---
title: HW2
tags: dataframe
---
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# `HW2重點小整理：`
> format( ): 對字串進⾏格式化
> ex：
> ```python
> print ('{0} study in {1}'.format("John","FCU"))
> ```

### **寫下第⼀隻Python程式**

print ("This is my first Python program")

### **假設你⽤每股80元買進⼀張(1000股)台灣的上市股票，⼀個⽉以後以87賣出，請問獲利是多少？投報率是多少？**

nBuy=80
nSell=87

nProfit=(87-80)*1000
nRate=nProfit/(nBuy*1000)
print ('獲利 :{0}元'.format(nProfit))
print ('投報率 :{0:.2f}%'.format(nRate*100))

> {0:.2f}第0個變數，⼩數點後第2位
> <span class="green">查找 % 的意思</span>
> -> 百分比的意思

### **假設有⼀字串(string)如下：s ='I am a fourth grade student at FCU’印出這個字串的長度為何**

s ='I am a fourth grade student at FCU'
print('字串的長度為 {0}'.format(len(s)))

> 使⽤==len( )函數==，可以知道字串的長度
> 使⽤==lower( )函數==，可以將字串中所有字元符號變成⼩寫
> ex:
> ```python
> strA = "Hello, World!"
> print(strA.lower())

### **假設有⼀串列(list)如下：list_fruit= ['banana','orange', 'melon', ‘apple', ‘mango',‘cherry', 'kiwi']印出這個串列中的項⽬ 'melon', 'apple', 'mango'**

list_fruit= ['banana','orange', 'melon', 'apple','mango','cherry','kiwi']
print (list_fruit[2:5])

> list (串列)
> ```python
> lst=[1,2,3,4,5,6]
> lst #[1,2,3,4,5,6]
> lst[:] #[1,2,3,4,5,6]
> lst[0] #the first item 1
> lst[-1] #the last item 6
> lst[0:] #[1,2,3,4,5,6]
> lst[0:-1] #[1,2,3,4,5]
> lst[1:-2] #[2,3,4]

### **假設某學⽣的課程分數使⽤字典(dict)表⽰如下：score = {'homework':92,'mid-term':85,'final-term':92}，⽽作業分數佔50%, 期中考30%, 期末考20%, 請印出這位學⽣學期末成績**

score = {'homework':92,'mid-term':85,'final-term':87}
final=score['homework']*0.5 + score['mid-term']*0.3 +
score['final-term']*0.2
print('期末成績：{0:.1f}分'.format(final))

> 使⽤key['model']取得字典的value
> {0:.1f}第0個變數，⼩數點後第1位