R code Cheatsheet

set working directory

setwd(“/Users/anupo/biostats_lab)

to load dataset

name = read.csv(“/Users/anupo/biostats/nameoffile”)

to see number of total rows and columns

dim(data)

vector for rows and columns

[rows, columns]

give an example?

subset data to only include certain columns or rows

hint: use vector integers

data = data[“row 1”, “row2”, “row3”, “column1”, “column2”, “column3”]

number of columns

ncol(data)

number of rows

nrow(data)

to rename columns/rows

names(data)=c(“rename”)

to print out

print(paste(“total number of variable”, ncol(nyc))

to call specific column/row

data$column/row

in columns, there are numbers representing a certain string. what do you do to change the numbers to a string?

call the row or column, call factor, call the levels, and use the labels function in a c() function to change

data$column = factor(data$column, levels = c(1,2,3,4,5), labels = c(“name”, “name”)

create a table

table_name= table(data$column)

print(table_name)

rounding integers in a columns/row

call the column or row, use round function, and specify number of digits

data$row = round(data$row, digits = 0)

create a vector

v =c(1,2,3)

combine functions, collect elements into a vector

c()

tapply