Table array with numerical row names

I'm trying to create a table array where the row names are a vector of doubles, but row names are required to be a cell array of strings. How would someone do this?

Answer 1

[Guillaume]

Convert your numbers to a cell array of char array (strings are not supported strangely). If the vector of numbers is all integers:

rownames = compose('%d', yourvector);

If it's real numbers then specify the appropriate format string in compose or matlab let do its thing with:

rownames = cellstr(string(yourvector));

Then create your table whichever way you were going to use, e.g.:

t = array2table(somearray, 'RowNames', rownames)

Answer 2

[Sean de Wolski]

You could use matlab.lang.makeValidName to make valid names for each one. However, for the numeric case, this just adds x so you could do that directly and choose another letter or word, perhaps r or row:

matlab.lang.makeValidName(string(1:10))
ans = 
  1×10 string array
    "x1"    "x2"    "x3"    "x4"    "x5"    "x6"    "x7"    "x8"    "x9"    "x10"

Or

"r"+(1:10)

[Emiliano Alexander Carlevaro]

Mmmm... It doesn't seem to work anymore...

>> matlab.lang.makeValidName(string(1:10))
Error using matlab.lang.makeValidName (line 72)
First input must be a character vector or cell vector of character
vectors.

[Walter Roberson]

Emiliano Alexander Carlevaro which release are you using? And have you accidentally defined a variable named string ?

Answer 3

[Elias Gule]

Convert your vector of strings to a cell array of strings.

   v = 1 : 20;     % replace with your vector
   row_names = arrayfun(@num2str,v,'uni',0);

[Guillaume]

strings are actually not supported for row names. The cell array must contain char vectors

Note that the above does create a cell array of char vectors, not strings.

Answer 4

[Peter Perkins]

The variable names in a table not only need to be text, they also need to be valid MATLAB identifiers (as do the field names in a struct). So while you might think to do this ...

>> t = table([1;2;3],[4;5;6],'VariableNames',{'1' '2'})
Error using table (line 307)
'1' is not a valid variable name.

... you can't. But hang on a minute - create this table:

>> t = table([1;2;3],[4;5;6],'VariableNames',{'one' 'two'})
t =
  3×2 table
    one    two
    ___    ___
     1      4 
     2      5 
     3      6

Now index into it using the numbers you'd like to have as the variable names:

>> t(:,1:2)
ans =
  3×2 table
    one    two
    ___    ___
     1      4 
     2      5 
     3      6 
>> t{:,1:2}
ans =
     1     4
     2     5
     3     6

and even

>> t.(1)
ans =
     1
     2
     3

What is it that you can't do right now, except have '1' displayed as the name?

[math man]

For me, the idea is to have a set of Variable names which I can read in from elsewhere (perhaps a vector of 15 to 20 numbers). I'd then like to be able to refer to them. So ideally I'd have a set of variablesnames which I can call dynamically (NOT just assigning 'One', 'Two', etc.), and also which I can refer to for the purposes of Indexing, like in Excel.

so

numbervariablenames = otherarray(1,:)
t = table(somedata,'VariableNames',numbervariablenames)

and I want to be able to do:

Col = find(strcmp(t.VariableNames,num2str(SomeNumber)),1)
ColumnofData_Iwant = t{:,Col}

Note that the earlier solution by Guillame did not work for me, I get this error:

Error using table.init (line 401)

'2.96926' is not a valid variable name.

Error in array2table (line 64)

t = table.init(vars,nrows,rownames,nvars,varnames);

Thanks for any help!

[Peter Perkins]

In one of the 2019 releases (I forget which), the requirement that table/timetable variable names be valid MATLAB identifiers was relaxed. So this

>> t = array2table(rand(5,3),'VariableNames',["1" "2 2" "(3)"])
t =
  5×3 table
       1          2 2        (3)  
    ________    _______    _______
     0.69875    0.47992    0.80549
     0.19781    0.90472    0.57672
    0.030541    0.60987    0.18292
     0.74407    0.61767    0.23993
     0.50002    0.85944    0.88651

is a legal table now. Of course, to access those variables, t.1 or t.2 2 isn't gonna work, so you need to do this:

>> t.("1")
ans =
      0.69875
      0.19781
     0.030541
      0.74407
      0.50002