As part of Learn Data analysis using R tutorials. This post explains how to use help in R or how to find help inside R.
There is extensive online help in the R system, the best starting point is to run the function help.start(). This will launch a local page inside your browser with links to the R manuals, R FAQ, a search engine and other links.
Help function
Now let’s see how to get help on a particular function. In the R Console, the function help can be used to see the help file of a specific function.
Example: Getting help for mean function in R
Use the following command to get help on mean function.
help(mean)
You will get the following Output explaining arguments available in function and examples on how to use the function.
Arithmetic Mean
Description:
Generic function for the (trimmed) arithmetic mean.
Usage:
mean(x, ...)
## Default S3 method:
mean(x, trim = 0, na.rm = FALSE, ...)
Arguments:
x: An R object. Currently there are methods for numeric/logical
vectors and date, date-time and time interval objects.
Complex vectors are allowed for ‘trim = 0’, only.
trim: the fraction (0 to 0.5) of observations to be trimmed from
each end of ‘x’ before the mean is computed. Values of trim
outside that range are taken as the nearest endpoint.
na.rm: a logical value indicating whether ‘NA’ values should be
stripped before the computation proceeds.
...: further arguments passed to or from other methods.
Value:
If ‘trim’ is zero (the default), the arithmetic mean of the values
in ‘x’ is computed, as a numeric or complex vector of length one.
If ‘x’ is not logical (coerced to numeric), numeric (including
integer) or complex, ‘NA_real_’ is returned, with a warning.
If ‘trim’ is non-zero, a symmetrically trimmed mean is computed
with a fraction of ‘trim’ observations deleted from each end
before the mean is computed.
References:
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) _The New S
Language_. Wadsworth & Brooks/Cole.
See Also:
‘weighted.mean’, ‘mean.POSIXct’, ‘colMeans’ for row and column
means.
Examples:
x <- c(0:10, 50)
xm <- mean(x)
c(xm, mean(x, trim = 0.10))
help.search Function
Use the function help.search to list help files that contain a certain word. Use the following command to get help on word “linear regression”.
help.search("linear regression")
You will get the following Output
Help files with alias or concept or title matching ‘linear regression’ using fuzzy matching: datasets::anscombe Anscombe's Quartet of 'Identical' Simple Linear Regressions KernSmooth::dpill Select a Bandwidth for Local Linear Regression MASS::area Adaptive Numerical Integration Concepts: Non-linear Regression MASS::rms.curv Relative Curvature Measures for Non-Linear Regression Concepts: Non-linear Regression stats::D Symbolic and Algorithmic Derivatives of Simple Expressions Concepts: Non-linear Regression stats::getInitial Get Initial Parameter Estimates Concepts: Non-linear Regression stats::nlm Non-Linear Minimization Concepts: Non-linear Regression stats::nls Nonlinear Least Squares Concepts: Non-linear Regression stats::nls.control Control the Iterations in nls Concepts: Non-linear Regression stats::optim General-purpose Optimization Concepts: Non-linear Regression stats::plot.profile.nls Plot a profile.nls Object Concepts: Non-linear Regression stats::predict.nls Predicting from Nonlinear Least Squares Fits Concepts: Non-linear Regression stats::profile.nls Method for Profiling nls Objects Concepts: Non-linear Regression stats::vcov Calculate Variance-Covariance Matrix for a Fitted Model Object Concepts: Non-linear Regression Type ’help(FOO, package = PKG)’ to inspect entry ’FOO(PKG) TITLE’.
Each package in R comes up with manual which can be accessed from R or can be read from CRAN.
