I am trying to find if a "\n" character is in a string using this:
if "\n" in errors.text
This works fine for a string like "one\ntwo" but when the newline is at the end of the string like "one\n", it doesn't seem to work. I am using selenium to get this string from a website. Is it possible that it is not catching the newline at the end and simply not including it?
Or could this be the problem?
fixedText = errors.text.split("\n")[0]
I want the fixed text to remove all newlines and only get the first line of text. It works except for the case discussed above
If you want the fixed text to only be the first line in a string, you can do this:
if errors.text: # skips empty strings
fixedText = errors.text.split("\n")[0]
This is because split() is reasonably robust:
>>> 'a'.split()[0]
'a'
>>> 'a\n'.split()[0]
'a'
>>> 'a\n1'.split()[0]
'a'
>>> ''.split()
[]
That last example demonstrates why we check for an empty string before trying to index the resulting list.
Related
I ultimately want to split a string by a certain character. I tried Regex, but it started escaping \, so I want to avoid that with another approach (all the attempts at unescaping the string failed). So, I want to get all positions of a character char in a string that is not within quotes, so I can split them up accordingly.
For example, given the phase hello-world:la\test, I want to get back 11 if char is :, as that is the only : in the string, and it is in the 11th index. However, re does split it, but I get ['hello-world,lat\\test'].
EDIT:
#BoarGules made me realize that re didn't actually change anything, but it's just how Python displays slashes.
Here's a function that works:
def split_by_char(string,char=':'):
PATTERN = re.compile(rf'''((?:[^\{char}"']|"[^"]*"|'[^']*')+)''')
return [string[m.span()[0]:m.span()[1]] for m in PATTERN.finditer(string)]
string = 'hello-world:la\test'
char = ':'
print(string.find(char))
Prints
11
char_index = string.find(char)
string[:char_index]
Returns
'hello-world'
string[char_index+1:]
Returns
'la\test'
Solution for the case you're likely encountering (a pseudo-CSV format you're hand-rolling a parser for; if you're not in that situation, it's still a likely situation for people finding this question later):
Just use the csv module.
import csv
import io
test_strings = ['field1:field2:field3', 'field1:"field2:with:embedded:colons":field3']
for s in test_strings:
for row in csv.reader(io.StringIO(s), delimiter=':'):
print(row)
Try it online!
which outputs:
['field1', 'field2', 'field3']
['field1', 'field2:with:embedded:colons', 'field3']
correctly ignoring the colons within the quoted field, requiring no kludgy, hard-to-verify hand-written regexes.
I'm trying to check if a subString exists in a string using regular expression.
RE : re_string_literal = '^"[a-zA-Z0-9_ ]+"$'
The thing is, I don't want to match any substring. I'm reading data from a file:
Now one of the lines have this text:
cout<<"Hello"<<endl;
I just want to check if there's a string inside the line and if yes, store it in a list.
I have tried the re.match method but it only works if we have to match a pattern, but in this case, I just want to check if a string exists or not, if yes, store it somewhere.
re_string_lit = '^"[a-zA-Z0-9_ ]+"$'
text = 'cout<<"Hello World!"<<endl;'
re.match(re_string_lit,text)
It doesn't output anything.
In simple words,
I just want to extract everything inside ""
If you just want to extract everything inside "" then string splitting would be much simpler way of doing things.
>>> a = 'something<<"actualString">>something,else'
>>> b = a.split('"')[1]
>>> b
'actualString'
The above example would only work for not more than 2 instances of double quotes ("), but you could make it work by iterating over every substring extracted using split method and applying a much simpler Regular Expression.
This worked for me:
re.search('"(.+?)"', 'cout<<"Hello"<<endl')
how should I delete everything on the string that starts with the letter I specify?
Let's say:
PHP/USD
I want to delete everything that starts with '/' so what's left would be 'PHP'
and how do I do the reverse? Starts so that USD would be the only one left?
I only found answers on deleting the middle or deleting string that starts with something, but no a PART of the string. What is the better approach on this?
is it something with oldstr.replace() replace documentation that I have misread?
Use re.sub and replace the pattern /.*$ with empty string:
import re
input = "PHP/USD"
line = re.sub(r"/.*$", "", input)
print line
# prints PHP
If you wanted the reverse, then use the pattern ^.*/.
I want to read regular expressions from a file, where each line contains a regex:
lorem.*
dolor\S*
The following code is supposed to read each and append it to a list of regex strings:
vocabulary=[]
with open(path, "r") as vocabularyFile:
for term in vocabularyFile:
term = term.rstrip()
vocabulary.append(term)
This code seems to escape the \ special character in the file as \\. How can I either avoid escaping or unescape the string so that it can be worked with as if I wrote this?
regex = r"dolor\S*"
You are getting confused by echoing the value. The Python interpreter echoes values by printing the repr() function result, and this makes sure to escape any meta characters:
>>> regex = r"dolor\S*"
>>> regex
'dolor\\S*'
regex is still an 8 character string, not 9, and the single character at index 5 is a single backslash:
>>> regex[4]
'r'
>>> regex[5]
'\\'
>>> regex[6]
'S'
Printing the string writes out all characters verbatim, so no escaping takes place:
>>> print(regex)
dolor\S*
The same process is applied to the contents of containers, like a list or a dict:
>>> container = [regex, 'foo\nbar']
>>> print(container)
['dolor\\S*', 'foo\nbar']
Note that I didn't echo there, I printed. str(list_object) produces the same output as repr(list_object) here.
If you were to print individual elements from the list, you get the same unescaped result again:
>>> print(container[0])
dolor\S*
>>> print(container[1])
foo
bar
Note how the \n in the second element was written out as a newline now. It is for that reason that containers use repr() for contents; to make otherwise hard-to-detect or non-printable data visible.
In other words, your strings do not contain escaped strings here.
I have the following read.json file
{:{"JOL":"EuXaqHIbfEDyvph%2BMHPdCOJWMDPD%2BGG2xf0u0mP9Vb4YMFr6v5TJzWlSqq6VL0hXy07VDkWHHcq3At0SKVUrRA7shgTvmKVbjhEazRqHpvs%3D-%1E2D%TL/xs23EWsc40fWD.tr","LAPTOP":"error"}
and python script :
import re
shakes = open("read.json", "r")
needed = open("needed.txt", "w")
for text in shakes:
if re.search('JOL":"(.+?).tr', text):
print >> needed, text,
I want it to find what's between two words (JOL":" and .tr) and then print it. But all it does is printing all the text set in "read.json".
You're calling re.search, but you're not doing anything with the returned match, except to check that there is one. Instead, you're just printing out the original text. So of course you get the whole line.
The solution is simple: just store the result of re.search in a variable, so you can use it. For example:
for text in shakes:
match = re.search('JOL":"(.+?).tr', text)
if match:
print >> needed, match.group(1)
In your example, the match is JOL":"EuXaqHIbfEDyvph%2BMHPdCOJWMDPD%2BGG2xf0u0mP9Vb4YMFr6v5TJzWlSqq6VL0hXy07VDkWHHcq3At0SKVUrRA7shgTvmKVbjhEazRqHpvs%3D-%1E2D%TL/xs23EWsc40fWD.tr, and the first (and only) group in it is EuXaqHIbfEDyvph%2BMHPdCOJWMDPD%2BGG2xf0u0mP9Vb4YMFr6v5TJzWlSqq6VL0hXy07VDkWHHcq3At0SKVUrRA7shgTvmKVbjhEazRqHpvs%3D-%1E2D%TL/xs23EWsc40fWD, which is (I think) what you're looking for.
However, a couple of side notes:
First, . is a special pattern in a regex, so you're actually matching anything up to any character followed by tr, not .tr. For that, escape the . with a \. (And, once you start putting backslashes into a regex, use a raw string literal.) So: r'JOL":"(.+?)\.tr'.
Second, this is making a lot of assumptions about the data that probably aren't warranted. What you really want here is not "everything between JOL":" and .tr", it's "the value associated with key 'JOL' in the JSON object". The only problem is that this isn't quite a JSON object, because of that prefixed :. Hopefully you know where you got the data from, and therefore what format it's actually in. For example, if you know it's actually a sequence of colon-prefixed JSON objects, the right way to parse it is:
d = json.loads(text[1:])
if 'JOL' in d:
print >> needed, d['JOL']
Finally, you don't actually have anything named needed in your code; you opened a file named 'needed.txt', but you called the file object love. If your real code has a similar bug, it's possible that you're overwriting some completely different file over and over, and then looking in needed.txt and seeing nothing changed each time…
If you know that your starting and ending matching strings only appear once, you can ignore that it's JSON. If that's OK, then you can split on the starting characters (JOL":"), take the 2nd element of the split array [1], then split again on the ending characters (.tr) and take the 1st element of the split array [0].
>>> text = '{:{"JOL":"EuXaqHIbfEDyvph%2BMHPdCOJWMDPD%2BGG2xf0u0mP9Vb4YMFr6v5TJzWlSqq6VL0hXy07VDkWHHcq3At0SKVUrRA7shgTvmKVbjhEazRqHpvs%3D-%1E2D%TL/xs23EWsc40fWD.tr","LAPTOP":"error"}'
>>> text.split('JOL":"')[1].split('.tr')[0]
'EuXaqHIbfEDyvph%2BMHPdCOJWMDPD%2BGG2xf0u0mP9Vb4YMFr6v5TJzWlSqq6VL0hXy07VDkWHHcq3At0SKVUrRA7shgTvmKVbjhEazRqHpvs%3D-%1E2D%TL/xs23EWsc40fWD'