📖研習進度
list)list是由『有序(ordered)』的元素(element)構成。[]建立listx = [True, 1, 1.0, '1', 1 + 0j, "100", ['a', 'b', 'c']]
x## [True, 1, 1.0, '1', (1+0j), '100', ['a', 'b', 'c']]type(x)## <class 'list'>len(x) # 取得list元素個數## 7y = [2, 3, [4, 5]]
len(y) # 只計算第1層元素的個數## 3list('NCCU')## ['N', 'C', 'C', 'U']list(range(-4, 4))## [-4, -3, -2, -1, 0, 1, 2, 3]l2 = [1, 2, [3, 4]]
l3 = [5, 6, [7, 8]]
l2 + l3 # list的拼接(concatenation)## [1, 2, [3, 4], 5, 6, [7, 8]]l2 * 3 # list的重複## [1, 2, [3, 4], 1, 2, [3, 4], 1, 2, [3, 4]]matrix = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
matrix## [[1, 2, 3], [4, 5, 6], [7, 8, 9]]matrix[1]## [4, 5, 6]matrix[1][1]## 5[n]取值x = ["first", "second", "third", "fourth"]
x[0]## 'first'x[2]## 'third'x[-1] # 取最後一個位置## 'fourth'x[-2] # 取得倒數第二個位置## 'third'提取多個元素時採切片(slicing)
[index1:index2]：代表指定從index1至index2之間(不包括index2)的元素
L = ['NCCU', 'MoneyBanking', 'QF', 'students', 'class']
L[0:2]## ['NCCU', 'MoneyBanking']L[1:3]## ['MoneyBanking', 'QF']L[1:-1]## ['MoneyBanking', 'QF', 'students']L[-2:-1]## ['students']L[:2] # 只️取前2個元素## ['NCCU', 'MoneyBanking']L[2:] # 不取前2個元素## ['QF', 'students', 'class']
x = L[:]
x## ['NCCU', 'MoneyBanking', 'QF', 'students', 'class']x == L## Truex is L## FalseL[-1:2]## []x = [1, 2, 3]
x[1:2] = [8, 9] # 長度可變：insertion
x## [1, 8, 9, 3]x = [1, 2, 3]
x[1:1] = [8, 9] # 長度可變：insertion, replace nothing
x## [1, 8, 9, 2, 3]x = [1, 2, 3, 4]
x[len(x):] = [5, 6, 7]
x## [1, 2, 3, 4, 5, 6, 7]x[:0] = [-1, 0]
x## [-1, 0, 1, 2, 3, 4, 5, 6, 7]x[1:-1] = [] # 移除list內多個元素
x## [-1, 7]# R code:
# L <- list(1, 2, 3)
# L[1] <- list(8, 9)
# 被替換的項目不是替換值長度的倍數L = [1]
L[:0] = [2, 3, 4] # insert all at 0
L## [2, 3, 4, 1]L[len(L):] = [5, 6, 7] # insert all at len(L)
L## [2, 3, 4, 1, 5, 6, 7]L.extend([8, 9, 10]) # insert all at end, by method
L## [2, 3, 4, 1, 5, 6, 7, 8, 9, 10]list更多的操作append()方法與extend()方法L = ['eat', 'more', 'SPAM']
L.append('please')
L## ['eat', 'more', 'SPAM', 'please']x = [1, 2, 3, 4]
y = [5, 6, 7]
x.append(y)
x## [1, 2, 3, 4, [5, 6, 7]]x = [1, 2, 3, 4]
y = [5, 6, 7]
x.extend(y) # 請與L.extend() method 比較
x
## [1, 2, 3, 4, 5, 6, 7]insert()方法：可在兩元素之間或list最前端加入新元素list.insert(n, 新元素)等同於 list[n:n] = [新元素]x = [1, 2, 3]
x.insert(2, 'Hello') # 在第2個元素之前插入新元素
x## [1, 2, 'Hello', 3]x.insert(0, 'start') # 在第0個元素之前插入新元素
x## ['start', 1, 2, 'Hello', 3]x.insert(-1, 'Hi')
x## ['start', 1, 2, 'Hello', 'Hi', 3]list的排序list擁有內建sort方法可供排序，為原地排序(sort in place)，會改變原本的list內容
可迭代(iterable)的物件不一定有內建sort方法， 如tuple、set與dict的key值。
另有「通用函數(universal function)」: sorted()，不做原地修改，回傳一個排序完成的list
數字與字串無法比較
L.sort()
L## ['SPAM', 'eat', 'more', 'please']L.append(['Chen']) # 請與L.extend() method 比較
L
# L.sort()
# TypeError: '<' not supported between instances of 'list' and 'str'
#
# Detailed traceback:
# File "<string>", line 1, in <module>## ['SPAM', 'eat', 'more', 'please', ['Chen']]L = ['abc', 'ABD', 'aBe']
L.sort()
L## ['ABD', 'aBe', 'abc']L = ['abc', 'ABD', 'aBe']
L.sort(key = str.lower)
L## ['abc', 'ABD', 'aBe']L = ['abc', 'ABD', 'aBe']
L.sort(key = str.lower, reverse = True)
L## ['aBe', 'ABD', 'abc']x = [[3, 5], [2, 9], [2, 3], [4, 1], [3,2], [2, 9, 1], [3]]
x.sort()
x## [[2, 3], [2, 9], [2, 9, 1], [3], [3, 2], [3, 5], [4, 1]]x.sort(reverse=True)
x## [[4, 1], [3, 5], [3, 2], [3], [2, 9, 1], [2, 9], [2, 3]]L = ["abf", "ABe", "aBD"]
L## ['abf', 'ABe', 'aBD']L.sort(key=str.lower)
L## ['aBD', 'ABe', 'abf']def compare_num_of_chars(string1):
return len(string1)
def compare_num_of_chars(string1):
return len(string1)
word_list = ['Python', 'is', 'better', 'than', 'C']
word_list.sort()
print(word_list)## ['C', 'Python', 'better', 'is', 'than']word_list = ['Python', 'is', 'better', 'than', 'C']
word_list.sort(key=compare_num_of_chars)
print(word_list)## ['C', 'is', 'than', 'Python', 'better']['C', 'is', 'than', 'Python', 'better']
## ['C', 'is', 'than', 'Python', 'better']x = [4, 3, 1, 2]
sorted(x)## [1, 2, 3, 4]del可使程式碼可讀性提高x = [1, 2, 4, 5]
del x[1]
x## [1, 4, 5]x = ["a", "c", 1, 2, 3, 4]
del x[:2]
x## [1, 2, 3, 4]remove()x = [1, 2, 3, 4, 3, ]
x.remove(3)
x## [1, 2, 4, 3]x.remove(3)
x
# x.remove(3)
# x
# ValueError: list.remove(x): x not in list## [1, 2, 4]reverse()x = [1, 2, 3, 4]
x.reverse()
x## [4, 3, 2, 1]L = ['spam', 'eggs', 'ham']
L.index('eggs')
# L.index('egg')
# ValueError: 'egg' is not in list
#
# Detailed traceback:
# File "<string>", line 1, in <module>## 1L.insert(1, 'toast')
L## ['spam', 'toast', 'eggs', 'ham']L.remove('eggs')
L## ['spam', 'toast', 'ham']L.pop(1) # delete by position## 'toast'L## ['spam', 'ham']['1', '2', '1', '1', '3'].count('1') # number of occurences## 3L = ['spam', 'eggs', 'ham', 'toast']
del L[0]
L## ['eggs', 'ham', 'toast']del L[1:3]
L## ['eggs']3 in [3, 1, 4, 5]## True3 not in [2, 1, 5, 2]## Truez = [2, 1, 2 ] + [3, 4, 5]
z## [2, 1, 2, 3, 4, 5]z = [None] * 5
z## [None, None, None, None, None]z = [4, 1, 2] * 2
z## [4, 1, 2, 4, 1, 2]min(z)## 1max(z)## 4L = [1, 2,]
L.extend([3, 4, 5])
L## [1, 2, 3, 4, 5]L.pop() # # Delete and return last item (by default: −1)## 5L## [1, 2, 3, 4]L.reverse()
L## [4, 3, 2, 1]reversed(L)## <list_reverseiterator object at 0x7f997f62efa0>list(reversed(L))## [1, 2, 3, 4]for x in [1, 2, 3]:
print(x, end="\n")
## 1
## 2
## 3res = []
for c in "SPAM":
res.append(c * 4)
res## ['SSSS', 'PPPP', 'AAAA', 'MMMM'][c * 4 for c in "SPAM"]## ['SSSS', 'PPPP', 'AAAA', 'MMMM']list(map(abs, [-1, -2, 0, 1, 2])) # map a function across a seqence## [1, 2, 0, 1, 2]list(map(len, [[1, 2, 3], [2, 1], [5, 5, 5, 5]]))## [3, 2, 4]m = [[0, 1, 2], [10, 11, 12], [20, 21, 22]]
m## [[0, 1, 2], [10, 11, 12], [20, 21, 22]]m[0]## [0, 1, 2]m[0][1]## 1m[2][2]## 22nested = [0]
original = [nested, 1]
original
## [[0], 1]nested[0] = 'zero'
original## [['zero'], 1]original[0][0] = 0
nested## [0]original
## [[0], 1]nested = [2] # 將nested改設定為另一個list, 則之間的連結則會被破壞
original## [[0], 1]淺層複製不會將第二層以上的list複製一份，而是參考到原list
original = [[0], 1]
shallow = original[:] # 淺層複製(shallow copy)
import copy
deep = copy.deepcopy(original)
shallow[1] = 2
shallow## [[0], 2]original## [[0], 1]shallow[0][0] = 'zero'
original
## [['zero'], 1]deep[0][0] = 5
deep## [[5], 1]original
## [['zero'], 1]tuple)與list類似，但tuple只能被建立而不能被修改(不可變，immutable)，故可當dict的鍵值(key)
與list類似，在Python中被視為有順序(ordered)的『序列(sequence)』
其中，str、list與tuple在Python中皆視為有順序的『序列(sequence)』
也可採[]進行取值與切片
+與＊亦可使用
import random
t0 = () # empty tuple
t0## ()type(t0)## <class 'tuple'>t1 = (1, 2, 2, random.gauss(10, 2))
t1## (1, 2, 2, 7.724059356332024)type(t1)## <class 'tuple'>t2 = 2, 4, 8, 1
t2## (2, 4, 8, 1)type(t2)## <class 'tuple'>max(t2)## 8t3 = 3,
type(t3)## <class 'tuple'>5 in (4, 1, 2, 4, 5, 2)## True(one, two, three, four) = (1, 2, 3, 4) # 自動打包(packing)後自動解包(unpacking)，同時指定4個變數值
one## 1two## 2x, y, z, p = 1, 2, 3, 4 # 會將所有逗號,分隔的資料打包為tuple
z, p## (3, 4)v1, v2, v3 = [1, 2, 3]
v1## 1w1, w2, w3 = 'abc'
w2
# q1, q2 = 'ABC' # 多重指定變數值時，兩邊數量要一樣多
# ValueError: too many values to unpack (expected 2)
#
# Detailed traceback:
# File "<string>", line 1, in <module>## 'b'a = 100
b = 200
temp = a
a = b
b = temp
a, b## (200, 100)a = 100
b = 200
a, b = b, a
a, b## (200, 100)*自動解包
*的標記的元素會將所有多餘的項目當作list來接收# a, b, c = 1, 2, 3, 4
# ValueError: too many values to unpack (expected 3)
a, b, *c = (1, 2, 3, 4) #
a## 1b## 2c## [3, 4]a, *b, c = (1, 2, 3, 4)
a## 1b## [2, 3]c## 4*a, b, c = (1, 2, 3, 4)
a## [1, 2]b## 3c## 4a,b,c## ([1, 2], 3, 4)a, b, c, d, *e = (1, 2, 3, 4)
a## 1b## 2c## 3e## []x = [1, 2, 3, 4, 5]
a, b, *_ = x
a## 1b## 2_ # 常用來代表用不到的資料## [3, 4, 5]list與tuple的轉換list()函數將任何序列型資料轉為list。而tuple()函數則轉為tuple。list((1, 2, 3, 4))## [1, 2, 3, 4]tuple([1, 2, 3, 4])## (1, 2, 3, 4)list('NCCU')## ['N', 'C', 'C', 'U']tuple('Money and Banking')## ('M', 'o', 'n', 'e', 'y', ' ', 'a', 'n', 'd', ' ', 'B', 'a', 'n', 'k', 'i', 'n', 'g')set)set代表無順序的資料所構成(list與tuple之元素則有順序意義)
set中重複的資料會被自動刪除不計，可保持元素唯一性
值得注意的是，set中的元素須為『不可變的資料(immutable)』，故int、float、str、與tuple可作為set的元素。而list、dict與set本身則不行。
當任務的重點為判斷一群資料是否包含某個物件，而不重視順序時，則可使用set型別
因set中的元素沒有順序，故無法使用索引[n]或切片來存取，且+與*也無法使用
x = {1, 2, 1, 3, 3, 1, 2, 4}
x## {1, 2, 3, 4}type(x)## <class 'set'>x = set([1, 2, 1, 3, 3, 1, 2, 4])
x## {1, 2, 3, 4}type(x)## <class 'set'>x.add(6)
x## {1, 2, 3, 4, 6}x.remove(2)
x## {1, 3, 4, 6}3 in x## True5 in x## Falsex = {1, 2, 1, 2, 1, 2}
y = set([1, 7, 7, 8, 9])
x## {1, 2}y## {8, 1, 9, 7}x | y # 聯集## {1, 2, 7, 8, 9}x & y # 交集## {1}x ^ y # Symmetric Difference (XOR): 只屬於其中一個集合，且不屬於另一個集合之元素所形成的集合## {2, 7, 8, 9}x - y # 差集## {2}x1 = {'foo', 'bar', 'baz'}
x1.issubset({'foo', 'bar', 'baz', 'qux', 'quux'})## Truex1 <= {'foo', 'bar', 'baz', 'qux', 'quux'}## Truex2 = {'baz', 'qux', 'quux'}
x1 <= x2 ## Falsev = {"a", "e", "i", "o", "u"}
v.add("x")
v## {'e', 'x', 'i', 'u', 'o', 'a'}v.discard("z") # 與v.remove()不同，當欲移除之元素不存在時，則不會出現錯誤訊息
v## {'e', 'x', 'i', 'u', 'o', 'a'}letters = set("alice")
letters## {'e', 'i', 'a', 'c', 'l'}letters.intersection(v)## {'e', 'i', 'a'}letters.union(v)## {'e', 'x', 'i', 'a', 'c', 'o', 'l', 'u'}letters.difference(v)## {'l', 'c'}letters.symmetric_difference(v)## {'x', 'c', 'u', 'o', 'l'}s = {"a", "e"}
s.issubset(letters)## Trueletters.issuperset(s)## Trueletters.isdisjoint(s)## False因set無法成為另一個set的元素(因set為可變的型別)，故Python提供frozenset型別解決上述問題
frozenset為不可變型別
x = set([1, 2, 3, 1, 3, 5])
z = frozenset(x)
type(x)## <class 'set'>type(z)## <class 'frozenset'># z.add(6)
# AttributeError: 'frozenset' object has no attribute 'add'
#
# Detailed traceback:
# File "<string>", line 1, in <module>x.add(z)
x## {1, 2, 3, 5, frozenset({1, 2, 3, 5})}len(x)## 5dict)int』、 『str』、或其他Python不可變物件，且必須為唯一的dict來實作dictages = {'Mary':13, 'John': 14, 'Tony':13}
type(ages)## <class 'dict'>ages## {'Mary': 13, 'John': 14, 'Tony': 13}'Mary' in ages## Truex = {}
x## {}type(x)## <class 'dict'>x[0] = 'NCCU' # 此0是當作key，並非當作索引用
x[1] = 'Money and Banking'
x## {0: 'NCCU', 1: 'Money and Banking'}x[1]## 'Money and Banking'len(x)## 2y = []
type(y)
# y[0] = 'NCCU' # 指定一個不存在的索引值0，值得注意的是：R允許這個操作
# IndexError: list assignment index out of range
#
# Detailed traceback:
# File "<string>", line 1, in <module>## <class 'list'># R code:
l <- list()
l[1] <- "NCCU"
l## [[1]]
## [1] "NCCU"dict其他操作english_to_french = {'red': 'rouge', 'blue': 'bleu', 'green': 'vert'}
len(english_to_french)## 3list(english_to_french.keys())## ['red', 'blue', 'green']list(english_to_french.values())## ['rouge', 'bleu', 'vert']list(english_to_french.items())## [('red', 'rouge'), ('blue', 'bleu'), ('green', 'vert')]del english_to_french['green']
list(english_to_french.items())## [('red', 'rouge'), ('blue', 'bleu')]'red' in english_to_french## True'orange' in english_to_french## Falseenglish_to_french.get('blue', 'No translation')## 'bleu'english_to_french.get('chartreuse', 'No translation')## 'No translation'english_to_french.setdefault('chartreuse', 'No translation') # 找不到該值時，會新增 鍵:值## 'No translation'x = {0: 'zero', 1: 'one'}
y = x.copy()
y## {0: 'zero', 1: 'one'}z = {1: 'One', 2: 'Two'}
x = {0: 'zero', 1: 'one'}
x.update(z)
x## {0: 'zero', 1: 'One', 2: 'Two'}str)補充字串為不可變「字元」序列：字串為字元依照順序組成
故可進行取值與切片
x = 'Goodbye\n!' # \n:換行跳脫字元(escape character)
x## 'Goodbye\n!'len(x)## 9print(x) # print函數自動在字串尾端添加換行跳脫字元 ## Goodbye
## !print("HIHI") # print函數自動在字串尾端添加換行跳脫字元 ## HIHIy = 'Goodbye!'
len(y)## 8print(y)## Goodbye!z = 'a\n\tb'
z## 'a\n\tb'print(z)## a
## bprint("abc\n") # 2次換行## abcprint("abc\n", end='') # 1次換行## abcx = "Hello" + "World"
x## 'HelloWorld'x = "Hello" "World" # Python會將空白相隔的字串連接在一起
x## 'HelloWorld'split()與join()：切割與連結字串join()函數用於連結字串
雖+也可以用於連結字串，但+用於連結字串時，會建立新字串。故建立大量字串時，會產生很多無用的字串物件，程式碼效率會變差
" ".join(["join", "puts", "spaces", "between", "elements"])## 'join puts spaces between elements'"::".join(["Separated", "with", "colons"])## 'Separated::with::colons'"".join(["Separated", "by", "nothing"])## 'Separatedbynothing'split()會將字串分割為字串list，其預設以空白字元(whitespace)切割字串
空白字元包含空格、換行、定位等字元
x = "You\t\t can have tabs\t\n \t and newlines \n\n mixed in"
x.split()## ['You', 'can', 'have', 'tabs', 'and', 'newlines', 'mixed', 'in']x = "Mississippi"
x.split("ss")## ['Mi', 'i', 'ippi']x = 'a b c d'
x.split(' ', 1)## ['a', 'b c d']x.split(' ', 2)## ['a', 'b', 'c d']x.split(' ', 100)## ['a', 'b', 'c', 'd']float('123.456')
# float('xxyy')
# ValueError: could not convert string to float: 'xxyy'## 123.456int('3333')
# int('123.456')
# ValueError: invalid literal for int() with base 10: '123.456'## 3333int('10000', 8)## 4096int('101', 2)## 5int('ff', 16)
# int('123456', 6)
# ValueError: invalid literal for int() with base 6: '123456'## 255strip()、lstrip()、rstrip()移除開頭或結尾處的多餘空白x = " Hello, World\t\t "
x.strip()## 'Hello, World'x.lstrip() # 移除左的空白## 'Hello, World\t\t ''Hello, World\t\t '## 'Hello, World\t\t 'x.rstrip() # 移除左的空白
## ' Hello, World'import string
string.whitespace # 查詢被Python視為空白的字元## ' \t\n\r\x0b\x0c'x = "www.python.org"
x.strip("w") ## '.python.org'x.strip("gor") # 移除所有g, o, r字元 ## 'www.python.'x.strip(".gorw") # 移除所有 ., g, o, r, w字元
## 'python'demo = " Demo Example " # 移除所有的空白
demo.replace(" ", "") ## 'DemoExample'x = "123"
x.isdigit() ## Truex.isalpha() ## Falsex = "MM"
x.islower() ## Falsex.isupper()
## Trueimport string
string.ascii_letters## 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ'string.ascii_uppercase## 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'string.ascii_lowercase## 'abcdefghijklmnopqrstuvwxyz'string.digits
## '0123456789'in operatorx = "The string"
"str" in x## True"sTr" in x## False"e s" in x## Truefind(string, start, end)x = "Mississippi"
x.find("ss")## 2x.find("zz") # 找不到傳回-1## -1x = "Mississippi"
x.find("s")## 2x.find("s",2) # 從索引2開始尋找## 2x.find("s",4) # 從索引4開始尋找## 5x.find("s",4,5) ## 從索引4開始尋找，並在索引5之前結束## -1x.find("ss", 3)## 5x.find("ss", 0, 3)## -1rfind()：從字串的結尾向開頭進行搜尋，並傳回搜尋文字最後出現的索引位置x = "Mississippi"
x.rfind("ss")## 5index()與rindex()：index()與rindex()分別與find()和rfind()相同，但index()與rindex()找不到文字時，不會回傳-1而是引發ValueError例外錯誤x = "Mississippi"
# x.index("zz")
# ValueError: substring not foundcount()x = "Mississippi"
x.count("ss")## 2x.count("s")## 4startswith()與endswith()x = "Mississippi"
x.startswith("Miss")## Truex.startswith("Mist")## Falsex.endswith("pi")## Truex.endswith("p")
## False雖然字串為不可變資料型態，但字串物件仍提供幾個method可對該字串進行操作，並回傳一個修改後的新字串
replace()
x = "Mississippi"
x.replace("ss", "+++")## 'Mi+++i+++ippi'maketrans()、translate()x = "~x ^ (y % z)"
table = x.maketrans("~^()", "!&[]") # 組成一個字元參照表
type(table) # 按照參照表table來替換字元## <class 'dict'>x.translate(table)## '!x & [y % z]'list來修改字串text = "Hello, World"
wordList = list(text)
wordList[6:] = []
wordList.reverse()
text = "".join(wordList)
print(text) ## ,olleHrepr()與str()將物件轉換為字串表示repr()傳回的字串是給Python程式讀取(formal string representation)，可透過此字串重建原始物件
str()傳回的字串是給人看的(informal string representation)，可讀性比較高
許多情況之下，repr()與str()內容並無不同
repr([1,2,3,4])## '[1, 2, 3, 4]'x = [1]
x.append(2)
x## [1, 2]x.append([3, 4])
x## [1, 2, [3, 4]]"The list x is " + repr(x)## 'The list x is [1, 2, [3, 4]]'repr(len)## '<built-in function len>'repr(list)## "<class 'list'>"from datetime import datetime
now = datetime.now()
str(now)## '2021-04-07 14:40:55.179231'print(now)## 2021-04-07 14:40:55.179231repr(now)
## 'datetime.datetime(2021, 4, 7, 14, 40, 55, 179231)'%格式化字串舊式做法
常用的格式化規範
| 字串 | 意義 |
|---|---|
| %s | 字串 |
| %c | 字元 |
| %b | 二進位 |
| %d | 十進位 |
| %x | 十六進位 |
| %f | 浮點數 |
| %e | 指數 |
| 不指名 | 與d相同 |
errno = 12345
name = "Bob"
"Hello, %s" % name # %s 告訴Python此處要替換成字串，他會到第二個 % 運算子後面找到變數## 'Hello, Bob'"%x" % errno # %x 把整數轉換成字串並以16進位數字表示## '3039'"Hi, %s, 錯誤:0x%x 發生了" % (name, errno)## 'Hi, Bob, 錯誤:0x3039 發生了'"Hi, %(Name)s, 錯誤:0x%(errNo)x 發生了" % {"errNo":errno, "Name":name} ## 'Hi, Bob, 錯誤:0x3039 發生了'format()格式化字串"{} is the {} of {}".format("Ambrosia", "food", "the gods")
## 'Ambrosia is the food of the gods'"{{Ambrosia}} is the {} of {}".format("food", "the gods")
# 若格式化字串內需顯示{與}字元，則需重複寫兩次{{與}}## '{Ambrosia} is the food of the gods'"{} + {} = {}".format(1, 2, 1+2)## '1 + 2 = 3'x = [1, 2, "three"]
"The {} contains: {}".format("list", x)## "The list contains: [1, 2, 'three']""{2} is the {0} of {1}".format("food", "the gods", "Ambrosia")## 'Ambrosia is the food of the gods''{0}{1}{0}'.format('abc', 'def')## 'abcdefabc'"{food} is the food of {user}".format(food="Ambrosia", user="the gods")
## 'Ambrosia is the food of the gods'"{0} is the food of {user[1]}".format("Ambrosia", user=["men", "the gods", "others"])
# "{0} is the food of {user}".format(user="the gods", "Ambrosia")
# SyntaxError: non-keyword arg after keyword arg## 'Ambrosia is the food of the gods'import math
"{}為 {}".format("圓周率", math.pi)
## '圓周率為 3.141592653589793'"{:10s}為 {:10.5f}".format("圓周率", math.pi)
# 寬度為10, 類型為字串,字串預設靠左
# 寬度為10, 取5位小數點, 類型為浮點數(f), 數字預設靠右
## '圓周率 為 3.14159'"{:>10s}為 {:+10.5f}".format("圓周率", math.pi)
# 寬度為10, 類型為字串,字串靠右
# 寬度為10, 取5位小數點, 類型為浮點數(f), 數字預設靠右, 並顯示+-號
## ' 圓周率為 +3.14159'"{0:*<10s}為 {1:#> 10.5f}".format("圓周率", math.pi)
# 寬度為10, 靠左(<), 多餘空格用*字元填滿, 並以編號0來取得format()內第0個參數
# 寬度為10, 取5位小數點, 類型為浮點數(f), 空格代表若為正數就留空格，若為負數則加負號, 剩下空格用#字元填滿, 並用編號1來取得format()內第1個參數## '圓周率*******為 ## 3.14159'"{0:*<10s}為 {1:#>+10.5f}".format("圓周率", math.pi)
## '圓周率*******為 ##+3.14159'"{name:P^10s}為 {value:=+10.2f}".format(name = "圓周率", value = math.pi)
# 寬度為10, 置中(^), 多餘空格用P字元填滿, 並以名稱name來取得format()內參數
# 寬度為10, 取2位小數點, 類型為浮點數(f), +號代表強制加上+-號, =號代表把正負號放到最左邊## 'PPP圓周率PPPP為 + 3.14'可直接將Python運算式嵌入字串中
速度較快
name = "Bob"
f'你好, {name}!'## '你好, Bob!'a = 5
b = 10
name = "Peter"
No = 100
f'5 加 10 等於 {a + b}, 而非 {2 * (a + b)}.'## '5 加 10 等於 15, 而非 30.'f'Hi~ {name:s}, 有錯誤 0x{errno:x} 發生了！'
# :s代表字串
# :x代表十六進位數## 'Hi~ Peter, 有錯誤 0x3039 發生了！'f'Hello, {name:s}'## 'Hello, Peter'f'Hello, {name=}' # 變數名稱後面加『=』, 就會把變數名稱與內容一起印出來## "Hello, name='Peter'"f'Hello, {No=}' # 變數名稱後面加『=』, 就會把變數名稱與內容一起印出來## 'Hello, No=100'