Python入門學習筆記_1
阿新 • • 發佈：2018-12-13
基礎一
賦值
a = b = c = d = 10
e記法
a = 0.000000025
b = 2.5e-8
print(a, "\n")
print(b)
變數型別轉換
a = "520"
b = int(a)
b
a = 5.99
b = int(a)
b
a = "520"
b = float(a)
b
b = str(5e+19)
b
a = "520"
type(a)
a = "打野"
isinstance(a, str)
運算子
+, -, *, /, %, **, //
#//地板除，取商
print(10 // 4)
print(3.0 // 2)
#冪運算
print(3 ** 3)
# 同時得到商和餘數 2
1.0
27
(1, 4)
邏輯操作符
True and False
True or False
not True
3 < 4 < 5
條件分支
a = 0
if True:
a = 1;
else:
a = 2;
a
while迴圈
a = 0
while a < 8:
a += 1
輸入
temp = input("Enter a number:")
print(temp)
匯入包
import keyword
print( keyword.kwlist )
斷言（assert）
assert for迴圈
str = "Daye"
for ch in str:
print(ch, end = " ")
member = ["Tom", "Nancy", "Tom", "Bill"]
for each in member:
print(each, len(each))
range(5)
list(range(5))
for each in range(2, 9):
print(each)
for each in range(1, 10, 2):
print(each)
基礎二
字串
- 分片([start : end : step])
str = 'Daye is a boy'
print(str[ : 13 : 2])
print(str[-3 : : 1]) #倒數第三位到最後一位
Dy saby
boy
- split()分割
str2 = 'I am twenty-two years old'
print(str2.split())
str3 = 'apple,pear,banana,bean'
print(str3.split(','))
['I', 'am', 'twenty-two', 'years', 'old']
['apple', 'pear', 'banana', 'bean']
- join()合併
crypto_list = ['yellow', 'blue', 'black', 'white']
crypto_string = ','.join(crypto_list)
print(crypto_string)
yellow,blue,black,white
- startswith()、endswith()
poem = 'All that doth flow we cannot liquid name that'
print("startswith = ", poem.startswith('All'))
print("endswith = ", poem.endswith('name'))
startswith = True
endswith = False
- find()、rfind()
print(poem.find('that'))
print(poem.rfind('that'))#最後一次出現的位置
4
41
- count()
poem.count('that')
2
- isalnum()是否全為數字或者字母
print("pome ", poem.isalnum())
poem2 = 'abcd'
print("pome2 ", poem2.isalnum())
pome False
pome2 True
- strip()將字串尾部的規定字元刪除
setup = 'a duck goes into a bar...'
setup.strip('.')
'a duck goes into a bar'
- 大小寫操作
- capitalize()[將字串首字母大寫]
setup.capitalize()
'A duck goes into a bar...'
- title()[將所有單詞的開頭字母大寫]
setup.title()
'A Duck Goes Into A Bar...'
- upper()[將所有字母變成大寫]
setup.upper()
'A DUCK GOES INTO A BAR...'
- lower()[將所有字母變成小寫]
setup.lower()
'a duck goes into a bar...'
- swapcase()[將所有字母大小寫轉換]
setup.swapcase()
'A DUCK GOES INTO A BAR...'
- 格式排版函式
- center()、ljust()、rjust()
print(setup.center(30))
print(setup.ljust(30))
print(setup.rjust(30))
a duck goes into a bar...
a duck goes into a bar...
a duck goes into a bar...
- replace()
setup.replace('duck', 'marmoset', 100)#100表示最多修改次數
'a marmoset goes into a bar...'
列表、元組、字典與集合
列表
- 普通列表
member = ["Tom", "Nancy", "Tony", "Bill"]
print(member)
number = [1, 2, 3, 4, 5]
print(number)
['Tom', 'Nancy', 'Tony', 'Bill']
[1, 2, 3, 4, 5]
- 混合列表
mex = [1, "Daye", 3.14, [1, 2, 3]]
print(mex)
- 空列表
empty = []
empty
向列表新增元素
- append()方法
member.append("Linda")
member
- extend()方法
member.extend(['Dear', 'Pmr'])
member
- insert()方法
member.insert(1, 'Zqy')
member
從列表中刪除元素
- remove()方法
member.remove('Tom')
member
- del方法
del member[0] #如果不加下標，會整個列表刪除
member
['Nancy', 'Bill', 'Linda', 'Dear', 'Pmr']
- pop()方法[有返回值]
member.pop()
'Pmr'
name = member.pop()
name
'Dear'
member.pop(1)
member
['Nancy', 'Linda']
列表分片(Slice)
print("member = ", member)
print("1:3 = ", member[1:3])
print(":3 = ", member[:3])
print(": = ", member[:])
print(": : 2= ", member[: : 2])
member = ['Tom', 'Nancy', 'Tony', 'Bill']
1:3 = ['Nancy', 'Tony']
:3 = ['Tom', 'Nancy', 'Tony']
: = ['Tom', 'Nancy', 'Tony', 'Bill']
: : 2= ['Tom', 'Tony']
列表常用操作符
- 比較操作符
list1 = [123, 456]
list2 = [234, 123]
print("list1 > list2 = ", list1 > list2) #第一個決定大小，如果相等比較下一個，以此類推
list3 = [123, 456]
print("list1 < list2) and (list1 == list3) = ", (list1 < list2) and (list1 == list3))
list1 > list2 = False
list1 < list2) and (list1 == list3) = True
- 連線、重複操作符
#list4 = list1 + list2 建議不要使用，使用extend
list3 * 3
list3 *= 3
print(list3)
[123, 456, 123, 456, 123, 456]
- 成員關係操作符
123 in list3
"123" not in list3
True
list5 = [123, ["Daye", "Pmr"], 456]
print('Daye' in list5)
print('Daye' in list5[1])
print(list5[1][1])
False
True
Pmr
- 內建函式
print(dir(list))
['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__hash__', '__iadd__', '__imul__', '__init__', '__init_subclass__', '__iter__', '__le__', '__len__', '__lt__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__reversed__', '__rmul__', '__setattr__', '__setitem__', '__sizeof__', '__str__', '__subclasshook__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']
- count()
print(list3.count(123))
81
- index(member, startSite, endSite)
print(list3)
print(list3.index(123, 3, 10)) #3-10內，123出現的位置
[123, 456, 123, 456, 123, 456]
4
- reverse()
list3.reverse()
print(list3)
[456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123, 456, 123]
- sort()
list6 = [4, 5, 6, 1, 10, 2]
list6.sort()
print(list6)
list6.sort(reverse = True)
print(list6)
list6_1 = sorted(list6)
print(list6_1)
[1, 2, 4, 5, 6, 10]
[10, 6, 5, 4, 2, 1]
[1, 2, 4, 5, 6, 10]
- 分片拷貝**（注意）**
list7 = list6
print("list7 = ", list7)
list8 = list6[:]
print("list8 = ", list8)
list9 = list6.copy()
print("list9 = ", list9)
#list6.sort()
list6.sort()
print("反向排序後：")
print("list7 = ", list7)
print("list8 = ", list8)
print("list9 = ", list9)
list7 = [10, 6, 5, 4, 2, 1]
list8 = [10, 6, 5, 4, 2, 1]
list9 = [10, 6, 5, 4, 2, 1]
反向排序後：
list7 = [1, 2, 4, 5, 6, 10]
list8 = [10, 6, 5, 4, 2, 1]
list9 = [10, 6, 5, 4, 2, 1]
- join()
marxes = ['yellow', 'black', 'white']
print(','.join(marxes))
yellow,black,white
元組
建立元組
- 普通建立
empty_tutle = ()
print(empty_tutle)
one_marx = 'Groucho',#如果裡面只有一個元素，需要在末尾加上','逗號
print(one_marx)
marx_tuple = ('yellow', 'black', 'white')
print(marx_tuple)
x, y, z = marx_tuple #可直接將元組賦值給多個變數，變數數量 = 元組元素個數
print(x, " ", y, " ", z)
()
('Groucho',)
('yellow', 'black', 'white')
yellow black white
- 利用tuple()函式建立元組
marx_list = ['yellow', 'black', 'white'] #建立一個列表
tuple(marx_list)
('yellow', 'black', 'white')
字典
建立字典
- 普通建立
empty_dict = {}
print(empty_dict)
bierce = {
"day" : "A period of twenty-four hours",
"positive" : "Mistaken at the top of one's voice",
"misfortune" : "The kind of fortune that never misses"
}
print(bierce)
{}
{'day': 'A period of twenty-four hours', 'positive': "Mistaken at the top of one's voice", 'misfortune': 'The kind of fortune that never misses'}
- 利用dict()函式轉換為字典
lol = [['a', 'b'], ['c', 'd'], ['e', 'f']] #列表+子列表
print("列表+子列表: ", dict(lol))
lot = [('a', 'b'), ('c', 'd'), ('e', 'f')] #列表+元組
print("列表+元組: ", dict(lot))
tol = (['a', 'b'], ['c', 'd'], ['e', 'f']) #元組+列表
print("元組+列表: ", dict(tol))
los = ['ab', 'cd', 'ef'] #列表+雙字元
print("列表+雙字元: ", dict(los))
tos = ('ab', 'cd', 'ef') #元組+雙字元
print("元組+雙字元: ", dict(tos))
列表+子列表: {'a': 'b', 'c': 'd', 'e': 'f'}
列表+元組: {'a': 'b', 'c': 'd', 'e': 'f'}
元組+列表: {'a': 'b', 'c': 'd', 'e': 'f'}
列表+雙字元: {'a': 'b', 'c': 'd', 'e': 'f'}
元組+雙字元: {'a': 'b', 'c': 'd', 'e': 'f'}
使用[key]新增或修改元素
some_pythons = {
'A':'Tony',
'B':'Nancy',
'C':'Tom',
'D':'Linda',
'E':'Terry'
}
print(some_pythons)
some_pythons['E'] = 'Anny'
some_pythons['F'] = 'Lucy'
print(some_pythons)
{'A': 'Tony', 'B': 'Nancy', 'C': 'Tom', 'D': 'Linda', 'E': 'Terry'}
{'A': 'Tony', 'B': 'Nancy', 'C': 'Tom', 'D': 'Linda', 'E': 'Anny', 'F': 'Lucy'}
update()合併字典
other = {'G':'Vance', 'H':'Case'}
some_pythons.update(other)
print(some_pythons)
{'A': 'Tony', 'B': 'Nancy', 'C': 'Tom', 'D': 'Linda', 'E': 'Anny', 'F': 'Lucy', 'G': 'Vance', 'H': 'Case'}
del刪除元素
del some_pythons['H']
some_pythons
{'A': 'Tony',
'B': 'Nancy',
'C': 'Tom',
'D': 'Linda',
'E': 'Anny',
'F': 'Lucy',
'G': 'Vance'}
clear()刪除所有元素
other.clear()
other
{}
獲取元素
print(some_pythons['A'])
print(some_pythons.get('B'))
Tony
Nancy
dict_keys(['A', 'B', 'C', 'D', 'E', 'F', 'G'])
獲取鍵和值
print(some_pythons.keys()) #取得鍵
print(some_pythons.values()) #取得值
print(some_pythons.items()) #取得鍵和值
dict_keys(['A', 'B', 'C', 'D', 'E', 'F', 'G'])
dict_values(['Tony', 'Nancy', 'Tom', 'Linda', 'Anny', 'Lucy', 'Vance'])
dict_items([('A', 'Tony'), ('B', 'Nancy'), ('C', 'Tom'), ('D', 'Linda'), ('E', 'Anny'), ('F', 'Lucy'), ('G', 'Vance')])
集合
建立集合
empty_set = set()
print(empty_set)
even_number = {0, 1, 3, 5, 7}
print(even_number)
print(set('letters')) #值不可重複，同樣用列表、元組、字典都可以建立集合。需注意的是字典轉為集合，只有鍵
set()
{0, 1, 3, 5, 7}
{'l', 'r', 's', 'e', 't'}
合併及運算子
a = {1, 2}
b = {2, 3}
- 交集（共有元素）
print("a & b = ", a & b)
print("intersection(): ", a.intersection(b))
a & b = {2}
intersection(): {2}
- 並集（合併但不重複）
print("a | b = ", a | b)
a | b = {1, 2, 3}
- 差集（出現在第一個單不出現在第二個）
print("a - b", a - b)
a - b {1}
- 異或集（僅在兩個集合中出現一次）
print("a ^ b", a ^ b)
print("symmetric_difference(): ", a.symmetric_difference(b))
a ^ b {1, 3}
symmetric_difference(): {1, 3}
- 判斷是否為子集
print("a <= b", a <= b)
print("issubset(): ", a.issubset(b))
a <= b False
issubset(): False
- 判斷是否為真子集
print("a < b", a < b)
print("issuperset(): ", a.issuperset(b))
a < b False
issuperset(): False