Intro to Data Science - HW 1

Copyright Jeffrey Stanton, Jeffrey Saltz, and Jasmina Tacheva

# Enter your name here: Kyle Chouinard 

Attribution statement: (choose only one and delete the rest)

# 2. I did this homework with help from the book and the professor and these Internet sources:https://www.youtube.com/watch?v=o_ldRKmgvHo

Define a variable:

x <- 5

Define the following vectors, which represent the population (in thousands) and number of colleges in each of the five counties in Central New York (CNY) – Cayuga, Cortland, Madison, Onondaga, and Oswego, in this order:

population <- c(80, 49, 73, 467, 122)
colleges <- c(2, 2, 3, 9, 2)

Part 1: Calculating statistics using R

1. Show the number of observations in the population vector with the length() function:

length(population)

## [1] 5

#Population length is 5

2. Show the number of observations in the colleges vector with the length() function:

length(colleges)

## [1] 5

#Colleges length is 5

3. Calculate the average CNY population using the mean() function:

mean(population)

## [1] 158.2

#Mean population is 158.2

4. Calculate the average number of colleges in CNY using the mean() function:

mean(colleges)

## [1] 3.6

#Mean colleges is 3.6

5. Calculate the total CNY population using the sum() function:

sum(population)

## [1] 791

#Sum of population is 791

6. Calculate the total number of colleges in CNY using the sum() function:

sum(colleges)

## [1] 18

#Sum of colleges is 18

7. Calculate the average CNY population again, this time using the results from steps A & E:

sum(population)/length(population)

## [1] 158.2

#The average population is 158.2

8. Calculate the average number of colleges in CNY again, this time using the results from steps B & F:

sum(colleges)/length(colleges)

## [1] 3.6

#Average number of colleges is 3.6

Part 2: Using the max/min and range functions in {r}

1. How many colleges does the county with most colleges have? Hint: Use the max() function:

max(colleges)

## [1] 9

#Onondaga County has the most colleges

10. What is the population of the least populous county in CNY? Hint: Use the min() function:

min(population)

## [1] 49

#Cortland has the lowest population

11. Display the populations of the least populous and most populous county in the dataset together. Hint: Use the range() function:

range(population)

## [1]  49 467

#Cortland is the least populous, Onondaga is the most

Part 3: Vector Math

12. Create a new vector called extraPop, which is the current population of a county + 50 (each county has 50,000 more people):

extrapop <- (colleges+50)

13. Calculate the average of extraPop:

mean(extrapop)

## [1] 53.6

#Mean of ExtraPop is 53.6

14. In a variable called bigCounties, store all the population numbers from the original population vector which are greater than 120 (using subsetting in R):

BigCoutnies <- population[c(4,5)]

15. Report the length of bigCounties:

length(BigCoutnies)

## [1] 2

#Length of BigCounties is 2