| Title: | Estimate Causal Polytree from Data | 
| Version: | 0.0.1 | 
| Maintainer: | Sourav Chatterjee <souravc@stanford.edu> | 
| Description: | Given a data matrix with rows representing data vectors and columns representing variables, produces a directed polytree for the underlying causal structure. Based on the algorithm developed in Chatterjee and Vidyasagar (2022) <doi:10.48550/arXiv.2209.07028>. The method is fully nonparametric, making no use of linearity assumptions, and especially useful when the number of variables is large. | 
| License: | MIT + file LICENSE | 
| Encoding: | UTF-8 | 
| RoxygenNote: | 7.3.1 | 
| Imports: | FOCI, igraph | 
| NeedsCompilation: | no | 
| Packaged: | 2024-03-24 02:47:21 UTC; sourav | 
| Author: | Sourav Chatterjee | 
| Repository: | CRAN | 
| Date/Publication: | 2024-03-25 19:10:12 UTC | 
This is the function that computes the skeletion tree from data. The input is a matrix x whose rows are the data vectors. The sample size n is the number of rows. The number of variables p is the number of columns The function outputs the skeleton tree g.
Description
This is the function that computes the skeletion tree from data. The input is a matrix x whose rows are the data vectors. The sample size n is the number of rows. The number of variables p is the number of columns The function outputs the skeleton tree g.
Usage
condeptree(x)
Arguments
| x | The input data matrix. | 
Creates an outgoing tree from a given undirected treee.
Description
Creates an outgoing tree from a given undirected treee.
Usage
outgoing(tree, dir_tree = NULL, a = NULL, b = 1)
Arguments
| tree | Input tree, undirected. | 
| dir_tree | Directionalities that must be present. | 
| a | The node being inspected. | 
| b | The neighbor being inspected. | 
Causal Polytree Estimation
Description
Estimates directed causal polytree from data, using algorithm developed in Chatterjee and Vidyasagar (2022).
Usage
polytree(x)
Arguments
| x | Data matrix, whose rows are i.i.d. data vectors generated from the model. | 
Value
A directed polytree estimated from the input data, as an igraph object.
References
Sourav Chatterjee and Mathukumalli Vidyasagar (2022). Estimating large causal polytrees from small samples. Available at https://arxiv.org/abs/2209.07028
Examples
p <- 10
n <- 200
x <- matrix(nrow = n, ncol = p)
for (i in 1:n) {
   x[i,1] = rnorm(1)
   for (j in 2:p) {
      x[i,j] = (x[i,j-1] + rnorm(1))/sqrt(2)
   }
}
p <- polytree(x)
This function computes the xi correlation coefficient.
Description
This function computes the xi correlation coefficient.
Usage
xicorln(xvec, yvec)
Arguments
| xvec | The vector of x values. | 
| yvec | The vector of y values. |