--- title: "Homework 1 Solutions" output: html_document --- ```{r setup, include=FALSE} knitr::opts_chunk\$set(echo = TRUE) ``` # Ch. 2, Q1 ```{r} x <- c("economics", "econometrics", "ECON 4750") library(stringr) str_length(x) ``` # Ch. 2, Q3 **Part a** ```{r} fibonacci <- function(n) { # handle cases where n=1 or 2 if (n == 1) { return(0) } if (n==2) { return(1) } # main code fib_seq <- c(0,1) for (i in 3:n) { fib_seq[i] <- fib_seq[i-1] + fib_seq[i-2] } fib_seq[n] } ``` ```{r} fibonacci(5) fibonacci(8) ``` **Part b** ```{r} alt_seq <- function(a,b,n) { # handle cases where n=1 or 2 if (n == 1) { return(a) } if (n==2) { return(b) } # main code this_seq <- c(a,b) for (i in 3:n) { this_seq[i] <- this_seq[i-1] + this_seq[i-2] } this_seq[n] } ``` ```{r} alt_seq(3,7,4) ``` # Ch. 2, Q5 **Part a** ```{r} nrow(iris) ``` **Part b** ```{r} mean(iris\$Sepal.Length) ``` **Part c** ```{r} mean(subset(iris, Species=="setosa")\$Sepal.Width) ``` **Part d** ```{r} sorted_iris <- iris[order(iris\$Petal.Length),] sorted_iris[1:10,] ```