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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def cos_r(self, N=None):
 # percent=0.9 		"""Return the squared cosines for each row."""


		if not hasattr(self, 'F') or self.F.shape[1] < self.rank:
			self.fs_r(N=self.rank)  # generate F
		self.dr = norm(self.F, axis=1)**2
		# cheaper than diag(self.F.dot(self.F.T))?

		return apply_along_axis(lambda _: _/self.dr, 0, self.F[:, :N]**2)