LAB - R Commands

c()

Combines values into a vector

dim()

Finds dimension of an object

head()

Returns the first part of a vector, matrix, table, data frame, or function

length()

Finds length of vector

names()

Find the names of the variables in a data frame

max()

Finds the maximum of the input values

min()

Finds the minimum of the input values

mean()

Finds the mean of the input values

read.csv()

Reads a file in table format and creates a data frame from it

sum()

Finds the sum of the input values

View()

View data frame in a spreadsheet-style format

Vector

Is an ordered collection of numbers, words, and generally ‘objects’ in R. Use c() function

Why is it important to add comments

Helps clarify code to person reading it; use the # symbol

hist()

Creates a histogram

par()

Sets graphics parameters

par(mfrow)

Sets the mfrow graphics parameter to control the layout of subplots in a graph

barplot()

makes a bar graph

table()

Tabulates counts of categorical data

subset()

Selects subset of vectors, matrices, or dataframes that meet certain consitions

prop.table()

Tabulates proportion of occurrence of categorical data

data.frame()

Creates a data frame

boxplot(y ~ x)

Make a boxplot of the distribution of the numerical variable y, grouped by the levels of the categorical variable, x

tapply (y, x, FUN=f)

Split the data y into subsets according to the grouping x variables, computes summary statistics f for each

View()

Views a data frame in the script window

mean()

Calculates the average for a numerical vector

median()

Calculates the median for a numerical vector

sd()

Calculates the standard deviation for a numerical vector

plot(x,y)

plots a graph, where x is the independent variable and y is the dependent variable. If you don’t specify the type, it only plots points

For plot(x,y), type = “l”

gives line graph without showing dots

For plot(x,y), type = “o”

gives line graph with both showing dots and lines

table()

Creates a table of counts

prop.table()

Creates a table of proportions

dbinom()

Calculates a binomial probability

pbinom()

Calculates a cumulative binomial probability

round(,)

Rounds the values in its first argument to the specified number of decimal places (default 0)

chisq.test()

Performs a chi square test

spineplot()

Creates a mosaic plot

t()

Transposes a matrix

dpois(count, lambda)

Density value for the Poisson distribution with mean

pchisq(q,df)

Cumulative distribution dunction for the chi-squared distribution with df degrees of freedom

sum(x)

Computes the sum of all the values present in its argument x

qchisq(p,df)

Quantile function for the chi-squared distribution with df degrees of freedom