Python：比较列表和元组列表

Question

I have a list as shown below:

z = [('Anna Smith', 'IN1'), ('John', 'IN2'), ('Matt Andrew', 'IN3'), ('Smith', 'IN4')]

And another list:

c = ['Anna Smith', 'John', 'Anna', 'Smith']

I want the below output:

o = ['Anna Smith|IN1', 'John|IN2', 'Smith|IN4']

I have tried the below code:

for s, s_inc in z:
     for word in c:
          if word.lower() in s.lower():
                o.append("%s|%s"%(word, s_inc))

But the above gives me the output:

o = ['Anna Smith|IN1', 'Anna|IN1', 'Smith|IN1', 'John|IN2', 'Smith|IN4']

How do I get what I want?

Answer 1

List comprehension is an elegant method for this type of filtering/list manipulation problems.

The comprehension consists of three parts:

-First the the result is constructed in a+'|'+b

-Secondly, a and b are assigned to the first and second element in each 2-tuple in list z

-Thirdly we filter on the condition that a must be a member of list c

print [a+'|'+b for a,b in z if a in c]

# Prints ['Anna Smith|IN1', 'John|IN2', 'Smith|IN4']

Answer 2

From your examples, it seems you are looking for an exact match , so just use == instead of in :

for s, s_inc in z:
     for word in c:
          if word == s:
                o.append("%s|%s"%(word, s_inc))

Or shorter, as a single list comprehension:

o = ["%s|%s"%(s, s_inc) for s, s_inc in z if s in c]

After this, o is ['Anna Smith|IN1', 'John|IN2', 'Smith|IN4']

Answer 3

Try this:

z = [('Anna Smith', 'IN1'), ('John', 'IN2'), ('Matt Andrew', 'IN3'), ('Smith', 'IN4')]
c = set(['Anna Smith', 'John', 'Anna', 'Smith'])

o = [
    '|'.join([name, code]) for name, code in z if name in c   
]

Answer 4

I'd make c a set , for fast constant-time testing:

c_set = {w.lower() for w in c}

I lower-cased the words to make it easy to test for membership case-insensitively.

Then just use:

for s, s_inc in z:
    if s.lower() in c_set:
        o.append('|'.join([s, s_inc]))

or even:

o = ['|'.join([s, s_inc]) for s, s_inc in z if s.lower() in c_set]

to produce the whole list with a list comprehension.

Demo:

>>> z = [('Anna Smith', 'IN1'), ('John', 'IN2'), ('Matt Andrew', 'IN3'), ('Smith', 'IN4')]
>>> c = ['Anna Smith', 'John', 'Anna', 'Smith']
>>> c_set = {w.lower() for w in c}
>>> ['|'.join([s, s_inc]) for s, s_inc in z if s.lower() in c_set]
['Anna Smith|IN1', 'John|IN2', 'Smith|IN4']

Answer 5

>>> z = [('Anna Smith', 'IN1'), ('John', 'IN2'), ('Matt Andrew', 'IN3'), ('Smith', 'IN4')]
>>> c = ['Anna Smith', 'John', 'Anna', 'Smith']
>>> ['|'.join([i,x[1]]) for x in z for i in c if x[0]==i]
['Anna Smith|IN1', 'John|IN2', 'Smith|IN4']