Speeding up comparison using strcmp
31 vues (au cours des 30 derniers jours)
Afficher commentaires plus anciens
Yongmin
le 13 Jan 2015
Commenté : Titus Edelhofer
le 13 Jan 2015
Hello! I have a list of approximately 2 million records and I would like to compare the records with a list of devices which generates those records. My code is as follows where "c" is the list of records and "device" is the list for distinct devices:
for ii = 1:length(device)
idx = ( strcmp(c,device(ii,:)) );
lidx = find(idx);
devid{ii} = lidx;
end
The problem is the above code takes too long time (more than an hour). Would you please tell me know how to reduce execution time?
Many thanks!
2 commentaires
Réponse acceptée
Titus Edelhofer
le 13 Jan 2015
Hi,
I would convert device to a cell array (using cellstr) and then call ismember without the loop, something like
cellDevice = cellstr(device);
[~, devid] = ismember(cellDevice, records);
Titus
3 commentaires
Titus Edelhofer
le 13 Jan 2015
I understand. In this case it might be hard without a loop. I'm not sure, but something like this could work then:
[~,idx] = ismember(records, cellDevice);
devid = cell(numel(cellDevice), 1);
for ii=1:length(devid)
devid{ii} = find(idx==ii);
end
Titus
Plus de réponses (1)
David Sanchez
le 13 Jan 2015
If you have getnameidx available in your system, you might transform your device to a cell:
device_cell = celstr(device);
and then look for their position within c:
device_positions = getnameidx(c,device_cell);
which will return the position of your devices within the c cell
Voir également
Catégories
En savoir plus sur Logical dans Help Center et File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!