Joining Tables and deleting columns

Hi everyone,

How can I add two tables into a third table and how can I delete columns in a third table.

I have two tables which only contains 1 column of information. However, the information is required to replace data contained under two headings in another table - SecondVID and FirstVID.

How can I take the column data of the two tables and insert it into the third?

[Matt J]

We'd probably need an example.

[Cris LaPierre]

Context: https://www.mathworks.com/matlabcentral/answers/1936104-matching-values-from-one-table-to-another?s_tid=srchtitle

[Peter Perkins]

This seems like essentiallyt the same question as asked in

https://www.mathworks.com/matlabcentral/answers/1936104-matching-values-from-one-table-to-another?s_tid=prof_contriblnk

You've used the word "join", and there are join methods for tables, but I think that kind of join is overkill. I think all you want to do (if the previous question is any indication) is find values from one variable that are in another variable, and overwrite them. ismember is what I think you need.

x = [1;2;3;4;5];
y = [1;3;5];
x(ismember(x,y)) = NaN

x = 5×1

NaN 2 NaN 4 NaN

Now do that with variables in your tables, using, like, t1.Var1 and t2.Var2. In your previous question, you asked to overwrite numbers with text, which is not going to work unless you use cell arrays, which, you don't want to do that. I recommend you start with text, in other words, treat 1,2,3 as identifiers, not as numbers.

x = ["1";"2";"3";"4";"5"];
y = ["1";"3";"5"];
x(ismember(x,y)) = "Howdy!"

x = 5×1 string array
    "Howdy!"
    "2"
    "Howdy!"
    "4"
    "Howdy!"

[Jana Sarran]

Thank you for your response. This question was posted as another step that has to be taken after the data was sorted in the previous question.

I need to use the table format for my dataset to obtain my final results in matlab. Additionally, my dataset is larger over 3000 rows. Hence, I do not think treating the data as identifiers is possible. Maybe you can advise on this.

In summary this is what I want to achieve:

Step 1: I would like to search Table 2 for the values in Table 1

TABLE 1

TABLE 2

Step 2: Once similar values are found, I would like the "Similar" values identified in coloumns "FirstVID" and "SecondVID" to be updated with the words "AV".

I would like this to update Table 2. As opposed to generating a different table for only FirstVID and SecondVID. In other words the table would appear like:

I would also like to replace the other IDs to DVs. Example, 1348 should be "DV"

NOTE; The table has a large number of rows. Also, I would like to use the index function (idx) to sort the data in the TTC column. I can not do this if the data is a string.

Thank you for your assistance.

[Peter Perkins]

I'm pretty sure my previous post exactly answered what you've described:

• Find values from one vector in another vector.
• Replace the values in the other vector with something else.
• The something else is text.

Answer 1

[Swaraj]

Step 1: Joining two tables

You can join two tables in MATLAB using the “join()” function.

Eg. Table3 = join(table1,table2);

Documentation for “join()”:

Combine two tables or timetables by rows using key variables - MATLAB join (mathworks.com)

Step 2: Removing a column from the third table.

You can use “removevars” function.

Documentation for “removevars” function.

Delete variables from table or timetable - MATLAB removevars (mathworks.com)