Python 使用字典键值从字符串中获取第一个和最后一个值

Question

我得到了一个很奇怪的数据。我有一个包含键和值的字典，我想使用这本字典来搜索这些关键字是否仅从文本的 and/or 结尾而不是句子的中间开始。我尝试在下面创建简单的数据框来显示问题案例和我到目前为止尝试过的 python 代码。我如何让它只搜索句子的开头或结尾？这个搜索整个文本子字符串。

代码：

d = {'apple corp':'Company','app':'Application'} #dictionary
l1 = [1, 2, 3,4]
l2 = [
    "The word Apple is commonly confused with Apple Corp which is a business",
    "Apple Corp is a business they make computers",
    "Apple Corp also writes App",
    "The Apple Corp also writes App"
]
df = pd.DataFrame({'id':l1,'text':l2})
df['text'] = df['text'].str.lower()
df

原始数据框：

id   text 
1    The word Apple is commonly confused with Apple Corp which is a business         
2    Apple Corp is a business they make computers                                    
3    Apple Corp also writes App                                                      
4    The Apple Corp also writes App

试用代码：

def matcher(k):
    x = (i for i in d if i in k)
    # i.startswith(k) getting error
    return ';'.join(map(d.get, x))
df['text_value'] = df['text'].map(matcher)
df

错误： TypeError: 'in <string>' requires string as left operand, not bool 当我使用这个 x = (i for i in d if i.startswith(k) in k)

如果我尝试这个，则为空值x = (i for i in d if i.startswith(k) == True in k)

TypeError: sequence item 0: expected str instance, NoneType found 当我使用这个 x = (i.startswith(k) for i in d if i in k)

以上代码的结果...创建新字段'text_value'：

id   text                                                                            text_value
1    The word Apple is commonly confused with Apple Corp which is a business         Company;Application
2    Apple Corp is a business they make computers                                    Company;Application
3    Apple Corp also writes App                                                      Company;Application
4    The Apple Corp also writes App                                                  Company;Application

正在尝试获得这样的最终输出：

id   text                                                                            text_value
1    The word Apple is commonly confused with Apple Corp which is a business         NaN
2    Apple Corp is a business they make computers                                    Company
3    Apple Corp also writes App                                                      Company;Application
4    The Apple Corp also writes App                                                  Application

Answer 1

您需要一个 matcher 函数，它可以接受 flag，然后调用它两次以获得 startswith 和 endswith 的结果。

def matcher(s, flag="start"):
    if flag=="start":
        for i in d:
            if s.startswith(i):
                return d[i]
    else:
        for i in d:
            if s.endswith(i):
                return d[i]
    return None

df['st'] = df['text'].apply(matcher)
df['ed'] = df['text'].apply(matcher, flag="end")
df['text_value'] = df[['st', 'ed']].apply(lambda x: ';'.join(x.dropna()),1)
df = df[['id','text', 'text_value']]

text_value 列如下所示：

0                       
1                Company
2    Company;Application
3            Application
Name: text_value, dtype: object

Answer 2

joined = "|".join(d.keys())

pat = '(?i)^(?:the\s*)?(' + joined + ')\b.*?|.*\b(' + joined + ')$'+'|.*'

get = lambda x: d.get(x.group(1),"") + (';' +d.get(x.group(2),"") if x.group(2) else '')

df.text.str.replace(pat,get)


0                       
1                Company
2    Company;Application
3    Company;Application
Name: text, dtype: object

Python 使用字典键值从字符串中获取第一个和最后一个值

Python get first and last value from string using dictionary key values

dictionary

startswith

python-3.x

pandas

ends-with