Appending 2 Tables with different column order and different number of columns
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Hi,
I need to append tables with different column orders but have the same header for the respecitve columns. For example
A.Properties.VariableNames={'org01','org02','org03','org04',SQ001','SQ002',SQ003'};
B. Properties.VariableNames={'org01','org03','org02',SQ002','SQ003',SQ001'};
How can I append B columns to A columns for the columns that have the same header while assigning for the variables in A that don't have equivalent in B such as org04 NaN values.
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Accepted Answer
Cris LaPierre
on 10 Jan 2021
Edited: Cris LaPierre
on 10 Jan 2021
MATLAB can use variable names in a table to concatenate two tables even if the order is different. When all the variables are in all tables, use the normal vertical concatenation technique.
It's more challenging if all tables do not have all the variables. MATLAB will fill the unassigned variable(s) with the default value for the datatype. That is 0 for doubles, not NaN (see the warning message below)
% Create 2 tables
org01=(1:5)';
org02=org01;
SQ001=org01;
T1 = table(org01,org02,SQ001)
% Table 2 is a subset of the variable of T1
T2 = flip(T1(:,["SQ001","org01"]))
% Add T2 variable values to T1
T1(end+1:end+height(T2),T2.Properties.VariableNames)=T2
If you really want them to be NaN, there are a couple options. If you want to make all 0s NaN, look into the standardizemissing function. If there will be zeros elsewhere you don't want to change to NaN, you can use a comparison of variable names along with some indexing to set just the extended variables to NaN. Here's an eample.
% Identify the new rows, and just the variables that were not in T2
T1{end-height(T2)+1:end,~ismember(T1.Properties.VariableNames,T2.Properties.VariableNames)}=NaN
6 Comments
Cris LaPierre
on 12 Jan 2021
I'm not aware of a way to do this all at once.
You might find the following aswers helpful.
- https://www.mathworks.com/matlabcentral/answers/153538-how-can-i-typecast-a-column-in-a-table-to-a-particular-data-type-in-matlab
- https://www.mathworks.com/matlabcentral/answers/347783-change-table-variable-data-type
- https://www.mathworks.com/matlabcentral/answers/429348-how-to-change-data-type-of-table-in-matlab
Marcus Glover
on 24 Feb 2024
Edited: Marcus Glover
on 24 Feb 2024
Just wanted to add this helped me out and add my last line to anyone looking to remove a row that does not appear in the new table
% Remove rows that were not in T2
T1(:,~ismember(T1.Properties.VariableNames,T2.Properties.VariableNames))=[]
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