Python 3 | Mehrere if-Anweisungen innerhalb einer for-Schleife verwenden?

Question

Ich habe gesucht und nichts gefunden, was meinen Bedürfnissen entspricht.

Ich habe drei for Schleifen, die jeweils eine if Bedingungen darin hat. Hier ist der Code:

for friend in friends: 
    columns = friend.split("\n") 
    if len(columns) == 4: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `no_of_new_posts`, `already_friends`) VALUES (?, ?, ?, ?)""", (columns)) 

for friend in friends: 
    columns = friend.split("\n") 
    if len(columns) == 3: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", (columns)) 

for friend in friends: 
    columns = friend.split("\n") 
    if len(columns) == 2: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", (columns)) 

Gibt es eine effizientere Möglichkeit, dies zu tun? Ich dachte an den and Operator wie folgt:

for friend in friends: 
    columns = friend.split("\n") 
    if len(columns) == 4: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `no_of_new_posts`, `already_friends`) VALUES (?, ?, ?, ?)""", (columns)) 
and 
     if len(columns) == 3: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", (columns)) 
and 
     if len(columns) == 2: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `already_friends`) VALUES (?, ?)""", (columns)) 

jeder kann das beste oder effizienteste Weg legen nahe, dies zu iterieren dreimal über die gleiche Liste wie apposed zu tun?

Answer 1

Voll Code hier:

for friend in friends: 
    columns = friend.split("\n") 
    if len(columns) == 4: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `no_of_new_posts`, `already_friends`) VALUES (?, ?, ?, ?)""", (columns)) 
    elif len(columns) == 3: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", (columns)) 
    elif len(columns) == 2: 
     c.execute("""INSERT INTO `fb_friends`(`name`, `already_friends`) VALUES (?, ?)""", (columns)) 

Answer 2

Sie suchen if/elif/else:

if len(smth) == 5: 
    # do this 
elif len(smth) == 6: 
    # do that 
else: 
    # do something else 

Answer 3

Oben ForceBru Antwort, die die sauberste ist ... hier ist eine Alternative zum Spaß.

d = {2: """INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", 
    3: """INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `already_friends`) VALUES (?, ?, ?)""", 
    4: """INSERT INTO `fb_friends`(`name`, `no_of_mutual_friends`, `no_of_new_posts`, `already_friends`) VALUES (?, ?, ?, ?)"""} 
for friend in friends: 
    columns = friend.split("\n") 
    try: 
     c.execute(d[len(columns)], (columns)) 
    except KeyError: 
     print("you sure about this columns length which was:", len(columns)) 

Answer 4

reqtemplate = "INSERT INTO `fb_friends`(%s) VALUES (%s)" 
fields = ['`name`', '`no_of_mutual_friends`', '`no_of_new_posts`', '`already_friends`'] 
for friend in friends: 
    columns = friend.split("\n") 
    lenc = len(columns) 
    c.execute(reqtemplate % (",".join(fields[:lenc]), ",".join("?" * lenc)), (columns))