# Data Cleansing in Tables

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Furqan Hashim on 24 Sep 2020
Commented: Sindar on 25 Sep 2020
I want to clean a data table and create a new table/overwrite the incorrect one. To create a dummy case run following code to create a table
test = table();
test.index = ['11'; '12'; '13'; '14'; '15';'16'];
test.id = ['A'; 'B'; 'C'; 'D';'E';'Z'];
test.id2 = ['B'; 'C'; 'D'; 'E'; 'F'; 'Z'];
test.price = [1;2;3;4;5;6];
test.price1 = [10;20;30;40;50;60];
The output of the table is
index id id2 price price1
_____ __ ___ _____ ______
11 A B 1 10
12 B C 2 20
13 C D 3 30
14 D E 4 40
15 E F 5 50
16 Z Z 6 60
In above table index of table is properly aligned with id2 and price, and id is properly aligned with price1. Based on this knowledge I want to create a new table with correct data. Desired Output:
index id price price1
_______ __ _____ ______
{[NaN]} A NaN 10
{'11' } B 1 20
{'12' } C 2 30
{'13' } D 3 40
{'14' } E 4 50
{'15' } F 5 NaN
{'16' } Z 6 60
Since for id A we do not index so we will assign it NaN Similarly price is also not avaliable so we can keep that NaN but we do have price1 so we keep that. For id B we have index and price from 1st row of faulty table and we can extract price1 from the next row of faulty table to create 2nd row of desired output. What is optimal way to achieve this using MATLAB code. Also note that distinct values from id and id2 should all be in id of desired output.

Sindar on 24 Sep 2020
Edited: Sindar on 25 Sep 2020
test_rejoined = outerjoin(test(:,[1 3 4]),test(:,[2 5]),'LeftKeys','id2','RightKeys','id','MergeKeys',true);
• separate table into two tables, each with aligned columns
• use outerjoin to merge these tables based on the shared key
edited: strings > chars since older versions of Matlab often only accepts chars (single quotes) not strings (double quotes). In 2017b, table variable names must be passed as chars
Sindar on 25 Sep 2020
edited the answer since it will work in 2017b and newer versions

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