Question

I have two example datasets, A and B below, that I want to join in Matlab to create C. The keys will be ‘product’ and ‘year’, but the problem is that the product number in dataset B only matches the one in A by the first 4 digits. Is there a way to join ‘almost’ matching numbers in this way?

 
A       
product tariff  year
202341  2       1999
202341  4       2000
202341  20      2008
202355  9       1999
202355  16      2000
438811  0       1999
438891  8       1999
438891  3       2001
671212  15      2005
671260  10      2005            

and

B       
product avg_tariff  year
2023    5,5         1999
2023    10          2000
2023    20          2008
4388    4           1999
4388    3           2001
6712    12,5        2005

are joined to produce matrix C

C           
product tariff  year    avg_tariff
202341  2       1999    5,5
202341  4       2000    10
202341  20      2008    20
202355  9       1999    5,5
202355  16      2000    10
438811  0       1999    4
438891  8       1999    4
438891  3       2001    3
671212  15      2005    12,5
671260  10      2005    12,5

Thanks in advance

Oscar

Answer 1

load the product array and treat it as strings using textscan:

fidA = fopen('A.txt');
fidB = fopen('B.txt');
A = textscan(fidA,'%s%s%s','delimiter',' ');
B = textscan(fidB,'%s%s%s','delimiter',' ');
fclose(fidA);
fclose(fidB);

keep only the first 4 chars of product in A

for i = 1:length(A{1})
   rowKeyA{i} = [A{1}{i}(1:4),A{3}{i}]; %product(1:4),year
end
for i = 1:length(B{1})
   rowKeyB{i} = [B{1}{i},B{3}{i}]; %product,year
end

now just find matches between rowKeyA and rowKeyB

for i = 1:length(rowKeyA)
    j = find(strcmp(rowKeyB,rowKeyA{i}),1);
    if(j)
       fprintf('%s %s %s\n',rowKeyA{i},A{2},B{2});
    end
end