Extract Numbers from Mixed string

Hello, I have this string

 'single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'

Whats the best way to get the 4 numbers and then the S2R - S2L value?

I have tried this:

B='single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'
pat=regexpPattern("S2L:[/d]")
extract(B,pat)

But Im getting an empty array

[Jason]

Actually, this seems to work not sure if its th e best way:

sscanf(B,'single snap detector: 1 S2L:%d S2R:%d S3L:%d S3R:%d')
ans =
232867
3151621
0
0

Answer 1

[Hassaan]

% Your input string
B = 'single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0';

% Regular expression pattern to match the labels and their corresponding values
pattern = 'S2L:(\d+) S2R:(\d+) S3L:(\d+) S3R:(\d+)';

% Using regexp to find the matches and extract the numbers
tokens = regexp(B, pattern, 'tokens');

% tokens{1} will contain a cell array of the matched groups if a match is found
if ~isempty(tokens)
    % Converting the extracted strings to numbers
    numbers = str2double(tokens{1});
    S2L = numbers(1);
    S2R = numbers(2);
    S3L = numbers(3);
    S3R = numbers(4);
    
    % Calculate S2R - S2L
    difference = S2R - S2L;
else
    S2L = NaN;
    S2R = NaN;
    S3L = NaN;
    S3R = NaN;
    difference = NaN;
end

% Displaying the results
S2L, S2R, S3L, S3R, difference

S2L = 232867

S2R = 3151621

S3L = 0

S3R = 0

difference = 2918754

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Answer 2

[Vaibhav]

Hi Jason

You can consider using the below regular expression to extract the required values.

'S2L:(\d+) S2R:(\d+) S3L:(\d+) S3R:(\d+)'

Hope this helps!

Answer 3

[Stephen23]

B = 'single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0';

Method one: SSCANF:

V = sscanf(B,'%*[^:]:%d') % very efficient

V = 5×1

1 232867 3151621 0 0

Method two: REGEXP (could also be EXTRACT):

T = regexp(B,'(S\w+):(\d+)','tokens');
T = vertcat(T{:}) % all relevant parts

T = 4×2 cell array
    {'S2L'}    {'232867' }
    {'S2R'}    {'3151621'}
    {'S3L'}    {'0'      }
    {'S3R'}    {'0'      }

V = str2double(T(:,2))

V = 4×1

232867 3151621 0 0

[Jason]

Thanks Stephen, it was between you and the accepted answer, I wish I could accept both

[Stephen23]

@Jason: if you need only the numeric values and want efficient code then you won't get faster than the SSCANF call I showed you.

[Jason]

Yeah thats what Im actually using :-), thankyou!

Answer 4

[Mathieu NOE]

hello

i supposed you wanted to do this :

B='single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'

B = 'single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'

% pat=regexpPattern("S2L:[/d]")
pat=regexpPattern("S2L:[\d]")

pat = pattern
  Matching:

    regexpPattern("S2L:[\d]")

extract(B,pat)

ans = 1×1 cell array
    {'S2L:2'}

my2 cents suggestion to extract all numbers present in this char array (up to you to pick the ones you are intersted in);

B='single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'

B = 'single snap detector: 1 S2L:232867 S2R:3151621 S3L:0 S3R:0'

C = regexp(B,'\d+(\.)?(\d+)?','match');
% convert string to num array
for ci = 1:numel(C)
    out(ci,:) = str2double(C{ci});
end
out

out = 9×1

1 2 232867 2 3151621 3 0 3 0

[Jason]

Thnakyou for pointing out my error!