How can I concatenate tables vertically?

How can I concatenate two or more tables vertically if they have the same headers?

Answer 1

[MathWorks Support Team]

To concatenate two or more tables vertically, you can use "vertcat" either as a function or as an operator - just as you would do to vertically concatenate two or more arrays. The headers do not even need be in the same order. Here is an example:

myTable1 = array2table(eye(3));
myTable1.Properties.VariableNames = ["One","Two","Three"];

myTable2 = array2table(2*eye(3));
myTable2.Properties.VariableNames = ["Two","Three","One"];

myTable3 = array2table(3*eye(3));
myTable3.Properties.VariableNames = ["Three","One","Two"];

myTable = [ myTable1; myTable2; myTable3 ]

The documentation page for "vertcat" explains that this function accepts table inputs:

https://uk.mathworks.com/help/matlab/ref/vertcat.html#mw_f3bbc20c-c8ab-4a50-b686-3c75b5d71eb4

[Leslie]

This answer was a great help to a problem I didn't know I had a week ago, thanks! But I have a follow-up question:

What if one has 3 tables because some of the columns contain information about incidence #1, #2, #3 ... of some phenomena? Is there a way to have myTables with a dimension for incidence?

To put this in concrete terms, I'm identifying low-level temperature inversions (LTIs) in data collected by weather balloons and keeping track of their starting and ending heights & temperatures. I'm allowing for the possibility of as many as 10 inversions, which means I have to hard-wire more than I would like to:

iLTI = 1; LTI = ones(nSonde)*iLTI;
Table1 = table([1:nSonde]',sondeTimeRelease(1:nSonde),...
               sondeSrc(1:nSonde), soundingTime,...
               LTI, lowInvBaseHt(:,iLTI), lowInvDepth(:,iLTI), lowInvBaseHt(:,iLTI)+lowInvDepth(:,iLTI), lowInvBaseT(:,iLTI), lowInvDT(:,iLTI), lowInvBaseT(:,iLTI)+lowInvDT(:,iLTI),...
          'VariableNames',{'Flight' 'DateUTC' 'Source' 'Sounding' 'Invers' 'BaseHt_m' 'Depth_m' 'TopHt_m' 'BaseT_C' 'deltaT_C' 'TopT_C'});
iLTI = 2; LTI = ones(nSonde)*iLTI;
Table2 = table([1:nSonde]',sondeTimeRelease(1:nSonde),...
               sondeSrc(1:nSonde), soundingTime,...
               LTI, lowInvBaseHt(:,iLTI), lowInvDepth(:,iLTI), lowInvBaseHt(:,iLTI)+lowInvDepth(:,iLTI), lowInvBaseT(:,iLTI), lowInvDT(:,iLTI), lowInvBaseT(:,iLTI)+lowInvDT(:,iLTI),...
          'VariableNames',{'Flight' 'DateUTC' 'Source' 'Sounding' 'Invers' 'BaseHt_m' 'Depth_m' 'TopHt_m' 'BaseT_C' 'deltaT_C' 'TopT_C'});
<etc.>

The code would be neater & more robust if I could create the 10 tables within a loop.

[Stephen23]

"...if I could create the 10 tables within a loop."

N = 10;
C = cell(1,N);
for k = 1:N
    C{k} = table(...)
end
vertcat(C{:})

Although most likely you would be better off using one table, as they are specifically designed to group data and process those groups, without requiring separate tables.