Getting helps

Entering data in R

Sometimes, you may need to work with very few values, hence it will be more time consuming to import from excel

In such cases, just enter those data in R

x<-c(2,5,4,6,8,2,3,10,3,13)

Similarly, combining different vectors

a<-c(40,50,41,24,52,48)          # entering data

b<-c(10,12,13,19,17,11)    # entering data

m<-cbind(a,b)                                   # to combine 2 vectors to matrix

m                                                           # to check the dataframe

d<-c(.1,.2,.4,.5,.8,.0)          # entering data

n<-rbind(a,b,d)                              # to combined 3 vectors to rows

n                                                                 # to check the dataframe

cbind= bind to columns

rbind= bind to rows

Making row and column

e<-c(1,3,3,4,1,2,5,2,5,1,5,15,13,14)

g<-matrix(c(e),nrow=7,ncol=2)

g                          # to check the matrix

f<-c(1,3,3,4,1,2,5,2,5,1,5,15,13,14,15,13,17)

h<-matrix(c(f),nr=7,nc=2)

h                          # to check the matrix, and see the error message displayed

BUT here, cbind will work, but eliminates exceeded data, try

k<-cbind(e,g,f)

k

Preparing data for R

Well shaped matrix will make your task ease

Good way of data tabulation when you have to compare to mediums that controls the density

Import data from demodata.xls, sheet 6 

read.table('clipboard',header=T)->density.block

attach(density.block)

mean(Medium.A)                  # mean density for medium A

mean(Medium.B)                  # mean density for medium B

read.table('clipboard',header=T)->density.stack

density.stack

attach(density.stack)

mean(Density)                   # this is for all values

mean(Density[Medium=='A'])      # mean for medium = A

mean(Density[Medium=='B'])      # mean for medium = B

Getting help in R

What you want to perform, search in Google

E.g. Calculating mode in R

Then look at the package name and function name

Install the package (if not installed already)

Then load the package (as did in previous practice)

Then find the command description file in R

Help (Mode)

or just

? Mode

The command to find help about a certain topic, for instance linear model:

help.search('linear model')

R will then list the functions that contain this topic.

It is easy to use the help function to discover the contents of library prackages. Here is how you find out about contents of the ”stats” library.

library (help=stats)

It will open a text file with detail of the library. It will give list of the commands and functions that are included in that library, and their brief description

And if you find any command or function you are looking for, look for detail of the command or function about how to use it, to find how to use just type

help(lm)  

or just  

?lm

It will open new window with some detail of the command or function

The window will guide you how to use it, and what are the elements that are required for the command, and some more

Typing help.start() opens a web browser with help information.

example(lm) will run any examples that are included in the help page for command lm.

demo(topic) runs demonstration code on topic lm: type demo() by itself to list all available demos

By default, R’s help system only provides information about functions that are in the base system and packages that you have loaded with library

??lm or help.search(lm) will list information related to topic available in the base system or in any extra installed packages

Crediting R

When we use R for any purpose, it should be cited, and to red the citation information

citation(package = "base", lib.loc = NULL, auto = NULL)

Citing any other package

citation(package = "prettyR", lib.loc = NULL, auto = NULL)

More under construction ......