Reorder Table Rows and columns Matlab - matlab

Question

I have a 5x5 table:
a b c d e
a 1 2 3 4 5
b 3 5 7 2 6
c 1 3 4 6 1
d 4 4 1 7 8
e 6 7 2 1 6
where the headers are the strings.
I want to know how to reorder the table rows and columns using the headers
so for example of I wanted them to be in this order e b c a d then this will be the table:
e b c a d
e 6 7 2 6 1
b 6 5 7 3 2
c 1 3 4 1 6
a 5 7 3 1 4
d 8 4 1 4 7

Answer 1

Let the table be defined as
T = table;
T.a = [1 3 1 4 6].';
T.b = [2 5 3 4 7].';
T.c = [3 7 4 1 2].';
T.d = [4 2 6 7 1].';
T.e = [5 6 1 8 6].';
And let the new desired order be
order = {'e' 'b' 'c' 'a' 'd'};
The table can be reordered using just indexing:
[~, ind] = ismember(order, T.Properties.VariableNames);
T_reordered = T(ind,order);
Note that:
To reorder only columns you'd use T_reorderedCols = T(:,order);
To reorder only rows you'd use T_reorderedRows = T(ind,:);
So in this example,
T =
a b c d e
_ _ _ _ _
1 2 3 4 5
3 5 7 2 6
1 3 4 6 1
4 4 1 7 8
6 7 2 1 6
T_reordered =
e b c a d
_ _ _ _ _
6 7 2 6 1
6 5 7 3 2
1 3 4 1 6
5 2 3 1 4
8 4 1 4 7

Answer 2

Here is a way to do it using indexing. You can indeed re-arrange the rows and columns using indices as you would for any array. In this case, I substitute each letter in the headers array with a number (originally [1 2 3 4 5]) and then, using a vector defining the new order [5 2 3 1 4], re-order the table. You could make some kind of lookup table to automate this when you deal with larger tables:
clc
clear
a = [1 2 3 4 5;
3 5 7 2 6;
1 3 4 6 1;
4 4 1 7 8;
6 7 2 1 6];
headers = {'a' 'b' 'c' 'd' 'e'};
%// Original order. Not used but useful to understand the idea... I think :)
OriginalOrder = 1:5;
%// New order
NewOrder = [5 2 3 1 4];
%// Create table
t = table(a(:,1),a(:,2),a(:,3),a(:,4),a(:,5),'RowNames',headers,'VariableNames',headers)
As a less cumbersome alternative to manually creating the table with the function table, you can use (thanks to #excaza) the function array2table which saves a couple steps:
t = array2table(a,'RowNames',headers,'VariableNames',headers)
Either way, re-arrange the table using the new indices:
New_t = t(NewOrder,NewOrder)
Output:
t =
a b c d e
_ _ _ _ _
a 1 2 3 4 5
b 3 5 7 2 6
c 1 3 4 6 1
d 4 4 1 7 8
e 6 7 2 1 6
New_t =
e b c a d
_ _ _ _ _
e 6 7 2 6 1
b 6 5 7 3 2
c 1 3 4 1 6
a 5 2 3 1 4
d 8 4 1 4 7