txdat，  tydat，exdat这三条命令参数到底是什么意思呀，a p-variate data到底是什么数据类型？谢谢大家啦^_^

R中的说明如下：
npqreg {np}        R Documentation
Kernel Quantile Regression with Mixed Data Types

Description

npqreg computes a kernel quantile regression estimate of a one (1) dimensional dependent variable on p-variate explanatory data, given a set of evaluation points, training points (consisting of explanatory data and dependent data), and a bandwidth specification using the methods of Li and Racine (2008) and Li, Lin and Racine (2013). A bandwidth specification can be a condbandwidth object, or a bandwidth vector, bandwidth type and kernel type.

Usage

npqreg(bws, ...)

## S3 method for class 'formula'
npqreg(bws, data = NULL, newdata = NULL, ...)

## S3 method for class 'call'
npqreg(bws, ...)

## S3 method for class 'condbandwidth'
npqreg(bws,
       txdat = stop("training data 'txdat' missing"),
       tydat = stop("training data 'tydat' missing"),
       exdat,
       tau = 0.5,
       gradients = FALSE,
       ftol = 1.490116e-07,
       tol = 1.490116e-04,
       small = 1.490116e-05,
       itmax = 10000,
       lbc.dir = 0.5,
       dfc.dir = 3,
       cfac.dir = 2.5*(3.0-sqrt(5)),
       initc.dir = 1.0,
       lbd.dir = 0.1,
       hbd.dir = 1,
       dfac.dir = 0.25*(3.0-sqrt(5)),
       initd.dir = 1.0,
       ...)

## Default S3 method:
npqreg(bws, txdat, tydat, ...)

Arguments

txdat       
a p-variate data frame of explanatory data (training data) used to calculate the regression estimators. Defaults to the training data used to compute the bandwidth object.
tydat       
a one (1) dimensional numeric or integer vector of dependent data, each element i corresponding to each observation (row) i of txdat. Defaults to the training data used to compute the bandwidth object.
exdat       
a p-variate data frame of points on which the regression will be estimated (evaluation data). By default, evaluation takes place on the data provided by txdat.