

Answer 1

[Matt J]

I guess I might be missing something. Why isn't this what you want?

PType='R';
PData=uint32(391);

fig = uifigure;
uit = uitable(fig,"Data",{ PType, PData})

uit =

Table with properties:

Data: {'R' [391]}

ColumnWidth: 'auto'

ColumnEditable: []

CellEditCallback: ''

Position: [20 20 300 300]

Units: 'pixels'

Show all properties

Answer 2

[Walter Roberson]

PType = 'R';
PData = uint32(391);
app.LicksTable.Data = [PType,PData]

app = struct with fields:
    LicksTable: [1×1 struct]

app.LicksTable.Data

ans = 'RƇ'

The [] operation between a char and a uint32, is going to result in a single char array. That single char array is then the wrong size to populate the two-variable uitable.

You would have been better off using

app.LicksTable.Data = {PType,PData}

Answer 3

[Umar]

@Gavin and @Matt J,

I also wanted to share some documentation insights that might help clarify this mixed-type uitable issue.

To Gavin: You correctly identified that the table() constructor interprets char vectors as parameter names, which is why string conversion was necessary. However, for iterative row additions like yours, cell array syntax is more efficient:

   app.LicksTable.Data(end+1,:) = {PType, PData};

This eliminates both the char/string conversion step and the repeated table array construction overhead.

To Matt J: Your cell array solution is exactly the documented approach. For others reading this thread, it extends naturally to multiple rows:

uit.Data = {PType1, PData1; PType2, PData2; PType3, PData3};

Bottom line: For mixed-type uitable data, cell arrays are simpler and more performant than table array construction, especially when adding rows programmatically.

Hope this helps!