Python正则表达式
1. 主要作用
在某个大文本里搜索需要的字段
2.所需文本
poem.txt
Very quietly I take my leave
As quietly as I came here;
Quietly I wave good-bye
To the rosy clouds in the western sky.
The golden willows by the riverside
Are young brides in the setting sun;
Their reflections on the shimmering waves
Always linger in the depth of my heart.
The floating heart growing in the sludge
Sways leisurely under the water;
In the gentle waves of Cambridge
I would be a water plant!
That pool under the shade of elm trees
Holds not water but the rainbow from the sky;
Shattered to pieces among the duckweeds
Is the sediment of a rainbow-like dream?
To seek a dream? Just to pole a boat upstream
To where the green grass is more verdant;
Or to have the boat fully loaded with starlight
And sing aloud in the splendour of starlight.
But I cannot sing aloud
Quietness is my farewell music;
Even summer insects help silence for me
Silent is Cambridge tonight!
Very quietly I take my leave
As quietly as I came here;
Gently I flick my sleeves
Not even a wisp of cloud will I bring away
3.代码实现
1.导入re库
import re
2.导入文件
text = ""
file = open("poem.txt")
for line in file:
text=text+line
file.close()
3.文本操作
-
在text中找所有的“to”
result = re.findall("to",text) print result 以后根据需求补充
4. 其他注意
- 正则表达式不仅能处理字符串数据也可以处理数值数据
