How to replace 1 column in table

Question

Cside 2023-8-2

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评论： Sachin 2023-8-3

Hello!

I have a NaN table (100x200), lets call it A, and a large dataset with first column being participants ID (eg 123AJH), lets call this B. I want to find the unique participant ID in B (:,1) (eg there are 100 unique IDs as many of them are repeated) and replace the unique IDs as the first column of A. However, the result is 1,2,...100 (the number of unique ID) rather than the ID itself (123AJH).

Anyone knows how to replace 1st column of A with the column of unique IDs found in B (123AJH; 232AJH, ...) ?

Much appreciated thank you. The code I wrote is below:

A (:,1) = unique (B(:,1));

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Dyuman Joshi 2023-8-2

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Answer 1

Sachin 2023-8-2

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Hi Cside,

I understand that you want to replace 1 column in table.

Following steps might be helpful to you :

First find the unique values in Table B using "unique".
Find the count of those unique values using function "length".
Create a vector representation from 1 to count.
Then assign the values to the Table A.

dummyTableA = [2,3;3,4;4,5]; %dummy table a
Age = [38;43;38;40;38];
unique_Age = unique(Age)  % find the unique values
unique_Age = 3×1
    38
    40
    43
count_uniqueAge = length(unique_Age)  % find the count of unique values
count_uniqueAge = 3
unique_ids = [1:1:count_uniqueAge]  % create a vector 
unique_ids = 1×3
     1     2     3
dummyTableA
dummyTableA = 3×2
     2     3
     3     4
     4     5
dummyTableA(:,1) = unique_ids;  % update the value of column 1 in table A
dummyTableA  
dummyTableA = 3×2
     1     3
     2     4
     3     5