Quickstarts

Small runnable scripts for the most common np, npRmpi, and crs entry points.

Keywords

quickstart, np, npRmpi, crs, examples, starter scripts

This page is the shortest route from “I need an example” to a small runnable script. The scripts below are the modern quickstarts in the gallery, and each block is pulled directly from the underlying source file.

Choose a starting point

If you want to…	Start here
fit a first kernel regression	np_regression_quickstart.R
use `nomad = TRUE` for a first local-polynomial fit	np_regression_nomad_quickstart.R
estimate a density with `np`	np_density_quickstart.R
estimate a distribution with `np`	np_distribution_quickstart.R
estimate a conditional density with `np`	np_conditional_density_quickstart.R
estimate a conditional distribution with `np`	np_conditional_distribution_quickstart.R
fit nonparametric conditional quantiles with `np`	np_quantile_quickstart.R
estimate a nonparametric copula	np_copula_quickstart.R
run a nonparametric classification / mode example	np_classification_quickstart.R
save a fitted curve with asymptotic intervals	np_plotting_quickstart.R
run an entropy/testing function with `np`	np_entropy_quickstart.R
fit a semiparametric model with `np`	np_semiparametric_quickstart.R
fit a nonparametric instrumental regression	np_instrumental_regression_quickstart.R
run a nonparametric significance test	np_significance_quickstart.R
run a model-specification test	np_specification_quickstart.R
use `npRmpi` interactively on macOS/Linux	nprmpi_session_quickstart.R
use the LP NOMAD shortcut after MPI initialization	nprmpi_session_nomad_quickstart.R
use `npRmpi` under `mpiexec`	nprmpi_attach_quickstart.R
use `npRmpi` with explicit broadcast control	nprmpi_profile_quickstart.R
fit a first spline model with `crs`	crs_quickstart.R
fit a spline instrumental-regression model	crs_iv_quickstart.R

`np` quickstarts

Kernel regression

Source file: np_regression_quickstart.R

## Minimal np regression example.
##
## The intended workflow is:
## 1. compute a bandwidth object,
## 2. fit the regression estimator,
## 3. inspect the result and a simple fitted curve.

library(np)
options(np.messages = FALSE)

data(cps71, package = "np")
dat <- cps71[, c("logwage", "age")]

## Select the bandwidth object, then fit the regression.
bw <- npregbw(logwage ~ age, data = dat, regtype = "ll", bwmethod = "cv.aic")
fit <- npreg(bws = bw, data = dat)

## Review the bandwidth choice and the fitted regression.
summary(bw)
summary(fit)

## Let the plot method handle the basic fitted-curve display.
plot(fit)

Automatic LP degree search

Source file: np_regression_nomad_quickstart.R

library(np)
data(cps71, package = "np")

## Use the shortest modern LP route: fit directly with nomad = TRUE.
fit_lp <- npreg(logwage ~ age, data = cps71, nomad = TRUE)

## Plot first, then inspect the fitted object in text form.
plot(fit_lp)
summary(fit_lp)

Density estimation

Source file: np_density_quickstart.R

## Minimal np density-estimation example.
##
## The intended workflow is:
## 1. compute a bandwidth object,
## 2. fit the density estimator,
## 3. inspect the result.

library(np)
options(np.messages = FALSE)

## Start with one variable so the density workflow is easy to read.
data(faithful, package = "datasets")
dat <- data.frame(waiting = faithful$waiting)

## Select the smoothing parameter, then fit the density.
bw <- npudensbw(~ waiting, data = dat, bwmethod = "cv.ml")
fhat <- npudens(bws = bw, data = dat)

## Review the bandwidth choice and the fitted density object.
summary(bw)
summary(fhat)

Distribution estimation

Source file: np_distribution_quickstart.R

## Minimal np distribution example.
##
## This mirrors the usual density workflow but targets the
## unconditional distribution function instead.

library(np)
options(np.messages = FALSE)

## Mirror the basic density setup, but target the distribution instead.
data(faithful, package = "datasets")
dat <- data.frame(waiting = faithful$waiting)

## Select the bandwidth, then fit the unconditional distribution.
bw <- npudistbw(~ waiting, data = dat, nmulti = 1)
Fhat <- npudist(bws = bw, data = dat)

## Review the smoothing choice and the fitted distribution object.
summary(bw)
summary(Fhat)

Conditional density estimation

Source file: np_conditional_density_quickstart.R

## Minimal np conditional-density example.
##
## This keeps the first run small enough to be practical while still
## showing the standard two-step workflow:
## 1. compute a bandwidth object,
## 2. fit the conditional-density estimator.

library(np)
options(np.messages = FALSE)

## Keep the first run small enough that the two-step workflow stays quick.
data(faithful, package = "datasets")
dat <- faithful[seq_len(120), c("eruptions", "waiting")]

## Select the bandwidth first, then fit the conditional density.
bw <- npcdensbw(eruptions ~ waiting, data = dat, nmulti = 1)
fhat <- npcdens(bws = bw, data = dat)

## Review both the smoothing choice and the fitted object.
summary(bw)
summary(fhat)

Conditional distribution estimation

Source file: np_conditional_distribution_quickstart.R

## Minimal np conditional-distribution example.
##
## This uses a small first run so the standard two-step workflow stays
## copyable and practical.

library(np)
options(np.messages = FALSE)

## Work on a smaller slice so the first run stays easy to inspect.
data(faithful, package = "datasets")
dat <- faithful[seq_len(120), c("eruptions", "waiting")]

## Select the bandwidth, then fit the conditional distribution.
bw <- npcdistbw(eruptions ~ waiting, data = dat, nmulti = 1)
Fhat <- npcdist(bws = bw, data = dat)

## Review the bandwidth object and the fitted distribution.
summary(bw)
summary(Fhat)

Conditional quantiles

Source file: np_quantile_quickstart.R

## Minimal np quantile-regression example.
##
## The key idea is to compute/select the conditional distribution once
## and then extract one or more quantiles from it.

library(np)
options(np.messages = FALSE)

## Keep the first quantile run compact and reproducible.
data(faithful, package = "datasets")
dat <- faithful[seq_len(120), c("eruptions", "waiting")]

## Build one conditional-distribution fit and request several quantiles.
qfit <- npqreg(eruptions ~ waiting,
               data = dat,
               tau = c(0.25, 0.50, 0.75),
               nmulti = 1)

## Review the bandwidth choice and one representative fitted quantile.
summary(qfit$bws)
summary(qfit)

## Plot the overlaid fitted quantile curves.
plot(qfit)

Copula estimation

Source file: np_copula_quickstart.R

## Minimal np copula example.
##
## This uses the direct formula interface and lets npcopula() build
## the corresponding marginal distribution bandwidth object internally.

library(np)
library(MASS)

set.seed(42)
n <- 1000
rho <- 0.95
Sigma <- matrix(c(1, rho, rho, 1), 2, 2)

## Simulate a simple bivariate sample with strong dependence.
dat <- as.data.frame(mvrnorm(n = n, mu = c(0, 0), Sigma = Sigma))
names(dat) <- c("x", "y")

## Let npcopula() create a small default probability grid.
copula_fit <- npcopula(~ x + y, data = dat, neval = 20)

## Inspect the fitted copula object and the retained bandwidth object.
summary(copula_fit)
summary(attr(copula_fit, "bws"))

Classification and conditional mode

Source file: np_classification_quickstart.R

## Minimal np classification / conditional-mode example.
##
## This keeps the first run compact while still showing the basic
## nonparametric classification route.

library(np)
data(birthwt, package = "MASS")

## Class the discrete fields the way the estimator expects them.
birthwt$low <- factor(birthwt$low)
birthwt$smoke <- factor(birthwt$smoke)
birthwt$race <- factor(birthwt$race)

## Fit the conditional-mode classifier on a small practical formula.
fit <- npconmode(low ~ smoke + race + age + lwt, data = birthwt, nmulti = 1)

## Inspect the fitted object, then the implied confusion matrix.
summary(fit)
fit$confusion.matrix

Plotting and asymptotic intervals

Source file: np_plotting_quickstart.R

## Minimal np plotting and interval example.
##
## This fits a simple local-linear model and then shows the
## modern bootstrap plotting route with all interval/band types.

library(np)
options(np.messages = FALSE)

data(cps71, package = "np")

## Fit a simple local-linear regression object.
model.ll <- npreg(logwage ~ age, regtype = "ll", data = cps71)

## Save one example plot so the script works in non-interactive sessions too.
plot_path <- file.path(tempdir(), "np_plotting_quickstart.png")
png(plot_path, width = 700, height = 500)
plot(model.ll,
  errors = "bootstrap",
  bootstrap = "inid",
  band = "all")
dev.off()

## Report where the rendered image landed.
cat("Saved plot to:", plot_path, "\n")

Entropy and testing

Source file: np_entropy_quickstart.R

## Minimal np entropy/testing example.
##
## This uses the univariate density-equality test because it is a
## compact, fast first run.

library(np)
options(np.messages = FALSE)

## Generate two simple samples so the test output is easy to interpret.
set.seed(1234)
n <- 300
x <- rnorm(n)
y <- rnorm(n)

## Run a compact first test without bootstrap overhead.
test_out <- npunitest(x, y, bootstrap = FALSE)

## Inspect the test summary.
summary(test_out)

Semiparametric models

Source file: np_semiparametric_quickstart.R

## Minimal np semiparametric example.
##
## This uses a partially linear model because it is the clearest
## lightweight entry point into the semiparametric family.

library(np)
options(np.messages = FALSE)

## Build a small partially linear data-generating setup.
set.seed(42)
n <- 200
x1 <- rnorm(n)
z <- runif(n)
y <- 1 + 2 * x1 + sin(2 * pi * z) + rnorm(n, sd = 0.2)
dat <- data.frame(y, x1, z)

## Fit the partially linear model.
fit <- npplreg(y ~ x1 | z, data = dat)

## Inspect the fitted semiparametric object.
summary(fit)

Instrumental regression

Source file: np_instrumental_regression_quickstart.R

## Minimal np instrumental-regression example.
##
## This mirrors the basic one-endogenous-regressor setup used in the
## package demos while keeping the first run compact.

library(np)

## Build a small one-endogenous-regressor example with one instrument.
set.seed(42)
n <- 80
v <- rnorm(n, sd = 0.27)
eps <- rnorm(n, sd = 0.05)
u <- -0.5 * v + eps
w <- rnorm(n)
z <- 0.2 * w + v
y <- z^2 + u

## Fit the nonparametric IV regression.
fit_iv <- npregiv(y = y, z = z, w = w, method = "Tikhonov", nmulti = 1)

## Inspect the fitted IV object.
summary(fit_iv)

Significance testing

Source file: np_significance_quickstart.R

## Minimal np significance-testing example.
##
## The idea is to fit a model with one irrelevant regressor and then
## ask whether the nonparametric significance test detects that.

library(np)
options(np.messages = FALSE)

## Generate one relevant and one irrelevant regressor on purpose.
set.seed(42)
n <- 200
z <- factor(rbinom(n, 1, 0.5))
x1 <- rnorm(n)
x2 <- runif(n, -2, 2)
y <- x1 + x2 + rnorm(n)
dat <- data.frame(z, x1, x2, y)

## Fit the model before asking the significance question.
fit <- npreg(y ~ z + x1 + x2,
  regtype = "ll",
  bwmethod = "cv.aic",
  data = dat)

## Test the fitted object and inspect both summaries.
test_out <- npsigtest(fit)

summary(fit)
summary(test_out)

Model specification testing

Source file: np_specification_quickstart.R

## Minimal np model-specification test example.
##
## The idea is to fit a simple linear model to nonlinear data and then
## ask whether the parametric specification looks too restrictive.

library(np)
options(np.messages = FALSE)

## Simulate nonlinear data, then fit an intentionally simple linear model.
set.seed(42)
n <- 120
x <- runif(n, -2, 2)
y <- x + x^2 + rnorm(n, sd = 0.25)

model_ols <- lm(y ~ x, x = TRUE, y = TRUE)
X <- data.frame(x = x)

## Compare the parametric model to the nonparametric alternative.
test_out <- npcmstest(model = model_ols,
  xdat = X,
  ydat = y,
  nmulti = 1)

## Inspect both the linear fit and the specification test.
summary(model_ols)
summary(test_out)

`npRmpi` quickstarts

Session / spawn mode

Source file: nprmpi_session_quickstart.R

## Minimal modern npRmpi example.
##
## The intended workflow is:
## 1. initialize MPI once in session/spawn mode,
## 2. write ordinary np-style code,
## 3. quit cleanly at the end.

library(npRmpi)

## Initialize once, then work as if this were an ordinary np script.
npRmpi.init(nslaves = 1)

set.seed(1)
x <- runif(200)
y <- sin(2 * pi * x) + rnorm(200, sd = 0.2)
dat <- data.frame(y, x)

## Fit the bandwidth and regression objects.
bw <- npregbw(y ~ x, regtype = "ll", bwmethod = "cv.ls", data = dat)
fit <- npreg(bws = bw, data = dat)

## Review the objects, plot the fit, then exit cleanly.
summary(bw)
summary(fit)

plot(fit)

npRmpi.quit()

Session mode with nomad = TRUE

Source file: nprmpi_session_nomad_quickstart.R

## Minimal modern npRmpi NOMAD example.
##
## The intended workflow is:
## 1. initialize MPI once,
## 2. use the same nomad = TRUE shortcut available in np,
## 3. inspect the normalized shortcut metadata,
## 4. quit cleanly at the end.

if (!requireNamespace("crs", quietly = TRUE)) {
  stop("This quickstart uses nomad = TRUE, which requires the 'crs' package ",
    "for NOMAD degree search. Install it with install.packages('crs').")
}

library(npRmpi)

## Initialize once, then write ordinary np-style code.
npRmpi.init(nslaves = 1)

set.seed(7)
n <- 120
x <- runif(n, -1, 1)
y <- x + 0.4 * x^2 + rnorm(n, sd = 0.18)
dat <- data.frame(y, x)

## Fit the LP shortcut and inspect the normalized metadata.
fit <- npreg(y ~ x, data = dat, nomad = TRUE, degree.max = 2L, nmulti = 1L)

fit$bws$nomad.shortcut
summary(fit)

## Plot the fitted object before quitting cleanly.
plot(fit)

npRmpi.quit()

Attach mode

Source file: nprmpi_attach_quickstart.R

## Minimal attach-mode npRmpi example.
##
## Launch with a pre-created MPI world, for example:
##   mpiexec -env R_PROFILE_USER "" -env R_PROFILE "" -n 2 \
##     Rscript --no-save nprmpi_attach_quickstart.R

library(npRmpi)

## Initialize under an already-created MPI world.
npRmpi.init(mode = "attach")

if (mpi.comm.rank(0L) == 0L) {
  ## Build the data and fit on the coordinator rank.
  set.seed(1)
  x <- runif(200)
  y <- sin(2 * pi * x) + rnorm(200, sd = 0.2)
  dat <- data.frame(y, x)

  bw <- npregbw(y ~ x, regtype = "ll", bwmethod = "cv.ls", data = dat)
  fit <- npreg(bws = bw, data = dat)

  ## Inspect the fitted objects, then shut down cleanly.
  summary(bw)
  summary(fit)

  npRmpi.quit(mode = "attach")
}

Profile / manual-broadcast mode

Source file: nprmpi_profile_quickstart.R

## Minimal profile/manual-broadcast npRmpi example.
##
## Launch with an explicit profile source, for example:
##   RPROFILE=$(Rscript --no-save -e 'cat(system.file("Rprofile", package="npRmpi"))')
##   mpiexec -env R_PROFILE_USER "$RPROFILE" -env R_PROFILE "" -n 2 \
##     Rscript --no-save nprmpi_profile_quickstart.R

## Initialize the workers through the profile route.
invisible(mpi.bcast.cmd(np.mpi.initialize(), caller.execute = TRUE))

## Build the data once on the caller and broadcast it.
set.seed(1)
x <- runif(200)
y <- sin(2 * pi * x) + rnorm(200, sd = 0.2)
dat <- data.frame(y, x)

invisible(mpi.bcast.Robj2slave(dat))

## Fit the bandwidth and regression objects on the workers.
invisible(mpi.bcast.cmd(bw <- npregbw(y ~ x, regtype = "ll", bwmethod = "cv.ls", data = dat),
  caller.execute = TRUE))

invisible(mpi.bcast.cmd(fit <- npreg(bws = bw, data = dat),
  caller.execute = TRUE))

## Inspect the results, then stop the MPI workers.
summary(bw)
summary(fit)

invisible(mpi.bcast.cmd(mpi.quit(), caller.execute = TRUE))

`crs` quickstart

Spline regression

Source file: crs_quickstart.R

## Minimal crs spline-regression example.
##
## This is the smallest useful workflow:
## 1. fit a spline model,
## 2. inspect the summary,
## 3. optionally move on to plotting or tighter search control.

library(crs)
options(crs.messages = FALSE)

## Generate a simple nonlinear surface with two predictors.
set.seed(42)
n <- 250
x1 <- runif(n)
x2 <- runif(n)
y <- sin(2 * pi * x1) + x2 + rnorm(n, sd = 0.2)
dat <- data.frame(y, x1, x2)

## Fit the spline model and inspect the summary.
fit <- crs(y ~ x1 + x2, data = dat)

summary(fit)

Instrumental spline regression

Source file: crs_iv_quickstart.R

## Minimal crs instrumental-regression example.
##
## This is a compact first run for spline-based IV estimation.

library(crs)

## Build a small IV example with one endogenous regressor and one instrument.
set.seed(42)
n <- 100
v <- rnorm(n, sd = 0.27)
eps <- rnorm(n, sd = 0.05)
u <- -0.5 * v + eps
w <- rnorm(n)
z <- 0.2 * w + v
y <- z^2 + u

## Fit the spline IV model.
fit_iv <- crsiv(y = y,
  z = z,
  w = w,
  method = "Landweber-Fridman",
  cv = "exhaustive",
  nmulti = 1,
  cv.threshold = 0)

## Inspect the fitted IV object.
summary(fit_iv)

Where to go next

Code Catalog for the broader script library
Kernel Methods for np
Density, Distribution, Quantiles for conditional densities, distributions, and quantiles
MPI and Large Data for npRmpi
Splines for crs

Choose a starting point

np quickstarts

npRmpi quickstarts

crs quickstart

Where to go next

`np` quickstarts

`npRmpi` quickstarts

`crs` quickstart