"could classify" is correct and usable in written English.
You may use it to indicate a potentiality or a possibility. For example: "We could classify the data according to its different characteristics."
Our classifier could classify the 311 training samples into their subtypes with an overall accuracy of 87%% in LOOCV.
"They are concerned that the government could classify some of their legitimate activity as being snoopable.
But the test could classify only 64percentt of unknown tumors.
It involves operations, almost daily operations, which we could classify as criminal under any definition.
We could classify the examples collected under different perspectives (see below).
Employing this method we could classify flow regimes with 98% accuracy.
We could classify earnings for tax purposes as "creating wealth" or "gathering wealth".
Although I doubt you could classify Stanišić as a kitchen-sink realist, he does have some witty political observations.
"The best way I could classify it is they're on one end of the spectrum and we're on the other.
I guess that one could classify this as a case of the American preference for machinery over manual labor.
We applied this algorithm to published siRNAs, and could classify effective and ineffective siRNAs with 90.6%, 86.2% accuracy, respectively.
