python词典的items()用法

 

tl;nr:

for ... in ...	dict.items	dict
x, y	把元组/键值对当中的元素分别打印	不成立，会报错
x	把键值对作为一个整体x，结果为元组/键值对	把键值对x, a[x]中的元素分别打印

 

 

 

 

 

---

 

items() 主要用于提取词典中的key: value对

scores = {
             "Rick Sanchez": 70,
             "Morty Smith": 35,
             "Summer Smith": 82,
             "Jerry Smith": 23,
             "Beth Smith": 98
          }
 
passed = [n for n,s in scores.items() if s>=65]
print(passed)

 

 举例：

a = {
    "a": 1,
    "b": 2,
    "c": 3,

 

1、a.items() - 将词典变为键值对的数组

print(a.items())     

#output: dict_items([('b', 2), ('a', 1), ('c', 3)])

① 由于打印变量时不是标准数据类型，因此会加上命名以及( )，即最外层的括号

② items()把词典变成了元组的数列（aka键值对的数组）因此打印结果为 [(  )] 的格式

 

 

2、items()语法

 

1) for x in a.items()  --- 将把键值对作为一个整体x 元组/键值对，因此结果是键值对本身

for x in a.items():
    print(x)


#output：
('b', 2)
('a', 1)
('c', 3)

注：因此当x是一个int时，if x in a.items 一定是false ！！！

 

2) for x,y in a.items()   --- 由于a.items是元组，该语法进一步把元组/键值对当中的元素分别打印

for x,y in a.items():
    print(x, y)

#output
b 2
a 1
c 3

（结果等同以下for x in dict用法）

 

 

3、for x in dict语法

 ①  in dict 语法是判断key是否在数组，因此for x,y【或a[x]】in a均不成立，会报错

 for x,y in a:     
     print(x, y)

#output: ValueError: need more than 1 value to unpack

 

②  in dict 是直接判断key是否在数组，并把键值对x, a[x]中的元素分别打印

for x in a:    
    print(x,a[x])

#output:
b 2
a 1
c 3

 

相关例题

nominated = {1931: ['Norman Taurog', 'Wesley Ruggles', 'Clarence Brown', 'Lewis Milestone', 'Josef Von Sternberg'], 1932: ['Frank Borzage', 'King Vidor', 'Josef Von Sternberg'], 1933: ['Frank Lloyd', 'Frank Capra', 'George Cukor'], 1934: ['Frank Capra', 'Victor Schertzinger', 'W. S. Van Dyke'], 1935: ['John Ford', 'Michael Curtiz', 'Henry Hathaway', 'Frank Lloyd'], 1936: ['Frank Capra', 'William Wyler', 'Robert Z. Leonard', 'Gregory La Cava', 'W. S. Van Dyke'], 1937: ['Leo McCarey', 'Sidney Franklin', 'William Dieterle', 'Gregory La Cava', 'William Wellman'], 1938: ['Frank Capra', 'Michael Curtiz', 'Norman Taurog', 'King Vidor', 'Michael Curtiz'], 1939: ['Sam Wood', 'Frank Capra', 'John Ford', 'William Wyler', 'Victor Fleming'], 1940: ['John Ford', 'Sam Wood', 'William Wyler', 'George Cukor', 'Alfred Hitchcock'], 1941: ['John Ford', 'Orson Welles', 'Alexander Hall', 'William Wyler', 'Howard Hawks'], 1942: ['Sam Wood', 'Mervyn LeRoy', 'John Farrow', 'Michael Curtiz', 'William Wyler'], 1943: ['Michael Curtiz', 'Ernst Lubitsch', 'Clarence Brown', 'George Stevens', 'Henry King'], 1944: ['Leo McCarey', 'Billy Wilder', 'Otto Preminger', 'Alfred Hitchcock', 'Henry King'], 1945: ['Billy Wilder', 'Leo McCarey', 'Clarence Brown', 'Jean Renoir', 'Alfred Hitchcock'], 1946: ['David Lean', 'Frank Capra', 'Robert Siodmak', 'Clarence Brown', 'William Wyler'], 1947: ['Elia Kazan', 'Henry Koster', 'Edward Dmytryk', 'George Cukor', 'David Lean'], 1948: ['John Huston', 'Laurence Olivier', 'Jean Negulesco', 'Fred Zinnemann', 'Anatole Litvak'], 1949: ['Joseph L. Mankiewicz', 'Robert Rossen', 'William A. Wellman', 'Carol Reed', 'William Wyler'], 1950: ['Joseph L. Mankiewicz', 'John Huston', 'George Cukor', 'Billy Wilder', 'Carol Reed'], 1951: ['George Stevens', 'John Huston', 'Vincente Minnelli', 'William Wyler', 'Elia Kazan'], 1952: ['John Ford', 'Joseph L. Mankiewicz', 'Cecil B. DeMille', 'Fred Zinnemann', 'John Huston'], 1953: ['Fred Zinnemann', 'Charles Walters', 'William Wyler', 'George Stevens', 'Billy Wilder'], 1954: ['Elia Kazan', 'George Seaton', 'William Wellman', 'Alfred Hitchcock', 'Billy Wilder'], 1955: ['Delbert Mann', 'John Sturges', 'Elia Kazan', 'Joshua Logan', 'David Lean'], 1956: ['George Stevens', 'Michael Anderson', 'William Wyler', 'Walter Lang', 'King Vidor'], 1957: ['David Lean', 'Mark Robson', 'Joshua Logan', 'Sidney Lumet', 'Billy Wilder'], 1958: ['Richard Brooks', 'Stanley Kramer', 'Robert Wise', 'Mark Robson', 'Vincente Minnelli'], 1959: ['George Stevens', 'Fred Zinnemann', 'Jack Clayton', 'Billy Wilder', 'William Wyler'], 1960: ['Billy Wilder', 'Jules Dassin', 'Alfred Hitchcock', 'Jack Cardiff', 'Fred Zinnemann'], 1961: ['J. Lee Thompson', 'Robert Rossen', 'Stanley Kramer', 'Federico Fellini', 'Robert Wise', 'Jerome Robbins'], 1962: ['David Lean', 'Frank Perry', 'Pietro Germi', 'Arthur Penn', 'Robert Mulligan'], 1963: ['Elia Kazan', 'Otto Preminger', 'Federico Fellini', 'Martin Ritt', 'Tony Richardson'], 1964: ['George Cukor', 'Peter Glenville', 'Stanley Kubrick', 'Robert Stevenson', 'Michael Cacoyannis'], 1965: ['William Wyler', 'John Schlesinger', 'David Lean', 'Hiroshi Teshigahara', 'Robert Wise'], 1966: ['Fred Zinnemann', 'Michelangelo Antonioni', 'Claude Lelouch', 'Richard Brooks', 'Mike Nichols'], 1967: ['Arthur Penn', 'Stanley Kramer', 'Richard Brooks', 'Norman Jewison', 'Mike Nichols'], 1968: ['Carol Reed', 'Gillo Pontecorvo', 'Anthony Harvey', 'Franco Zeffirelli', 'Stanley Kubrick'], 1969: ['John Schlesinger', 'Arthur Penn', 'George Roy Hill', 'Sydney Pollack', 'Costa-Gavras'], 1970: ['Franklin J. Schaffner', 'Federico Fellini', 'Arthur Hiller', 'Robert Altman', 'Ken Russell'], 1971: ['Stanley Kubrick', 'Norman Jewison', 'Peter Bogdanovich', 'John Schlesinger', 'William Friedkin'], 1972: ['Bob Fosse', 'John Boorman', 'Jan Troell', 'Francis Ford Coppola', 'Joseph L. Mankiewicz'], 1973: ['George Roy Hill', 'George Lucas', 'Ingmar Bergman', 'William Friedkin', 'Bernardo Bertolucci'], 1974: ['Francis Ford Coppola', 'Roman Polanski', 'Francois Truffaut', 'Bob Fosse', 'John Cassavetes'], 1975: ['Federico Fellini', 'Stanley Kubrick', 'Sidney Lumet', 'Robert Altman', 'Milos Forman'], 1976: ['Alan J. Pakula', 'Ingmar Bergman', 'Sidney Lumet', 'Lina Wertmuller', 'John G. Avildsen'], 1977: ['Steven Spielberg', 'Fred Zinnemann', 'George Lucas', 'Herbert Ross', 'Woody Allen'], 1978: ['Hal Ashby', 'Warren Beatty', 'Buck Henry', 'Woody Allen', 'Alan Parker', 'Michael Cimino'], 1979: ['Bob Fosse', 'Francis Coppola', 'Peter Yates', 'Edouard Molinaro', 'Robert Benton'], 1980: ['David Lynch', 'Martin Scorsese', 'Richard Rush', 'Roman Polanski', 'Robert Redford'], 1981: ['Louis Malle', 'Hugh Hudson', 'Mark Rydell', 'Steven Spielberg', 'Warren Beatty'], 1982: ['Wolfgang Petersen', 'Steven Spielberg', 'Sydney Pollack', 'Sidney Lumet', 'Richard Attenborough'], 1983: ['Peter Yates', 'Ingmar Bergman', 'Mike Nichols', 'Bruce Beresford', 'James L. Brooks'], 1984: ['Woody Allen', 'Roland Joffe', 'David Lean', 'Robert Benton', 'Milos Forman'], 1985: ['Hector Babenco', 'John Huston', 'Akira Kurosawa', 'Peter Weir', 'Sydney Pollack'], 1986: ['David Lynch', 'Woody Allen', 'Roland Joffe', 'James Ivory', 'Oliver Stone'], 1987: ['Bernardo Bertolucci', 'Adrian Lyne', 'John Boorman', 'Norman Jewison', 'Lasse Hallstrom'], 1988: ['Barry Levinson', 'Charles Crichton', 'Martin Scorsese', 'Alan Parker', 'Mike Nichols'], 1989: ['Woody Allen', 'Peter Weir', 'Kenneth Branagh', 'Jim Sheridan', 'Oliver Stone'], 1990: ['Francis Ford Coppola', 'Martin Scorsese', 'Stephen Frears', 'Barbet Schroeder', 'Kevin Costner'], 1991: ['John Singleton', 'Barry Levinson', 'Oliver Stone', 'Ridley Scott', 'Jonathan Demme'], 1992: ['Clint Eastwood', 'Neil Jordan', 'James Ivory', 'Robert Altman', 'Martin Brest'], 1993: ['Jim Sheridan', 'Jane Campion', 'James Ivory', 'Robert Altman', 'Steven Spielberg'], 1994: ['Woody Allen', 'Quentin Tarantino', 'Robert Redford', 'Krzysztof Kieslowski', 'Robert Zemeckis'], 1995: ['Chris Noonan', 'Tim Robbins', 'Mike Figgis', 'Michael Radford', 'Mel Gibson'], 1996: ['Anthony Minghella', 'Joel Coen', 'Milos Forman', 'Mike Leigh', 'Scott Hicks'], 1997: ['Peter Cattaneo', 'Gus Van Sant', 'Curtis Hanson', 'Atom Egoyan', 'James Cameron'], 1998: ['Roberto Benigni', 'John Madden', 'Terrence Malick', 'Peter Weir', 'Steven Spielberg'], 1999: ['Spike Jonze', 'Lasse Hallstrom', 'Michael Mann', 'M. Night Shyamalan', 'Sam Mendes'], 2000: ['Stephen Daldry', 'Ang Lee', 'Steven Soderbergh', 'Ridley Scott', 'Steven Soderbergh'], 2001: ['Ridley Scott', 'Robert Altman', 'Peter Jackson', 'David Lynch', 'Ron Howard'], 2002: ['Rob Marshall', 'Martin Scorsese', 'Stephen Daldry', 'Pedro Almodovar', 'Roman Polanski'], 2003: ['Fernando Meirelles', 'Sofia Coppola', 'Peter Weir', 'Clint Eastwood', 'Peter Jackson'], 2004: ['Martin Scorsese', 'Taylor Hackford', 'Alexander Payne', 'Mike Leigh', 'Clint Eastwood'], 2005: ['Ang Lee', 'Bennett Miller', 'Paul Haggis', 'George Clooney', 'Steven Spielberg'], 2006: ['Alejandro Gonzaalez Inarritu', 'Clint Eastwood', 'Stephen Frears', 'Paul Greengrass', 'Martin Scorsese'], 2007: ['Julian Schnabel', 'Jason Reitman', 'Tony Gilroy', 'Paul Thomas Anderson', 'Joel Coen', 'Ethan Coen'], 2008: ['David Fincher', 'Ron Howard', 'Gus Van Sant', 'Stephen Daldry', 'Danny Boyle'], 2009: ['James Cameron', 'Quentin Tarantino', 'Lee Daniels', 'Jason Reitman', 'Kathryn Bigelow'], 2010: ['Darren Aronofsky', 'David O. Russell', 'David Fincher', 'Ethan Coen', 'Joel Coen', 'Tom Hooper']}
winners = {1931: ['Norman Taurog'], 1932: ['Frank Borzage'], 1933: ['Frank Lloyd'], 1934: ['Frank Capra'], 1935: ['John Ford'], 1936: ['Frank Capra'], 1937: ['Leo McCarey'], 1938: ['Frank Capra'], 1939: ['Victor Fleming'], 1940: ['John Ford'], 1941: ['John Ford'], 1942: ['William Wyler'], 1943: ['Michael Curtiz'], 1944: ['Leo McCarey'], 1945: ['Billy Wilder'], 1946: ['William Wyler'], 1947: ['Elia Kazan'], 1948: ['John Huston'], 1949: ['Joseph L. Mankiewicz'], 1950: ['Joseph L. Mankiewicz'], 1951: ['George Stevens'], 1952: ['John Ford'], 1953: ['Fred Zinnemann'], 1954: ['Elia Kazan'], 1955: ['Delbert Mann'], 1956: ['George Stevens'], 1957: ['David Lean'], 1958: ['Vincente Minnelli'], 1959: ['William Wyler'], 1960: ['Billy Wilder'], 1961: ['Jerome Robbins', 'Robert Wise'], 1962: ['David Lean'], 1963: ['Tony Richardson'], 1964: ['George Cukor'], 1965: ['Robert Wise'], 1966: ['Fred Zinnemann'], 1967: ['Mike Nichols'], 1968: ['Carol Reed'], 1969: ['John Schlesinger'], 1970: ['Franklin J. Schaffner'], 1971: ['William Friedkin'], 1972: ['Bob Fosse'], 1973: ['George Roy Hill'], 1974: ['Francis Ford Coppola'], 1975: ['Milos Forman'], 1976: ['John G. Avildsen'], 1977: ['Woody Allen'], 1978: ['Michael Cimino'], 1979: ['Robert Benton'], 1980: ['Robert Redford'], 1981: ['Warren Beatty'], 1982: ['Richard Attenborough'], 1983: ['James L. Brooks'], 1984: ['Milos Forman'], 1985: ['Sydney Pollack'], 1986: ['Oliver Stone'], 1987: ['Bernardo Bertolucci'], 1988: ['Barry Levinson'], 1989: ['Oliver Stone'], 1990: ['Kevin Costner'], 1991: ['Jonathan Demme'], 1992: ['Clint Eastwood'], 1993: ['Steven Spielberg'], 1994: ['Robert Zemeckis'], 1995: ['Mel Gibson'], 1996: ['Anthony Minghella'], 1997: ['James Cameron'], 1998: ['Steven Spielberg'], 1999: ['Sam Mendes'], 2000: ['Steven Soderbergh'], 2001: ['Ron Howard'], 2002: ['Roman Polanski'], 2003: ['Peter Jackson'], 2004: ['Clint Eastwood'], 2005: ['Ang Lee'], 2006: ['Martin Scorsese'], 2007: ['Ethan Coen', 'Joel Coen'], 2008: ['Danny Boyle'], 2009: ['Kathryn Bigelow'], 2010: ['Tom Hooper']}


nom_count_dict = {}
# Add your solution code below before line 10. Add more lines for your code as needed.
for yn, n in nominated.items():
    for nomin_name in n:
        if nomin_name not in nom_count_dict:
            nom_count_dict[nomin_name] = 1
        else:
            nom_count_dict[nomin_name] += 1


print("nom_count_dict = {}
".format(nom_count_dict))