目标:
1)找到关键字旁边的单词(例如brca
)
2)创建包含此单词的新列
背景:
1)我有一个列表l
,我在其中生成一个数据帧df
,并使用以下代码从其中提取单词brca
:
l = ['carcinoma brca positive completion mastectomy',
'clinical brca gene mutation',
'carcinoma brca positive chemotherapy']
df = pd.DataFrame(l, columns=['Text'])
df['Gene'] = df['Text'].str.extract(r"(brca)")
输出:
Text Gene
0 breast invasive lobular carcinoma brca positiv... brca
1 clinical history brca gene mutation . gross de... brca
2 left breast invasive ductal carcinoma brca pos... brca
问题:
但是,我现在正在尝试为每一行查找单词brca
旁边的单词,并创建一个新列。
所需输出:
Text Gene NextWord
0 breast invasive lobular carcinoma brca positiv... brca positive
1 clinical history brca gene mutation . gross de... brca gene
2 left breast invasive ductal carcinoma brca pos... brca positive
我看过python pandas dataframe words in context: get 3 words before and after和PANDAS Finding the exact word and before word in a column of string and append that new column in python (pandas) column,但它们不太适合我。
问题:
我如何实现我的目标?
发布于 2019-05-28 02:24:26
我们可以使用python的内置方法partition
df['NextWord'] = df['Text'].apply(lambda x: x.partition('brca')[2]).str.split().str[0]
输出
Text Gene NextWord
0 carcinoma brca positive completion mastectomy brca positive
1 clinical brca gene mutation brca gene
2 carcinoma brca positive chemotherapy brca positive
说明
.partition
返回三个值:
之后的字符串
string = 'carcinoma brca positive completion mastectomy'
before, keyword, after = string.partition('brca')
print(before)
print(keyword)
print(after)
输出
carcinoma
brca
positive completion mastectomy
速度
我对答案之间的速度比较很好奇,因为我使用的是.apply
,但它是一个内置的方法。出乎意料的是,我的回答是最快的:
dfbig = pd.concat([df]*10000, ignore_index=True)
dfbig.shape
(30000, 2)
%%timeit
dfbig['Text'].apply(lambda x: x.partition('brca')[2]).str.split().str[0]
31.5 ms ± 1.36 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
%%timeit
dfbig['NextWord'] = dfbig['Text'].str.split('brca').str[1].str.split('\s').str[1]
74.5 ms ± 2.56 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
%%timeit
dfbig['NextWord'] = dfbig['Text'].str.extract(r"(?<=brca)(.+?) ")
40.7 ms ± 2.4 ms per loop (mean ± std. dev. of 7 runs, 10 loops each)
发布于 2019-05-28 02:24:38
大量使用pandas Series.str
访问器:
df['NextWord'] = df['Text'].str.split('brca').str[1].str.split('\s').str[1]
df
Text Gene NextWord
0 carcinoma brca positive completion mastectomy brca positive
1 clinical brca gene mutation brca gene
2 carcinoma brca positive chemotherapy brca positive
发布于 2019-05-28 02:29:50
使用:
import pandas as pd
l = ['carcinoma brca positive completion mastectomy',
'clinical brca gene mutation',
'carcinoma brca positive chemotherapy']
df = pd.DataFrame(l, columns=['Text'])
df['NextWord'] = df['Text'].str.extract(r"(?<=brca)(.+?) ")
print(df)
输出:
Text NextWord
0 carcinoma brca positive completion mastectomy positive
1 clinical brca gene mutation gene
2 carcinoma brca positive chemotherapy positive
https://stackoverflow.com/questions/56330620
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