How to use "contains" statement to detect a string without ambiguity?

Hi to everyone,

I have a table with some data (attached file table.mat ). In the second column named " Sol_inters " I have three types of data (strings):

A

B

A & B

I want to filter the original table in order to create three filtered tables (tab_A, tab_B, tab_AB) in which their second column contains respectively "A", "B" and "A & B". So, for each table I want to mantain only rows that satisfy the condition on second column.

I 'm trying to use the "contains" statement but it fails with cases "Sol_filtered_A " and "Sol_filtered_B" becasue it maintans always also the case "A & B".

Here is my code:

% Import general solution
Sol_data = readtable('All_database_solution_test.csv','VariableNamingRule','preserve');

% Filter solutions: select if the solution occurs in point A, B or both
Sol_A = contains(Sol_data.Sol_inters,'A','IgnoreCase',false);
Sol_B = contains(Sol_data.Sol_inters,'A','IgnoreCase',false);
Sol_AB = contains(Sol_data.Sol_inters,'A & B','IgnoreCase',false);
Sol_filtered_A = Sol_data(Sol_A,:);
Sol_filtered_AB = Sol_data(Sol_AB,:);

Can you help me to solve this issue?

Answer 1

[Stephen23]

"Can you help me to solve this issue?"

CONTAINS() check if the pattern occurs anywhere inside the string, but this could be a substring. So if you want match only the entire string then you need to use the correct tool: MATCHES() or STRCMPI()

[Giuseppe]

Hi @Stephen23, can you show me an example by using the code in my question?

Can you also tell me what is the difference bewteen two tools you mentioned?

[Steven Lord]

The documentation pages for the matches and strcmpi functions each contain multiple examples showing what each function does.

If you had to use contains (as a requirement of a homework assignment, for instance) remember that contains returns a logical value, one that you can use with the & (and), | (or), and ~ (not) operators.

true & false % false

ans = logical
   0

true & ~false % true

ans = logical
   1