I am writing a python MapReduce word count program. Problem is that there are many non-alphabet chars strewn about in the data, I have found this post Stripping everything but alphanumeric chars from a string in Python which shows a nice solution using regex, but I am not sure how to implement it
def mapfn(k, v):
print v
import re, string ….
I have read multiple posts regarding this error, but I still can’t figure it out. When I try to loop through my function:
def fix_Plan(location):
letters_only = re.sub(“[^a-zA-Z]”, # Search for all non-letters
” “, # Replace all non-letters with spaces
location) # Column and row….
I want to take the string 0.71331, 52.25378 and return 0.71331,52.25378 – i.e. just look for a digit, a comma, a space and a digit, and strip out the space.
This is my current code:
coords = ‘0.71331, 52.25378’
coord_re = re.sub(“(\d), (\d)”, “\1,\2”, coords)
print coord_re
But this gives me 0.7133,2.25378. What am I doing wrong?
….
While trying to learn a little more about regular expressions, a tutorial suggested that you can use the \b to match a word boundary. However, the following snippet in the Python interpreter does not work as expected:
>>> x = ‘one two three’
>>> y = re.search(“\btwo\b”, x)
It should have been a match object if anything was matched, but it is None….
I want to get the first match of a regex.
In this case, I have a list:
text = ‘aa33bbb44’
re.findall(‘\d+’,text)
[’33’, ’44’]
I could extract the first element of the list:
text = ‘aa33bbb44’
re.findall(‘\d+’,text)[0]
’33’
But that only works if there is at least one match, otherwise I’ll get an error:
text = ‘aazzzbbb’
re.findall(‘\d+’,text….
What is the pythonic way to split a string before the occurrences of a given set of characters?
For example, I want to split
‘TheLongAndWindingRoad’
at any occurrence of an uppercase letter (possibly except the first), and obtain
[‘The’, ‘Long’, ‘And’, ‘Winding’, ‘Road’].
Edit: It should also split single occurrences, i.e.
from ‘ABC’ I’d like to….
I’m trying to find every 10 digit series of numbers within a larger series of numbers using re in Python 2.6.
I’m easily able to grab no overlapping matches, but I want every match in the number series. Eg.
in “123456789123456789”
I should get the following list:
[1234567891,2345678912,3456789123,4567891234,5678912345,6789123456,7891234567,891234….
I want to filter strings in a list based on a regular expression.
Is there something better than [x for x in list if r.match(x)] ?
….
I’m having a bit of trouble getting a Python regex to work when matching against text that spans multiple lines. The example text is (‘\n’ is a newline)
some Varying TEXT\n
\n
DSJFKDAFJKDAFJDSAKFJADSFLKDLAFKDSAF\n
[more of the above, ending with a newline]\n
[yep, there is a variable number of lines here]\n
\n
(repeat the above a few hundred times….
Cleaning the values of a multitype data frame in python/pandas, I want to trim the strings. I am currently doing it in two instructions :
import pandas as pd
df = pd.DataFrame([[‘ a ‘, 10], [‘ c ‘, 5]])
df.replace(‘^\s+’, ”, regex=True, inplace=True) #front
df.replace(‘\s+$’, ”, regex=True, inplace=True) #end
df.values
This is quite slow….