Join two table variables into one. == does not works of table type

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Smithy
Smithy 2022-9-22
编辑： Stephen23 2023-1-3
Hello everybody,
I have two table variables, and would like to join them.
After comparing 1st column to 7th column of df3 and df4 variables,
if the row from 1st to 7th column is exactly same, then I hope to add the test2 column of df4
into dfcombine variable.
Please give me some helps.... == does not works of table type.
load input03.mat
dfcombine = df3;
for i=1:height(df3)
ind = find(df3(i,1:7)==df4(:,1:7));
dfcombine(i,9) = df4(ind,8);
end
I hope to make the dfcombine variable as below picture.

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采纳的回答

Karim
Karim 2022-9-22
Ran in:
I think one of the issues is the nan in the data, the result of nan == nan is something for philosophers :)
Anyhow, see below for a procedure to merge the tables as desired. The idea is to ignore the nan and empty values during the comparison.
load(websave('myFile', "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1132800/input03.mat"))
% have a look at the content of df3
df3
df3 = 5×8 table
OBJ_ID EQ_NO EQ_REVISION EQ_USER EQ_USER_ID SUBJECT T_GRP test1 _________ ____________ ___________ _________ __________ _______ ________ _____ {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2254 NaN {'R002'} 0.777 {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2255 NaN {'R002'} 1.222 {'0F850'} {'T070002F'} {'-'} {'Jo yu'} 2256 NaN {'R002'} 1.022 {'0F850'} {'T070002F'} {'-'} {'Jo yu'} 2257 NaN {'R002'} 1.122 {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2258 NaN {'R002'} 1.222
% have a look at the content of df4
df4
df4 = 3×8 table
OBJ_ID EQ_NO EQ_REVISION EQ_USER EQ_USER_ID SUBJECT T_GRP test2 _________ ____________ ___________ _________ __________ _______ ________ _____ {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2255 NaN {'R002'} 0.877 {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2254 NaN {'R002'} 0.222 {'0F850'} {'T070002F'} {'-'} {'Jo yu'} 2257 NaN {'R002'} 0.777
% use ismember function to check if the
[df4_check, df3_idx] = ismember( df4(:,[ 1 2 3 4 5]) , df3(:,[ 1 2 3 4 5]) );
% create a copy of the table, add a variable 'test2' filled with nan
test2 = nan(size(df3,1),1);
dfcombine = addvars(df3, test2);
% fill in the test values from df3
dfcombine(df3_idx,end) = df4(df4_check,end);
% have a look at the combined table
dfcombine
dfcombine = 5×9 table
OBJ_ID EQ_NO EQ_REVISION EQ_USER EQ_USER_ID SUBJECT T_GRP test1 test2 _________ ____________ ___________ _________ __________ _______ ________ _____ _____ {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2254 NaN {'R002'} 0.777 0.222 {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2255 NaN {'R002'} 1.222 0.877 {'0F850'} {'T070002F'} {'-'} {'Jo yu'} 2256 NaN {'R002'} 1.022 NaN {'0F850'} {'T070002F'} {'-'} {'Jo yu'} 2257 NaN {'R002'} 1.122 0.777 {'0F850'} {'T070002F'} {'-'} {'uo yu'} 2258 NaN {'R002'} 1.222 NaN

更多回答（2 个）

Walter Roberson
Walter Roberson 2022-9-22
You are doing () indexing on a table. The result would be a table row. You compare that to something else that is probably a table. But two tables can only compare if the variable names are the same... which we do not know to be true.
  1 个评论
Smithy
Smithy 2022-9-22
Thank you very much for your comments. Yes, you are right. It is the table and I was only possible to compare the variable name.

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HYEONSEOK SEOK
HYEONSEOK SEOK 2022-9-22
For comparing something with logical, table need to change to array
see as below:
clear all ; close all; clc;
load("input03.mat")
for i = 1:height(df3)
for j = 1:7
for k = 1:height(df4)
if sum(j == [5,6])
checker(k,j)=sum((df3{i,j}==df4{k,j}),1);
else
checker(k,j)=sum(strcmp(df3{i,j},df4{k,j}),1);
end
end
end
if sum(sum(checker,2) > 5) % if no nan value - change to 6
test2(i,1) = df4((sum(checker,2) > 5),8);
else
test2(i,1)= {NaN};
end
end
dfcombin = [df3,test2];

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