arXiv research

The estimation of optimal treatment regimes is of considerable interest to precision medicine. In this work, we propose a causal $k$-nearest neighbor method to estimate the optimal treatment regime. The method roots in the framework of causal inference, and estimates the causal treatment effects within the nearest neig…

The paper analyzes how much data points can be altered to change their rank in nearest neighbor searches.

Java implementation improves nearest neighbor algorithm complexity.

The paper explains how nearest neighbor methods succeed in prediction.

New methods use vector search and nearest-neighbor matching for policy learning in causal inference.

The nearest neighbor problem is defined as follows: Given a set $P$ of $n$ points in some metric space $(X,D)$, build a data structure that, given any point $q$, returns a point in $P$ that is closest to $q$ (its "nearest neighbor" in $P$). The data structure stores additional information about the set $P$, which is th…

This paper proposes a new hashing-based KNN technique for faster nearest neighbor selection.

We establish the first nonasymptotic error bounds for Kaplan-Meier-based nearest neighbor and kernel survival probability estimators where feature vectors reside in metric spaces. Our bounds imply rates of strong consistency for these nonparametric estimators and, up to a log factor, match an existing lower bound for c…

The stability of statistical analysis is an important indicator for reproducibility, which is one main principle of scientific method. It entails that similar statistical conclusions can be reached based on independent samples from the same underlying population. In this paper, we introduce a general measure of classif…

We provide finite-sample analysis of a general framework for using k-nearest neighbor statistics to estimate functionals of a nonparametric continuous probability density, including entropies and divergences. Rather than plugging a consistent density estimate (which requires $k \to \infty$ as the sample size $n \to \in…

This research examines how the error rate of nearest neighbor classifiers varies with dataset size.

Under-bagging $k$-NN improves performance on imbalanced classification.

Classification is an important supervised machine learning method, which is necessary and challenging issue for ecological research. It offers a way to classify a dataset into subsets that share common patterns. Notably, there are many classification algorithms to choose from, each making certain assumptions about the …

A clustering algorithm for natural hierarchical clusters with near-linear time complexity.

Integrates nearest neighbors with neural networks for more accurate treatment effect estimation.

Fast approximate nearest neighbor (NN) search in large databases is becoming popular. Several powerful learning-based formulations have been proposed recently. However, not much attention has been paid to a more fundamental question: how difficult is (approximate) nearest neighbor search in a given data set? And which …

A simple method flags images as out-of-distribution based on their distance to nearest neighbors.

A novel unsupervised outlier detection method using Randomized PCA Forest.

The paper investigates learning conditional distributions on multi-dimensional spaces using clustering and neural networks.

Study nearest-neighbor radii under dependent sampling, finding they remain informative.

Deep nearest neighbors outperform self-supervised methods in anomaly detection.

A new method for covariate shift adaptation using nearest neighbors.

Motivated by safety-critical applications, test-time attacks on classifiers via adversarial examples has recently received a great deal of attention. However, there is a general lack of understanding on why adversarial examples arise; whether they originate due to inherent properties of data or due to lack of training …

Characterizes Lebesgue points using nearest neighbor methods.

AWNN improves matrix completion by adaptively weighting nearest neighbors.

New estimator handles covariate shift with closed-form solution and super-efficiency.

A new method uses nearest neighbors for importance weighting.

In this paper, we develop four malware detection methods using Hamming distance to find similarity between samples which are first nearest neighbors (FNN), all nearest neighbors (ANN), weighted all nearest neighbors (WANN), and k-medoid based nearest neighbors (KMNN). In our proposed methods, we can trigger the alarm i…

We present simple and computationally efficient nonparametric estimators of Rényi entropy and mutual information based on an i.i.d. sample drawn from an unknown, absolutely continuous distribution over $\R^d$. The estimators are calculated as the sum of $p$-th powers of the Euclidean lengths of the edges of the `genera…

Nearest neighbor methods are a popular class of nonparametric estimators with several desirable properties, such as adaptivity to different distance scales in different regions of space. Prior work on convergence rates for nearest neighbor classification has not fully reflected these subtle properties. We analyze the b…

kNN-MTS improves MTS forecasting by using nearest neighbor retrieval over a large dataset.

The use of machine learning algorithms to address classification problems is on the rise in many research areas. The current study is aimed at testing the potential of using such algorithms to auto-select the best solvers for transport problems in uniform slabs. Three solvers are used in this work: Richardson, diffusio…

VNNGP uses nearest neighbors to approximate GPs, improving scalability and performance.

We consider model-free reinforcement learning for infinite-horizon discounted Markov Decision Processes (MDPs) with a continuous state space and unknown transition kernel, when only a single sample path under an arbitrary policy of the system is available. We consider the Nearest Neighbor Q-Learning (NNQL) algorithm to…

The paper tackles time series data by applying conformal prediction with nearest neighbors.

This paper analyzes kNN convergence over feature transformations.

Nearest-neighbor (NN) procedures are well studied and widely used in both supervised and unsupervised learning problems. In this paper we are concerned with investigating the performance of NN-based methods for anomaly detection. We first show through extensive simulations that NN methods compare favorably to some of t…

Proposes a new resampling method for off-policy evaluation in stochastic control.

A new multilabel classification framework improves ANN search performance.

K-Nearest neighbor classifier (k-NNC) is simple to use and has little design time like finding k values in k-nearest neighbor classifier, hence these are suitable to work with dynamically varying data-sets. There exists some fundamental improvements over the basic k-NNC, like weighted k-nearest neighbors classifier (wh…

In this work we explore the use of metric index structures, which accelerate nearest neighbor queries, in the scenario where we need to interleave insertions and queries during deployment. This use-case is inspired by a real-life need in malware analysis triage, and is surprisingly understudied. Existing literature ten…

The paper studies empirical processes from nearest neighbors in regression.

We consider a problem of multiclass classification, where the training sample $S_n = \{(X_i, Y_i)\}_{i=1}^n$ is generated from the model $\mathbb P(Y = m | X = x) = η_m(x)$, $1 \leq m \leq M$, and $η_1(x), \dots, η_M(x)$ are unknown $α$-Holder continuous functions.Given a test point $X$, our goal is to predict its labe…

Python package reduces hubness in high-dimensional data.

Locally adaptive nearest neighbors improve automated systems' performance and are easier to interpret.

The paper studies recovering hidden nearest neighbor graphs in large networks.

A new method for learning distance metrics for K-NN classification.

New method speeds up k-means clustering for large k by improving nearest-neighbor search.