Eliminating duplicate columns in a table when appending

Question

Danielle Leblance 2017-2-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/323442-eliminating-duplicate-columns-in-a-table-when-appending

评论： nikhilthoppil 2020-4-10

采纳的回答： the cyclist

在 MATLAB Online 中打开

Hi,

I am importing data using readtable function. but when i append data using:

mytable=[mytable mytable2];

I receive an error: Duplicate variable name: 'ID' because every file contains the ID of the firm. I need the column ID only once. so how can i skip the ID column in mytable2 when i want to append?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

the cyclist 2017-2-5

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/323442-eliminating-duplicate-columns-in-a-table-when-appending#answer_253407

编辑：the cyclist 2017-2-5

在 MATLAB Online 中打开

Use the join command. Here's a simple example.

% Set up some sample data
id = [1 2 3]';
firstName = {'Walter','Image','Star'}';
lastName = {'Roberson','Analyst','Strider'}';
tableFirst = table(id,firstName);
tableLast  = table(id,lastName);
% Join the tables
tableFirstAndLast = join(tableFirst,tableLast)

FYI, there are many input options that govern how the variables in the two tables are retained when there are duplicates, so I suggest carefully reading the documentation (linked above) if this example doesn't do exactly what you want in your case.

You might also need a different function from that family, e.g. innerjoin.

6 个评论
显示 4更早的评论隐藏 4更早的评论

the cyclist 2017-2-5

在 MATLAB Online 中打开

The proximate cause is that some of the tables contain a row with NaN as the value of IDRSSD. Because one NaN is not equal to another NaN, MATLAB cannot join those rows.

One simple solution might be to replace those values of NaN with some other unique identifier. (It looks like setting IDRSSD=0 would work.)

You could also use the innerjoin() function, as I mentioned earlier, which will only use matching rows.

a2=innerjoin(t7,t8);

Or you could manually avoid that first row for those tables:

a2 = join(t7(2:end,:),t8(2:end,:))

but that seems pretty inelegant.

The approach to take will depend on exactly what output you want, and what is more readable and efficient.

nikhilthoppil 2020-4-10