funsAijmat {nnspat} | R Documentation |
Aij matrices for computation of Moments of Cuzick and Edwards T_k
Test statistic
Description
Two functions: aij.mat
and aij.nonzero
.
The function aij.mat
yields the A=(a_{ij}(k))
matrix where a_{ij}(k) = 1
if z_j
is among the k
NNs of z_i
and 0 otherwise due to Tango (2007).
This matrix is useful in calculation of the moments of Cuzick-Edwards T_k
tests.
The function aij.nonzero
keeps only nonzero entries, i.e., row and column entries where
in each row, for the entry (r_1,c_1)
r_1
is the row entry and c_1
is the column entry. Rows are from
1 to n, which stands for the data point or observation, and column entries are from 1 to k
, where k
is specifying
the number of k
NNs (of each observation) considered. This function saves in storage memory, but needs to be
carefully unfolded in the functions to represent the actual the A
matrix.
See also (Tango (2007)).
Usage
aij.mat(dat, k, ...)
aij.nonzero(dat, k, ...)
Arguments
dat |
The data set in one or higher dimensions, each row corresponds to a data point. |
k |
Integer specifying the number of NNs (of subject |
... |
are for further arguments, such as |
Value
The function aij.mat
returns the A_{ij}
matrix for computation of moments of Cuzick and Edwards T_k
Test statistic while the function aij.nonzero
returns the (locations of the) non-zero entries in the A_{ij}
matrix
Author(s)
Elvan Ceyhan
References
Tango T (2007). “A class of multiplicity adjusted tests for spatial clustering based on case-control point data.” Biometrics, 63, 119-127.
See Also
Examples
n<-20 #or try sample(1:20,1)
Y<-matrix(runif(3*n),ncol=3)
k<-3 #try also 2,3
Aij<-aij.mat(Y,k)
Aij
Aij2<-aij.mat(Y,k,method="max")
range(Aij,Aij2)
apply(Aij,2,sum) #row sums of Aij
aij.nonzero(Y,k)
aij.nonzero(Y,k,method="max")