How to extract a number from a string array?

I have a string array of values that look like this: "(164) - (165)" "(165) - (166)" "(165) - (166)" How can extract the first three digit value only so that I get a matrix that is 164 165 165

[Dayne Coleman]

I am also trying to turn a string of Dates and times into a floating point value corresponding to the time. I have a string array that looks like: "Mon Jun 04 16:18:38 EDT 2018" "Mon Jun 04 16:33:29 EDT 2018" and I need a number array that has a decimal for the time of day. (12:00 am would be 0.000, noon would be 0.500)

[Juan Fernandez]

Have you looked through the documentation page for the sscanf(_) function? That might provide you a solution.

[Dayne Coleman]

Yes, I have tried sscanf(_). I don't know if it's a problem with my indexing or the function itself. Here is what I have:

>> whos str_node
Name           Size            Bytes  Class     Attributes

str_node      92x1              7248  string              

node=sscanf(str_node(:,1),'%f')
I'm getting an error that reads:
"First argument must be a string scalar or character vector."

[Dayne Coleman]

I got it to work using the strtok(_) function below. Let me know if there are faster, more efficient ways of doing it.

[token,remain]=strtok(str_node,'0,1,2,3,4,5,6,7,8,9');
parsed_node=strtok(remain,')');
node=str2double(parsed_node(:));

Answer 1

[Stephen23]

"How can extract the first three digit value only so that I get a matrix that is 164 165 165"

With a simple application of regexp and str2double:

>> C = {'(164) - (165)','(165) - (166)','(165) - (166)'};
>> str2double(regexp(C,'\d{3}','match','once'))
ans =
   164   165   165

Answer 2

[Juan Fernandez]

I searched through older questions and found a similar one from 2012. The solution requires the use of regexp(_). Here's my implementation.

str1 = '(164) - (165)';
str2 = '(165) - (166)';
str3 = '(165) - (166)';

 strs = {str1,str2,str3};
 output = zeros(length(strs),1);
 for iter=1:length(strs)
    num_strs = regexp(strs{iter},'\d*','Match');
    output(iter) = str2double(num_strs{1});
 end