Common Functions

Question 1

getwd()

Answer 1

Get working directory

Question 2

setwd(“x”)

x is path to working directory

Answer 2

Set working directory

Question 3

install.packages(“x”)

x is package name

Answer 3

Installs package

Question 4

library(x)

x is package name

Answer 4

Load a package

Question 5

print(x)

x is a variable

Answer 5

Display contents of a variable

Question 6

nrow(df)

df is a data frame

Answer 6

Determine the number of rows in a data frame or matrix

Question 7

ncol(df)

df is a data frame

Answer 7

Determine the number of columns in a data frame or matrix

Question 8

rm(x)

x is a variable

Answer 8

Delete a variable from your programming environment

Question 9

read_csv(“data.csv”)

data.csv is a file

Answer 9

read a CSV (comma-separated value) file and create a data frame

Question 10

write.csv(“output.csv”)

output.csv is a file

Answer 10

exports the data frame as a csv file

Question 10

sd(df$Age)

Age is a column in the data frame

Answer 10

Calculate the standard deviation

Question 11

help(package = “x”)

x is a package name

Answer 11

find help for a package

Question 12

mean(df$Age)

Age is a column in a data frame

Answer 12

calculate the average

Question 13

summary(df)

df is a data frame

Answer 13

provide a summary of descriptive stats for each variable in a data frame

Question 14

head(df)

df is a data frame

Answer 14

View the first few rows of a data frame or matrix

Question 15

tail(df)

df is a data frame

Answer 15

View the last few rows of a data frame or matrix

Question 16

str(df)

df is a data frame

Answer 16

Display a structure of a data frame or matrix