‘I’m not a criminologist,” Mayor de Blasio admits — but it seems he wants to play one on TV.

Because he inserted that qualifier right before suggesting that one reason for the recent wave of slashings and stabbings is that the NYPD has gotten so many guns out of the community.

“I can safely say that guns are being taken off the street in an unprecedented way,” the mayor claimed. And then: “Some people, unfortunately, are turning to a different weapon.”

OK, he made the remarks while paying tribute to the NYPD’s anti-gun efforts. But what a dumb thing to say.

Fact is, the end of widespread stop-and-frisk almost surely has thugs (and those who fear them) carrying guns more often these days. The police have done a remarkable job of adapting tactics to still keep crime down — but then there’s that disturbing, mysterious rash of knife crimes.

Forget the mayor’s idiotic attempt to make knife attacks seem like good news. The best hint so far of what’s really driving the slashing outbreak came on Page 5 of Friday’s Post: that stunning photo of some of the dozens upon dozens of blades confiscated in a single day at city homeless shelters.

The weapons included a cleaver, a hay hook and a razor-sharp wood scraper — plus a host of daggers, box-cutters and switchblades.

New Yorkers can safely assume there are even more knives on the streets than in the shelters. Indeed, an NYPD source notes, “The lion’s share of random slashings are EDPs [emotionally disturbed persons] who are not getting the psychiatric help they need.”

We have no desire to demonize the homeless — but every New Yorker knows that some of them are just plain scary.

Hey, Mr. Mayor: How about taking a break from goofy pseudo-criminology to tell your entire administration it’s time to confront the threat to public safety from knife-wielding madmen?