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Cleaning text using regex library not working properly

I have a text that I need to clean for further processing.
Here is the sample text:
Nigel Reuben Rook Williams (15 July 1944 – 21 April 1992) was an
English conservator and expert on the restoration of ceramics and
glass. From 1961 until his death he worked at the British Museum,
where he became the Chief Conservator of Ceramics and Glass in 1983.
There his work included the successful restorations of the Sutton Hoo
helmet and the Portland Vase.
Joining as an assistant at age 16, Williams spent his entire career,
and most of his life, at the British Museum. He was one of the first
people to study conservation, not yet recognised as a profession, and
from an early age was given responsibility over high-profile objects.
In the 1960s he assisted with the re-excavation of the Sutton Hoo
ship-burial, and in his early- to mid-twenties he conserved many of
the objects found therein: most notably the Sutton Hoo helmet, which
occupied a year of his time. He likewise reconstructed other objects
from the find, including the shield, drinking horns, and maplewood
bottles.
The "abiding passion of his life" was ceramics,[4] and the 1970s and
1980s gave Williams ample opportunities in that field. After nearly
31,000 fragments of shattered Greek vases were found in 1974 amidst
the wreck of HMS Colossus, Williams set to work piecing them together.
The process was televised, and turned him into a television
personality. A decade later, in 1988 and 1989, Williams's crowning
achievement came when he took to pieces the Portland Vase, one of the
most famous glass objects in the world, and put it back together. The
reconstruction was again televised for a BBC programme, and as with
the Sutton Hoo helmet, took nearly a year to complete.
I need to:
split the text into sentences (by the full stop symbol '.'), eliminating the full stop symbol
split the sentences into words (only latin alphabet letters), other symbols should be replaced by the space character and only single spaces should be used to separate those words
Show all text in lowercase
I'm using a Mac and I get this code running:
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import re
fread = open('source.txt')
fwrite = open('result.txt','w+')
for line in fread:
new_line = line
# split the text into sentences
new_line = re.sub(r"\." , "\r", new_line)
# change all uppercase letters to lowercase
new_line = new_line.lower()
# only latin letters
new_line = re.sub("[^a-z\s]", " ", new_line)
# The words should be separated by single spaces.
new_line = re.sub(r" +"," ", new_line)
# Getting rid of space in the beginning of the sentence
new_line = re.sub(r"ˆ\s+", "", new_line)
fwrite.write(new_line)
fread.close()
fwrite.close()
The result was not quite as expected. The spaces in the beginning of each line were not deleted. I ran the same code in a Windows machine and I noticed that sometines the full stop was replaced by the and some other times by . So I'm not sure what is happening.
Here is a sample of the result. Since spaces where not shown in stackoverflow, I had to show text as code:
nigel reuben rook williams july april was an english conservator and expert on the restoration of ceramics and glass
from until his death he worked at the british museum where he became the chief conservator of ceramics and glass in
there his work included the successful restorations of the sutton hoo helmet and the portland vase
joining as an assistant at age williams spent his entire career and most of his life at the british museum
he was one of the first people to study conservation not yet recognised as a profession and from an early age was given responsibility over high profile objects
in the s he assisted with the re excavation of the sutton hoo ship burial and in his early to mid twenties he conserved many of the objects found therein most notably the sutton hoo helmet which occupied a year of his time
he likewise reconstructed other objects from the find including the shield drinking horns and maplewood bottles
the abiding passion of his life was ceramics and the s and s gave williams ample opportunities in that field
after nearly fragments of shattered greek vases were found in amidst the wreck of hms colossus williams set to work piecing them together
the process was televised and turned him into a television personality
a decade later in and williams s crowning achievement came when he took to pieces the portland vase one of the most famous glass objects in the world and put it back together
the reconstruction was again televised for a bbc programme and as with the sutton hoo helmet took nearly a year to complete
Different characters may not appear as I see, for instance, before joining I see two ?? using TextWrangler.
Using the lstrip() function works to delete the spaces in the beginning of each sentence, by the way.
Why don't <new_line = re.sub(r"ˆ\s+", "", new_line)> work?
I suspect that the '\n' used to mark the end of the line is generating some problems.

# split the sentences into words
new_line = re.sub("[^a-z\s]", " ", new_line)
This isn't doing what the comment says. It's actually replacing all non-letter, non-space characters with a space, which is why your output is missing numbers and punctuation.
# Getting rid of space in the beginning of the sentence
new_line = re.sub(r"ˆ\s+", "", new_line)
I don't know what character is at the front of that regex, but it's not the beginning-of-line character ^.

A few mentions here:
Use context manager for in/out files because it handles closing after usage by default.
You have a wrong character as John Gordon say.
I recommend using some regex visualization tool (i.e. https://jex.im/regulex/)
Basic approach to replace something with only whitespace is to use plus operator [^a-z]+: (non-alphabet chars)+(one and more).
So the final code snippet I've made
# !/usr/bin/env python
# -*- coding: utf-8 -*-
import re
# It's better to use context manager to read files.
# You don't have to explicitly close those files after reading.
with open('./source.txt', 'r') as source:
text = ''
for line in source:
text += line.lower() # Lower case on reading, why not.
# only latin letters & single spaces at the same time
text = re.sub("[^a-z.]+", " ", text)
# # replace dots with newlines
text = re.sub(r'\.', r'\n', text)
with open('./result.txt', 'w+') as output:
output.write(text)

Regex parse Buffy Script using look behinds

I'm having a difficult time parsing this page: http://www.buffyworld.com/buffy/transcripts/114_tran.html
I'm attempting to get the character name with the associated dialogue.
The text looks like this:
<p>BUFFY: Wait!
<p>She stands there panting, watching the truck turn a corner.
<p>BUFFY: (whining) Don't you want your garbage?
<p>She sighs, pouts, turns and walks back toward the house.
<p>Cut to the kitchen. Buffy enters through the back door, holding a pile of
mail. She begins looking through it. We see Dawn standing by the island.
<p>DAWN: Hey Buffy. Oh, don't forget, today's trash day.<br>BUFFY: (sourly)
Thanks.
<p>Dawn piles her books into her school bag. Buffy opens a letter.
<p>Close shot of the letter.
<p>
<p>Dawn smiles, and she and Willow exit. Buffy picks up the still-wrapped
sandwich and stares at it.
<p>BUFFY: (to herself) Somebody should.
<p>She sighs, puts the sandwich back in the bag.
<p>Cut to the Bronze. Pan across various people drinking and dancing,
bartender serving. Reveal Xander and Anya sitting at the bar eating chips from
several bags. A notebook sits in front of them bearing the wedding seating
chart.
<p>ANYA: See ... this seating chart makes no sense. We have to do it again.
(Xander nodding) We can't do it again. You do it.<br>XANDER: The seating
chart's fine. Let's get back to the table arrangements. I'm starting to have
dreams of gardenia bouquets. (winces) I am so glad my manly coworkers didn't
just hear me say that. (eating chips)
Ideally, I'd match from <p> or <br> to the next <p> or <br>. I was trying to use look aheads and look behinds for this:
reg = "((?<=<p>)|(?<=<br>))(?P<character>.+):(?P<dialogue>.+)((?=<p>)|(?=<br>))"
script = re.findall(reg, html_text)
Unfortunately, this doesn't match anything. When I leave off the lookahead ((?=<p>)|(?=<br>)), I match lines as long as there isn't a newline in the matching dialogue. It seems to terminate at the newline instead of continuing to the <p>
ex. On this line, the "Thanks" isn't matched. <p>DAWN: Hey Buffy. Oh, don't forget, today's trash day.<br>BUFFY: (sourly)
Thanks.
Thank you for any insight you have!

Work around the dot notation:
re.findall('((?<=<p>)|(?<=<br>))([A-Z]+):([^<]+)', text)
Also you can try a special flag to include linebreaks into the semantics of the dot. Personally, when I can I use splits or some html parser. RE escaping, all the parameters, limitations and flags can drive mad anyone. There is also re.split.
dialogs = {}
text = html_text.replace('<br>', '<p>')
paragraphs = text.split('<p>')
for p in paragraphs:
if ":" in p:
char, line = p.split(":", 1)
if char in dialogs:
dialogs[char].append(line)
else:
dialogs[char] = []

How to capture from whitespace +{n} to next {n} in regex

I've cleaned up a document to allow me to properly rip it verse by verse. Being weak in regex I cannot seem to find the right expression to extract these verses.
This is the expression I am using:
(\t?\t?{\d+}.*){
And I'm doing this in python, though I expect that does not matter.
How should I change this to make it simply highlight verses {x} some verse {x} next verse, but stopping short just of the next brace?
As you can see, I'm trying to keep it tabs-aware because this doc gives some attention to verse-style writing.
And here is an example doc:
{1} The words of the blessing of Enoch, wherewith he blessed the elect [[[[and]]]] righteous, who will be living in the day of tribulation, when all the wicked [[[[and godless]]]] are to be removed. {2} And he took up his parable and said--Enoch a righteous man, whose eyes were opened by God, saw the vision of the Holy One in the heavens, [[which]] the angels showed me, and from them I heard everything, and from them I understood as I saw, but not for this generation, but for a remote one which is for to come. {3} Concerning the elect I said, and took up my parable concerning them:
The Holy Great One will come forth from His dwelling,
{4} And the eternal God will tread upon the earth, (even) on Mount Sinai,
[[And appear from His camp]]
And appear in the strength of His might from the heaven of heavens.
{5} And all shall be smitten with fear
And the Watchers shall quake,
And great fear and trembling shall seize them unto the ends of the earth.
{6} And the high mountains shall be shaken,
And the high hills shall be made low,
And shall melt like wax before the flame
{7} And the earth shall be [[wholly]] rent in sunder,
And all that is upon the earth shall perish,
And there shall be a judgement upon all (men).
{8} But with the righteous He will make peace.
And will protect the elect,
And mercy shall be upon them.
And they shall all belong to God,
And they shall be prospered,
And they shall [[all]] be blessed.
[[And He will help them all]],
And light shall appear unto them,
[[And He will make peace with them]].
{9} And behold! He cometh with ten thousands of [[His]] holy ones
To execute judgement upon all,
And to destroy [[all]] the ungodly:
And to convict all flesh
Of all the works [[of their ungodliness]] which they have ungodly committed,
And of all the hard things which ungodly sinners [[have spoken]] against Him.
[BREAK]
[CHAPTER 2]

Simply split the text on the verse markers with re.split:
import re
text = '''{1} The words of the blessing of Enoch, wherewith he blessed the elect [[[[and]]]] righteous, who will be living in the day of tribulation, when all the wicked [[[[and godless]]]] are to be removed. {2} And he took up his parable and said--Enoch a righteous man, whose eyes were opened by God, saw the vision of the Holy One in the heavens, [[which]] the angels showed me, and from them I heard everything, and from them I understood as I saw, but not for this generation, but for a remote one which is for to come. {3} Concerning the elect I said, and took up my parable concerning them:
The Holy Great One will come forth from His dwelling,
{4} And the eternal God will tread upon the earth, (even) on Mount Sinai,
[[And appear from His camp]]
And appear in the strength of His might from the heaven of heavens.'''
result = [i for i in re.split(r'\{\d+\}', text) if i]
result has four elements, corresponding to {1} through {4} above.

(\t?\t?{\d+}.*?)(?={)
See demo.
https://regex101.com/r/OCpDb7/1
Edit:
If you want to capture last verse as well,use
(\t?\t?{\d+}.*?)(?={|\[BREAK\])
See demo.
https://regex101.com/r/OCpDb7/2
Your original regex suffered from 2 problems.
(\t?\t?{\d+}.*){
^ ^
1)You had used greedy operator.Use non greedy .*?
2)You were capturing { which would not allow that verse to match as it has been already captured.Use lookahead to just assert and not capture.

The answer above is good, but the verses are not always incremented properly in this book (ie, it can jump from verse 5 to 7 due to manuscript details) so I had to retain the verses to "pluck the number" them later. Basically, entire verses along with the number had to be extracted.
The recipe seemed to be this:
verse = re.compile(r'([\t+]?{\d+}[^{]*)', re.DOTALL)
In context:
import re
f = open('thebook.txt', 'r').read()
chapters = f.split('[BREAK]')
verse = re.compile(r'([\t+]?{\d+}[^{]*)', re.DOTALL)
verses = re.findall(verse, chapters[1])
Please note, it seems to work properly, but I have to check the results to make sure it accounts for everything.

Removing "\n"s when printing sentences from text file in python?

I am trying to print a list of sentences from a text file (one of the Project Gutenberg eBooks). When I print the file as a single string string it looks fine:
file = open('11.txt','r+')
alice = file.read()
print(alice[:500])
Output is:
ALICE'S ADVENTURES IN WONDERLAND
Lewis Carroll
THE MILLENNIUM FULCRUM EDITION 3.0
CHAPTER I. Down the Rabbit-Hole
Alice was beginning to get very tired of sitting by her sister on the
bank, and of having nothing to do: once or twice she had peeped into the
book her sister was reading, but it had no pictures or conversations in
it, 'and what is the use of a book,' thought Alice 'without pictures or
conversations?'
So she was considering in her own mind (as well as she could, for the
hot d
Now, when I split it into sentences (The assignment was specifically to do this by "splitting at the periods," so it's a very simplified split), I get this:
>>> print(sentences[:5])
["ALICE'S ADVENTURES IN WONDERLAND\n\nLewis Carroll\n\nTHE MILLENNIUM FULCRUM EDITION 3", '0\n\n\n\n\nCHAPTER I', " Down the Rabbit-Hole\n\nAlice was beginning to get very tired of sitting by her sister on the\nbank, and of having nothing to do: once or twice she had peeped into the\nbook her sister was reading, but it had no pictures or conversations in\nit, 'and what is the use of a book,' thought Alice 'without pictures or\nconversations?'\n\nSo she was considering in her own mind (as well as she could, for the\nhot day made her feel very sleepy and stupid), whether the pleasure\nof making a daisy-chain would be worth the trouble of getting up and\npicking the daisies, when suddenly a White Rabbit with pink eyes ran\nclose by her", "\n\nThere was nothing so VERY remarkable in that; nor did Alice think it so\nVERY much out of the way to hear the Rabbit say to itself, 'Oh dear!\nOh dear! I shall be late!' (when she thought it over afterwards, it\noccurred to her that she ought to have wondered at this, but at the time\nit all seemed quite natural); but when the Rabbit actually TOOK A WATCH\nOUT OF ITS WAISTCOAT-POCKET, and looked at it, and then hurried on,\nAlice started to her feet, for it flashed across her mind that she had\nnever before seen a rabbit with either a waistcoat-pocket, or a watch\nto take out of it, and burning with curiosity, she ran across the field\nafter it, and fortunately was just in time to see it pop down a large\nrabbit-hole under the hedge", '\n\nIn another moment down went Alice after it, never once considering how\nin the world she was to get out again']
Where do the extra "\n" characters come from and how can I remove them?

If you want to replace all the newlines with one space, do this:
import re
new_sentences = [re.sub(r'\n+', ' ', s) for s in sentences]

You may not want to use regex, but I would do:
import re
new_sentences = []
for s in sentences:
new_sentences.append(re.sub(r'\n{2,}', '\n', s))
This should replace all instances of two or more '\n' with a single newline, so you still have newlines, but don't have "extra" newlines.
If you want to avoid creating a new list, and instead modify the existing one (credit to #gavriel and Andrew L.: I hadn't thought of using enumerate when I first posted my answer):
import re
for i, s in enumerate(sentences):
sentences[i] = re.sub(r'\n{2,}', '\n', s)
The extra newlines aren't really extra, by which I mean they are meant to be there and are visible in the text in your question: the more '\n' there are, the more space there is visible between the lines of text (i.e., one between the chapter heading and the first paragraph, and many between the edition and the chapter heading.

You'll understand where the \n characters come from with this little example:
alice = """ALICE'S ADVENTURES IN WONDERLAND
Lewis Carroll
THE MILLENNIUM FULCRUM EDITION 3.0
CHAPTER I. Down the Rabbit-Hole
Alice was beginning to get very tired of sitting by her sister on the
bank, and of having nothing to do: once or twice she had peeped into the
book her sister was reading, but it had no pictures or conversations in
it, 'and what is the use of a book,' thought Alice 'without pictures or
conversations?'
So she was considering in her own mind (as well as she could, for the
hot d"""
print len(alice.split("."))
print len(alice.split("\n"))
It all depends the way you're splitting your text, the above example will give this output:
3
19
Which means there are 3 substrings if you were to split the text using . or 19 substrings if you splitted using \n as separator. You can read more about str.split
In your case you've splitted your text using ., so the 3 substrings will contain multiple newlines characters \n, to get rid of them you can either split these substrings again or just get rid of them using str.replace

The text uses newlines to delimit sentences as well as fullstops. You have an issue where just replacing the new line characters with an empty string will result in having words without spaces between them. Before you split alice by '.', I would use something along the lines of #elethan's solution to replace all of the multiple new lines in alice with a '.' Then you could do alice.split('.') and all of the sentences separated with multiple new lines would be split appropriately along with the sentences separated with . initially.
Then your only issue is the decimal point in the version number.

file = open('11.txt','r+')
file.read().split('\n')

How to prevent closing of " in variable

I have a variable
sentence = "In 1794, shortly after his arrival in Manchester, Dalton was elected a member of the Manchester Literary and Philosophical Society, the "Lit & Phil", and a few weeks later he communicated his first paper on "Extraordinary facts relating to the vision of colours", in which he postulated that shortage in colour perception was caused by discoloration of the liquid medium of the eyeball. In fact, a shortage of colour perception in some people had not even been formally described or officially noticed until Dalton wrote about his own. Since both he and his brother were colour blind, he recognized that this condition must be hereditary."
Now this may have both "" and '' due to which it will close the value of the variable. I want to prevent this. Is there any other way of storing a string?

Escape the embedded quotes with \:
"Some text with \"embedded\" quotes"
If your text contains only double quotes, you can single quotes and not have to escape the double quotes:
'Some text with "embedded" quotes'
Last but not least, you can triple the outer quotes and save yourself having to escape newlines too:
"""Some text with "embedded" quotes"""
"""Some text with "embedded" quotes
and a newline too"""
For your example, single quotes would already do the trick:
sentence = 'In 1794, shortly after his arrival in Manchester, Dalton was elected a member of the Manchester Literary and Philosophical Society, the "Lit & Phil", and a few weeks later he communicated his first paper on "Extraordinary facts relating to the vision of colours", in which he postulated that shortage in colour perception was caused by discoloration of the liquid medium of the eyeball. In fact, a shortage of colour perception in some people had not even been formally described or officially noticed until Dalton wrote about his own. Since both he and his brother were colour blind, he recognized that this condition must be hereditary.'

a="""triple quoted strings can contain quote like this " without ending the string"""

You can use triple quotes like:
sentence = """ long sentence with all 'kind" of symbols """