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I am using python to do some text comparison. The text format is like 44=100. Let's say, I have 2 text, 44=100 and 44=3001. I call the string on the left of = is tag, right is value. Now I need to compare the tag and value for them. The tag must be the same, 44 equals 44, but the values don't have to, as long as its format is the same. ie. 100 and 3001 are in the same format(normal digits). But 1.0E+7 in 44=1.0E+7 is different. tThe point is on value comparison. ie. I write a script comp.py, when I run comp.py 2000 30010, I will get output true; while I run comp.py 100000 1.0E+8, output is false. How can I do it? I am thinking about converting the value into an regular expression and comparing it with other.
pseudo code:
rex1 = '100000'.getRegrex(), rex2 = '1.0E+8'.getRegrex(), rex1.compare(rex2)
Is it a feasible way? any advice?
rex1 = '100000'.getRegrex(), rex2 = '1.0E+8'.getRegrex(), rex1.compare(rex2)
Your approach is wrong. It is not only difficult but also illogical to "deduce" a regexp from a given string. What you would do is:
Define your types. With each type you would have a corresponding regexp.
Compare your input text against all your defined types and check which type it is of.
Compare the two types.
Actually, your idea of rex1 = '100000'.getRegrex() could be done
rex1 = re.compile('10000')
But as Thustmaster pointed out, you may want to define the regular expression with more abstraction of the pattern of your data.
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I am trying to detect if a string contains any element in an array. I want to know if the string(msg) has any element from the array(prefixes) in it.
I want this because I want to make a discord bot with multiple prefixes, heres my garbage if statement.
if msg.startswith(prefixes[any]):
The existing answers show two ways of doing a linear search, and this is probably your best choice.
If you need something more scalable (ie, you have a lot of potential prefixes, they're very long, and/or you need to scan very frequently) then you could write a prefix tree. That's the canonical search structure for this problem, but it's obviously a lot more work and you still need to profile to see if it's really worthwhile for your data.
Try something like this:
prefixes = ('a','b','i')
if msg.startswith(prefixes):
The prefixes must be tuple because startswith function does not supports lists as a parameter.
There are algorithms for such a search, however, a functional implementation in Python may look like this:
prefixes = ['foo', 'bar']
string = 'foobar'
result = any(map(lambda x: string.startswith(x), prefixes))
If you search for x at any position in string, then change string.startswith(x) to x in string.
UPDATE
According to #MisterMiyagi in comments, the following is a more readable (possibly more efficient) statement:
result = any(string.startswith(prefix) for prefix in prefixes)
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I need to pass a variable '3-123' to a method in python, but if I do str(3-123) I get '-120'. Tried iterating, but I got an error cause it's an int.
You simply pass the string "3-123".
Your expression str(3-123) tells Python to first evaluate what is in parentheses, which is very clearly the arithmetic expression 3-123. That evaluation mandates a subtraction.
UPDATE PER USER COMMENT
Since you just got it returned from REST, then it's already a string. It seems that your problem is that you're building an expression string to be evaluated in SQL. In this case, you need to build the string you're going to send to SQL, at the character level. For this one item you would extend your 3-123 string with quotation marks:
from_rest = "3-123" # In practice, this comes directly from your REST return value.
to_sql = '"' + from_rest + '"'
This leaves you with a variable that contains the string "3-123" -- seven characters, rather than the original five.
Is that what you needed?
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While learning python, I could not find the difference between the use of str() and " ".
First code
Second code
With str() function you are changing the number type to String but with "" you just pass the String.
str(3.14) # 3.14 is a number and your are converting it into String.
"3.14" is an String value.
Imagine if you had a variable
pi=3.14
then
str(pi)
would give the result 3.14
whereas
"pi"
would give the result pi. The str() function converts something to its string form. Whereas simple quotes will return the word itself.
str() returns a string representation of an object, while quotation marks indicate the value is a string. To see the difference, consider the following:
x = 3.14
print("x") #outputs the character x
print(str(x)) #string representation of the value of object x
In the first print(), the actual character 'x' is output. This has nothing to with the variable x. However, in the second print(), the value of the object x is converted to a string, so '3.14' is output.
There is no difference between the two. The program will run the same. CodeCademy requires that you use the skills (functions and methods) that it teaches you in that step in order to progress to the next one. The python script doesn't do anything differently, but the CodeCademy code analyzer notices that you didn't accomplish the task the way they wanted you too.
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I have a content like this:
aid: "1168577519", cmt_id = 1168594403;
Now I want to get all number sequence：
1168577519
1168594403
by regex.
I have never meet regex problem, but this time I should use it to do some parse job.
Now I can just get sequence after "aid" and "cmt_id" respectively. I don't know how to merge them into one regex.
My current progress:
pattern = re.compile('(?<=aid: ").*?(?=",)')
print pattern.findall(s)
and
pattern = re.compile('(?<=cmt_id = ).*?(?=;)')
print pattern.findall(s)
There are many different approaches to designing a suitable regular expression which depend on the range of possible inputs you are likely to encounter.
The following would solve your exact question but could fail given different styled input. You need to provide more details, but this would be a start.
re_content = re.search("aid\: \"([0-9]*?)\",\W*cmt_id = ([0-9]*?);", input)
print re_content.groups()
This gives the following output:
('1168577519', '1168594403')
This example assumes that there might be other numbers in your input, and you are trying to extract just the aid and cmt_id values.
The simplest solution is to use re.findall
Example
>>> import re
>>> string = 'aid: "1168577519", cmt_id = 1168594403;'
>>> re.findall(r'\d+', string)
['1168577519', '1168594403']
>>>
\d+ matches one or more digits.
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for some reason when I get regex to get the number i need it returns none.
But when I run it here http://regexr.com/38n3o it works
the regex was designed to get the last number of the ip so it can be removed
lanip=74.125.224.72
notorm=re.search("/([1-9])\w+$/g", lanip)
That is not how you define a regular expressions in Python. The correct way would be:
import re
lanip="74.125.224.72"
notorm=re.search("([1-9])\w+$", lanip)
print notorm
Output:
<_sre.SRE_Match object at 0x10131df30>
You were using a javascript regex style. To read more on correct python syntax read the documentation
If you want to match the last number of an IP use:
import re
lanip="74.125.224.72"
notorm=re.search("(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)", lanip)
print notorm.group(4)
Output:
72
Regex used from http://www.regular-expressions.info/examples.html
Your example did work in this scenario, but would match a lot of false positives.
What is lanip's type? That can't run.
It needs to be a string, i.e.
lanip = "74.125.224.72"
Also your RE syntax looks strange, make sure you've read the documentation on Python's RE syntax.