nnr

nnr is an acronym that can refer to several distinct concepts, organizations, or methods, depending on the context.

In environmental protection, National Nature Reserve (NNR) is a designation used in some countries to designate protected areas that conserve important habitats and wildlife. In the United Kingdom, NNRs are typically established to safeguard rare species, sensitive ecosystems, and significant landscapes, with management plans often drawn up by national or regional conservation agencies. These reserves commonly allow for public access and educational interpretation while prioritizing habitat preservation and species protection.

In rail heritage, the North Norfolk Railway (NNR) is a heritage railway line in Norfolk, England. Also known as the Poppy Line, it operates steam and diesel services over a short network and is a focal point for preservation and tourism activities in the region.

In statistics and machine learning, Nearest Neighbor Regression (NNR) is a non-parametric regression technique. It estimates the value of a target variable for a given input by averaging the outcomes associated with its nearest neighbors in the training data. Variants may use different numbers of neighbors (k) or distance metrics, and the method is valued for its simplicity and flexibility in capturing nonlinear relationships.

Because acronyms like nnr have multiple legitimate meanings across domains, identifying the intended reference relies on surrounding context, including the field, location, and accompanying terms. If a specific usage is in mind, providing additional context can clarify which NNR is being discussed.