Python中列表列表中的字符串操作

我有一个包含数百个子列表的列表。该列表来自数据库表，子列表是该表的行，因此子列表都具有相同数量的条目，并且条目的格式与相应子列表中的相同。以下是一个例子：

persons = [['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']] ...etc

如何编辑所有第5个字段以删除任何“-”和“/”符号

---

删除不需要的标志后，我如何创建一个包含所有人员信息的新列表，其中1）第5个字段最后一个数字是4，2）第6个字段颜色是“蓝色”？

要删除

-

和

/

，可以执行以下操作：

persons = [['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']]

for i in persons:
    i[4] = i[4].replace('-','').replace('/','')

print persons

[OUTPUT]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '210049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9306', 'Green']]

b = [x for x in persons if x[4][-2] == '4' and x[5]=='Blue']

对于第二个问题，您可以：

persons = [['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']]

for i in persons:
    i[4] = i[4].replace('-','').replace('/','')

print persons

[OUTPUT]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '210049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9306', 'Green']]

b = [x for x in persons if x[4][-2] == '4' and x[5]=='Blue']

简单：

for i in range(len(persons)):
    persons[i][4] = persons[i][4].replace('-', '').replace('/', '')

或

然后

及

---

答案是列表理解

persons = [p[:4]+[p[4].replace('-','').replace('/',''),p[5]] for p in persons]
p4 = [p for p in persons if p[4][-2]=='4']
pblue = [p for p in persons if p[5]=='Blue']

---

考虑以下几点：

persons = [
    ['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'],
    ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green'],
]

clean1 = [[aa, bb, cc, dd, ee.replace('/','').replace('-',''), ff] for [aa, bb, cc, dd, ee, ff] in persons]

def clean(ins):
    outs = ins
    outs = outs.replace('/', '')
    outs = outs.replace('-', '')
    return outs

clean2 = [[aa, bb, cc, dd, clean(ee), ff] for [aa, bb, cc, dd, ee, ff] in persons]

print clean1
print clean2

def modify1(s):
    e = list(s)
    e[-2] = '4'
    return ''.join(e)

modified1 = [[aa, bb, cc, dd, modify1(ee), 'Blue'] for [aa, bb, cc, dd, ee, ff] in clean1]

def modify2(s):
    return s[:-2] + '4' + s[-1]

modified2 = [[aa, bb, cc, dd, modify2(ee), 'Blue'] for [aa, bb, cc, dd, ee, ff] in clean1]

print modified1
print modified2

输出：

# persons
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']]

# clean
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 30 6', 'Green']]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 30 6', 'Green']]

# modified
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Blue'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 3046', 'Blue']]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Blue'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 3046', 'Blue']]

所有的方法都是简单的列表理解，根据您的具体要求考虑不同的选项。

# persons
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21-0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9/30-6', 'Green']]

# clean
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 30 6', 'Green']]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Green'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 30 6', 'Green']]

# modified
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Blue'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 3046', 'Blue']]
[['2014-2-20', 'Ivan', 'Jones', 'Moscow', '21 0049', 'Blue'], ['2014-1-12', 'Mike', 'Dyson', 'Glasgow', '9 3046', 'Blue']]