Questions tagged [point-process]
A point process is a stochastic process in which the data are sets of points ordered in a mathematical space. A common example is the Poisson process, in which points are ordered in time with the interarrival times exponentially distributed.
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Distance between point process realizations
Is there a valid distance metric for measuring how similar are the realisations of two point processes? E.g. let's say we simulate two histories $ h_1, h_2 $ in the time interval $ [0, T] $ for two ...
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1answer
109 views
Ripley K function value in a specific radius and dataset using R's Kest function
I'm having general trouble with calculating Ripley's K function values.
The following is a simple spatial point pattern, where both X and Y range from 0 to 200:
Here's its corresponding Ripley K ...
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24 views
Inhomogeneous K-function to indicate need for spatial dependence/interaction term in Poisson point process model
I am mapping and modelling a disease of sheep. I have approx 4200 point locations in my dataset, each of which represents the centroid of a given sheep farm.
I have created a K-function difference ...
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22 views
Simplest model for simulation of inter-arrival times with long-memory
I'm trying to model the inter-arrival times of stochastic point process that I've observed for the purpose of simulating it.
The Autocorrelation Function (ACF) of the inter-arrival times shows ...
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15 views
Area interaction model sufficient statistics calculation algorithm
I'm currently trying to write a simulation algorithm in Rcpp for a point process model which requires calculating the sufficient statistics for an Area interaction point process model. It entails a ...
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1answer
45 views
Maximum Pseudo-Likelihood estimator for soft-core point process
I am trying to fit a soft-core point process model on a set of point pattern using maximum pseudo-likelihood. I followed the instructions given in this paper by Baddeley and Turner
And here is the R-...
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51 views
Unexpected behavior in inhomogeneous Cross K Function (Kcross.inhom) [closed]
I am currently analyzing a point pattern in R using the "spatstat" package. I am comparing two different areas, therefore I made two plots for each area (first two plot-left-area1; second two plots-...
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13 views
Mutual info between discrete and continuous RV with history dependence
I am looking for literature references/measures to compute the mutual information between a continuous variable (time series) and a binary variable (a temporal sequence of 0's/1's). Briefly, a time ...
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1answer
85 views
Point Pattern Analysis: Assumptions for Hopkins-Skellam Index
I am currently analyzing a point pattern in R using the "spatstat" package. My analyses are primarily exploratory, as I do not have any strong reason to suspect either clustering or regularity, though ...
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15 views
Latent Point Process Inference
I need to perform inference on a point process, by which I mean I need a statistical model from which I can (at least) estimate likelihoods. The underlying process appears to have a latent structure, ...
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238 views
Point process - intensity function vs probability density function
Suppose we have a point process in $\mathbb{R}$ with intensity $\lambda(x)$. Then, for a given compact set ${ S}$ we have
$$\Lambda({ S})=\int_{\rm S} \lambda(x) \, dx,$$
where $\Lambda({ S})$ is ...
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1answer
326 views
Fit Hawkes process to 1d data using python package TICK
How can one fit the 1-dimensional Hawkes process with exponential kernel to the experimental 1d dataset (t1,t2,t3...tn) and check the goodness-of-fit
via tick python3 package?
I found on official ...
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20 views
Calculate L-function envelopes from a fitted model: Lest or Linhom?
I have fitted a model to a point pattern using INLA, and generated 1000 simulated pp from the posterior of this model. I want to use these samples to generate the L-function envelope for my data, and ...
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36 views
Does conditional intensity function of some model must perfectly match with data intensity if model is true?
I consider some emperical dataset characterized by a single parameter - the arrival times of events {$t_0,t_1,t_2,...,t_i$} as is commonly adopted for point processes. The Hawkes model is tested for ...
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33 views
Inconsistency of kernel intensity estimator
I have read that the kernel intensity estimator of a point process is not consistent, because the variance at any point is "of order 1".
What does he mean by "of order 1"? I would like to understand ...
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1answer
28 views
Create points pattern in R using spatstat package with specified number of points
Is it possible to generate points pattern with Poisson and Thomas process in R using spatstat package with specified number of points?
I had genereted Strauss point pattern using the Metropolis-...
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46 views
How to evaluate global and local effects in one model
I want to test the effect of elevation on the intensity of burrowing by gopher tortoises in flatwoods [a type of pine savanna characterized by both low (wet) and high (dry) areas]. However, in several ...
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20 views
R Time Series: how to estimate Time Until Given Total Is Reached?
I have historical car accident data by day, and want to estimate How Long (from a given "now" date) Until 100 Accidents Happen. The forecasting tools I've seen all are GIVEN a horizon parameter (how ...
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175 views
Mark correlation function in Spatstat
I have a conceptual question regarding the Mark Correlation function.
I have a 2D point pattern where each point has a numeric mark. I would like to test if there is high dependency of this mark ...
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0answers
26 views
Resource on Point Processes
I am not sure if this is the right place to ask and I'm new here.
I'm a Ph.D. student (electronics engineering) studying mainly on (multi) target tracking. The common approach is to use a Bayesian ...
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2answers
132 views
Is the Matérn covariance function associated with the Matérn cluster process?
This question follows on from something I couldn't figure out in this question.
Is there a relationship between the Matérn cluster process and Matérn covariance function beyond both being ...
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33 views
The probability of disc that fully overlaps discs in a Boolean model
In a example of Boolean model, points are scattered in the plane according to a homogeneous Poisson process of intensity $λ$. On each of these points a disc of fixed radius $r$ is placed.
Similar to ...
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1answer
125 views
Mean of nearest neighbour distance in a clustered distribution
What would be the expected value of distances to the nearest neighbor in a set of points in 2-dim space that have a clustered (not random) spatial distribution? If the distribution is random the ...
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0answers
39 views
ETAS model initial parameter determining
I am trying to fit a spatio-temporal epidemic type after schock model to an Earthquake catologue using ETAS package R. However, I do not know about it too much. Without good initial parameter set the ...
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0answers
15 views
Point process weakly modulated by an external signal
I would like to modulate the probability of firing of a point process by an external signal $x_{ext}(t) $, of varying amplitude and a specific frequency range (filtered Gaussian noise). The mean rate $...
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1answer
90 views
Hawkes processes: interpretation of maximum likelihood estimates disagreeing with moment estimator estimates?
So, I have some data.. and a parameterized Hawkes process which I estimate parameters for via maximum likelihood... the residuals ( the compensator aka the dual-predictable projection) are good in ...
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146 views
Distribution of distance to nearest (farthest) neighbour in normal data cloud
Here is an example of standard normal datasets (spherical, i.e. identity covariance matrices) in 1, 2, 3, 5, 10 dimensions, n=100 points. The picture shows observed ...
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1answer
396 views
Mean Nearest Neighbor test vs Nearest Neighbor function envelope test?
I am analyzing a point pattern using G (nearest neighbor cumulative distribution) function, followed up by the envelope tests and in the same time using Nearest Neighbor Index test (Clark Evans test )...
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1answer
80 views
Test for summary funtions: KS or envelope tests?
I want to study a point pattern using cumulative NND (Nearest Neighbor Distance) "G" function . The main task is to test H0: the point process is compatible with a null model (can be CSR (complete ...
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0answers
87 views
Extracting intervals out of an unevenly spaced time series
I am having a list of unevenly spaced data points - just occurrences, no values - and want to split them into intervals grouping occurrences, which are close together like so:
Currently I am ...
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1answer
86 views
All-to-All distances for point pattern analysis
I am new to point pattern analysis.
Trough my readings I haven't seen that any book would suggest to use All-to-All distances for point pattern analysis, but rather they talk about NND or other ...
3
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1answer
311 views
Stationarity assumption for a point process
as I understand stationarity of a point process implies that it is invariant under translation. Imagine one has numerous realizations of the same point process. Due to the nature of this process, it ...
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1answer
94 views
Analysis of spatial replicated patterns
I am new to spatstat.
I have a set of replicated patterns, I perform L test for each pattern and I pool the resulting statistic (using pool statistics in spatstat). Now I would like to perform a ...
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1answer
302 views
Averaging Ripley's K or L function for several samples
Would much appreciate to hear your opinion about the following strategy:
I have several samples of point patterns, witch are results from somw replicated experiment. The number of points and area of ...
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2answers
177 views
How to test change in rate of event occurrences?
Let x be the times (in whatever unit) at which a given event has been observed.
...
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1answer
218 views
Time Rescaling Theorem and Residual Analysis
Let $\mathcal{P}$ an homogeneous unit rate Poisson process.
It's conditional intensity function (star indicating conditioning on the history) can be written as
$$\lambda^*(t) = \lambda = 1$$
meaning ...
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1answer
82 views
Generating pattern of points from a pairwise interaction space point process
I have estimated the parameters of a non-homogeneous poisson space point process using Metropolis+gibbs from some observation data. I know:
$N$: Number of points inside my observation window
$\...
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1answer
154 views
Hawkes-Process for non binary events
I am currently using a univariate Hawkes-process for modeling the behaviour of agents in a social network. For example, the likelihood that a user will tweet in the next period is defined by the ...
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1answer
337 views
p-value for complete spatial randomness tests
I am using the Kolmogorov-Smirnov test to study the homogeneity of a point pattern in 3D using the distance transform to a structure as a covariate.
I am using the spatstat book, where it is ...
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0answers
43 views
Marked point process with spatial correlation (hard spheres with varying radii)
Problem: Given an arrangement of spheres of varying radii in a fixed domain , I am trying to simulate an arrangement of spheres in a domain of arbitrary size having the same statistics. The radii of ...
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0answers
62 views
The pdf of last interval of a Poisson process in $[0,T]$
Assume a Poisson point process with rate $\lambda$ in time $[0,T]$. Supoose $X$ is the random variable representing the time between the last arrival and $T$. What is the probability density function ...
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26 views
Sum of squared error and point process data
One standard distance measure applied in continuous data analysis is average sum of squared error. However, this method cannot be applied for point process data. And there is an alternative solution ...
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1answer
216 views
spatio-temporal density analysis of point patterns with lgcp
I am trying to use the R package lgcp to estimate density based on a point pattern over time. I follow the example given by the authors of the package in this article, but even the first step (copied ...
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1answer
66 views
Can data clustering algorithms be used to find the borders of an area in 2D space ?
If we have spatial points randomly distributed in 2D space, then we clustered those points according to some parameters, say location x,y. Can we use the same clustering algorithm and apply it on ...
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18 views
correlation measures for near-rotationally symmetric sets in the plane
I have two sets of data points $X, Y \subset \mathbb{R}^2$ what are the correlation measures we can use for such point processes?
Here the red points are a rotated copy of the blue points. Yet is ...
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0answers
70 views
poisson regression and discretization
I have data which is a natural fit for Poisson regression but I'm not sure how to correctly discretize the data into bins in a canonical or "best" way. One intuition is that I should use "small" ...
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0answers
46 views
Beeping boxes: survival analysis? times series?
I'm currently at a loss. I want to make a model that predicts when content providers aren't going to update anymore, but I'm having trouble finding a model that allows me to capture what I want. To ...
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611 views
Difference between time series prediction vs point process prediction
I am working on a problem of predicting event counts based on user history.
This is a classical time series analysis problem, and I used the ARIMA model: (wiki).
I also applied a Hawkes point process ...
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0answers
41 views
Good resource for p-thinning of a point process
Can you please tell me what is a good resource about p-thinning of a point process and then finding the distance between the original and obtained process? Something like the Kullback Leibler distance,...
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61 views
point patterns and line segment patterns
How could I attach points to the line segment pattern using R language Function
for example I have point pattern on linear network
and I have marked line segment pattern
I try to attach points in ...
