w4.R

# 周次：w4
# 任務：操作向量
# 姓名：李凱翔
# 日期：2021年2月26日

### 課本練習
# 題組
# 1. 我們有一個文字向量 `weekdays` 是星期一到星期五，
weekdays <-c("monday","tuesday","wednesday","thursday","friday")
weekdays <-c("星期一","星期二","星期三","星期四","星期五")
# 請您將最喜歡的週五（Happy Friday）從這個向量中
# 用索引值選出來並且指派給 `favorite_day`
favorite_day <- weekdays[5]
favorite_day 

## [1] "星期五"

# 2. 請您利用判斷運算子將最藍的週一（Blue Monday）從這個向量中剔除後
# 將剩餘的日子指派給 `without_monday`
weekdays <-c("monday","tuesday","wednesday","thursday","friday")
not_blue_monday <- weekdays != "monday"
not_blue_monday 

## [1] FALSE  TRUE  TRUE  TRUE  TRUE

without_monday  <- weekdays[not_blue_monday]
without_monday

## [1] "tuesday"   "wednesday" "thursday"  "friday"

without_monday  <- weekdays[-1]
without_monday

## [1] "tuesday"   "wednesday" "thursday"  "friday"

without_monday  <- weekdays[2:5]
without_monday

## [1] "tuesday"   "wednesday" "thursday"  "friday"

### 進階練習
# 題組
# 使用內建的資料集iris來回答下列問題
# 1. 認識iris資料集(https://zh.wikipedia.org/wiki/%E5%AE%89%E5%BE%B7%E6%A3%AE%E9%B8%A2%E5%B0%BE%E8%8A%B1%E5%8D%89%E6%95%B0%E6%8D%AE%E9%9B%86)

# 2. 請問第1-5個樣本的花瓣長度為何?

# 3. 第50-60個樣本的花瓣寬度為何?

# 4. 請創建一個iris_setosa的子集，品種均為setosa

# 5. 請創建一個iris_5子集，花萼長度>5