Comparing two tables and copy elements of table 2 into table 1
2 次查看(过去 30 天)
显示 更早的评论
Hi,I have two tables as given below.
Table 1:
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/208457/image.png)
Table 2
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/208458/image.png)
If column1 in table 2 is equal to column 1 in table1 T & W values in table 2 has to copy in table 1, Similar strings has to follow one after the other. If the stings are unequal T & W must be empty. I want the output as below table;
![image.PNG](https://www.mathworks.com/matlabcentral/answers/uploaded_files/208558/image.png)
2 个评论
dpb
2019-3-14
Your new table now has three 'hi' records instead of original two but only two 'hello'.
What's the difference and what's the logic behind such that could be written?
采纳的回答
Guillaume
2019-3-14
%create demo tables
ID = strsplit('hello new world hi hello hi')';
T = cell(6, 1); W = T;
V = [1; 2; 3; 5; 8; 7];
T1 = table(ID, T, W, V)
T2 = table(ID(4:5), {2;4}, {6;7}, [1;2], 'VariableNames', {'ID', 'T', 'W', 'V'})
%merge the two tables
[found, where] = ismember(T1.ID, T2.ID);
T1(found, {'T', 'W'}) = T2(where(found), {'T', 'W'})
3 个评论
Ayse YILMAZ
2021-4-19
Hello Guillaume;
Firstly thank you for your helpful sharing. I have a question about your answer.
When I run your code in Matlab, it returns 0 as the value that is not in T2. I wonder if there is a way to return it as space or NAN or something else? What code should I write for this?
Another question is what should I do for more than two tables comparison (7 or 8 tables)?
Thank you in advance for your answer.
更多回答(2 个)
Pruthvi G
2019-3-14
Use
strcmp
if the values are matching then add the values to the T and W column
1 个评论
Peter Perkins
2019-3-20
This is just an outer join:
>> T1 = table(["hello";"new";"world";"hi";"hello";"hi"],[1;2;3;5;8;7],'VariableNames',["Word" "V"])
T1 =
6×2 table
Word V
_______ _
"hello" 1
"new" 2
"world" 3
"hi" 5
"hello" 8
"hi" 7
>> T2 = table(["hi";"hello"],[2;4],[6;7],'VariableNames',["Word" "T" "W"])
T2 =
2×3 table
Word T W
_______ _ _
"hi" 2 6
"hello" 4 7
>> outerjoin(T1,T2,'MergeKeys',true)
ans =
6×4 table
Word V T W
_______ _ ___ ___
"hello" 1 4 7
"hello" 8 4 7
"hi" 5 2 6
"hi" 7 2 6
"new" 2 NaN NaN
"world" 3 NaN NaN
1 个评论
Guillaume
2019-3-20
编辑:Guillaume
2019-3-20
Do'h! I did try using an outerjoin but using only Word as the key hence got duplicate V, T and W in the result, which I couldn't merge. Of course, If you use all columns as keys, then you get the correct outerjoin.
Note that since the data is stored in a database you don't need matlab to do the join. In SQL it'd be something like:
SELECT * FROM table1 FULL OUTERJOIN table2 ON table.Word = table2.Word
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Matrices and Arrays 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!