On the Models of Spatial Patterns Composed of Circles of Equidistant Radii and a Method of Analysing Spatially Distributed Facilities through the Probability Density Function of Nearest-neighbor Distance

1991 ◽  
Vol 26 (0) ◽  
pp. 529-534
Author(s):  
Kiyoaki Oikawa
1988 ◽  
Vol 20 (5) ◽  
pp. 609-620 ◽  
Author(s):  
A Okabe ◽  
T Yoshikawa ◽  
A Fujii ◽  
K Oikawa

The objective of this paper is to formulate a statistical method of testing the hypothesis that the distribution of activity points (such as retail stores) is independent of location of ‘surface-like’ infrastructural elements (such as parks). In order to do this, first, the probability density function of a distance from a random point to the nearest surface-like element is derived. Second, through the use of this function, a measure, R, of spatial dependency on the surface-like elements is defined as the ratio of the average nearest-neighbor distance to the expected average nearest-neighbor distance. This measure is an extension of the ordinary nearest-neighbor distance measure frequently referred to in geography and ecology. Third, the statistical use of measure R is shown. Fourth, as this measure is difficult to compute geometrically, the computational method of calculating the value of R is developed. Last, by use of this method, a test is conducted to decide whether or not the distribution of high-class apartment buildings in Setagaya, Tokyo, is affected by the location of big parks.


1995 ◽  
Vol 73 (7) ◽  
pp. 1375-1379 ◽  
Author(s):  
Martha J. Desmond ◽  
Julie A. Savidge ◽  
Thomas F. Seibert

The spatial patterns of burrowing owl (Speotyto cunicularia) nests in black-tailed prairie dog (Cynomys ludovicianus) towns were examined in the Nebraska panhandle during the spring and summer of 1989–1991. Because of higher nest densities (≥ 0.20 nests/ha) and internest distance requirements, it was not possible for owls to demonstrate patterns other than random in the smaller (< 35 ha) prairie dog towns. In large prairie dog towns (> 35 ha), burrowing owls were less dense (≤ 0.20 nests/ha), and choice of nest sites by pairs resulted in a clumped nest distribution. In prairie dog towns < 35 ha, nearest neighbor distance was positively related to prairie dog town size, whereas no relationship was found between prairie dog town size and nearest neighbor distance for towns ≥ 35 ha. Burrow availability was not responsible for clumping. Ample burrows were available throughout the towns in 1990 and 1991. In 1991, two towns with clumped distributions of owls showed no differences in numbers of burrows around active owl nests and random burrows throughout the towns. Other possible explanations for clumping, including food availability and reduced predation risk, are discussed.


2022 ◽  
Vol 8 ◽  
pp. e790
Author(s):  
Zsigmond Benkő ◽  
Marcell Stippinger ◽  
Roberta Rehus ◽  
Attila Bencze ◽  
Dániel Fabó ◽  
...  

Data dimensionality informs us about data complexity and sets limit on the structure of successful signal processing pipelines. In this work we revisit and improve the manifold adaptive Farahmand-Szepesvári-Audibert (FSA) dimension estimator, making it one of the best nearest neighbor-based dimension estimators available. We compute the probability density function of local FSA estimates, if the local manifold density is uniform. Based on the probability density function, we propose to use the median of local estimates as a basic global measure of intrinsic dimensionality, and we demonstrate the advantages of this asymptotically unbiased estimator over the previously proposed statistics: the mode and the mean. Additionally, from the probability density function, we derive the maximum likelihood formula for global intrinsic dimensionality, if i.i.d. holds. We tackle edge and finite-sample effects with an exponential correction formula, calibrated on hypercube datasets. We compare the performance of the corrected median-FSA estimator with kNN estimators: maximum likelihood (Levina-Bickel), the 2NN and two implementations of DANCo (R and MATLAB). We show that corrected median-FSA estimator beats the maximum likelihood estimator and it is on equal footing with DANCo for standard synthetic benchmarks according to mean percentage error and error rate metrics. With the median-FSA algorithm, we reveal diverse changes in the neural dynamics while resting state and during epileptic seizures. We identify brain areas with lower-dimensional dynamics that are possible causal sources and candidates for being seizure onset zones.


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