[R] Identyfing rows with specific conditions

[Allaisone 1]

Hi All..,

I have 2 tables. The first one contains 2 columns with the headers say "meal A code" & "meal B code " in a table called "Meals" with 2000 rows each of which with a different combination of meals(unique combination per row).


>Meals

    meal A code      meal B code

1          34                   66

2           89                  39

3           25                   77

The second table(customers) shows customers ids in the first column with Meals codes(M) next to each customer. There are about 300,000 customers (300,000 rows).

> Customers
     1         2     3       4    ..30
     id       M1  M2   M3
1   15      77    34    25
2   11      25    34     39
3    85     89     25    77
.
.
300,000

I would like to identify all customers ids who have had each meal combination in the first table so the final output would be the first table with ids attached next to each meal combination in each row like this:

>IdsMeals


  MAcode  MBcode  ids

1     34        39            11

2     25       34              15   11

3      25     77                15   85

Would you please suggest any solutions to this problem?

Regards

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