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Is there a way to append r' to a sting in Python dynamically?

I am new to Python and I am working to calculate checksum of a string that has backslashes (). I was able to come up with a logic to calculate the checksum but that function needs the string to be in raw format (r') to calculate the correct checksum. However this function will be invoked by another function and I will not be able to convert the string to raw string manually. Can someone please help me on how to achieve this dynamically.
Here is the string:
raw_message1 = '=K+8\\\08|'
This string has 3 backslashes however it shows only 2 after saving and this string may vary again so replacing after processing will not help.
And when I print the result:
print(message1)
=K+8\ 8|
What I need is to have something that retains the backslashes as is. I cannot go for any other character as every character has its own ASCII value and checksum would differ. I tried all the other options mentioned before and see different result for each case.

You can define the string as so:
message1 = r'=K+8\\08|'
This should make the string message1 be in raw form.
Let me know if this helps. I don't really understand what you mean by converting to raw string manually and converting it dynamically. This is the most I can help with for now.

All the r prefix does is manually add backslashes so you don't have to, it doesn't "magically" retain the backslashes, instead it replaces them with double backslashes so they are interpreted as single backslashes.
Look at the following example:
>>> s = r"\rando\\\mst\ri\ngo\\flet\ters"
>>> s
'\\rando\\\\\\mst\\ri\\ngo\\\\flet\\ters'
>>> print(s)
\rando\\\mst\ri\ngo\\flet\ters
>>>
The string actually contains double backslashes and when printed they are interpreted as single backslashes.

What is the right way to encode a string with backslashes? [duplicate]

This question already has answers here:
How to fix "<string> DeprecationWarning: invalid escape sequence" in Python?
(2 answers)
Closed 4 years ago.
In the given example: "\info\more info\nName"
how would I turn this into bytes
I tried using unicode-escape but that didn't seem to work :(
data = "\info\more info\nName"
dataV2 = str.encode(data)
FinalData = dataV2.decode('unicode-escape').encode('utf_8')
print(FinalData)
This is were I should get b'\info\more info\nName'
but something unexpected happens and I get DeprecationWarnings in my terminal
I'm assuming that its because of the backslashes causing a invalid sequence but I need them for this project

Backslashes before characters indicate an attempt to escape the character that follows to make it into a special character of some sort. You get the DeprecationWarning because Python is (finally) going to make unrecognized escapes an error, rather than silently treating them as a literal backslash followed by the character.
To fix, either double your backslashes (not sure if you intended a newline; if so, double double the backslash before the n):
data = "\\info\\more info\\nName"
or, if you want all the backslashes to be literal backslashes (the \n shouldn't be a newline), then you can use a raw string by prefixing with r:
data = r"\info\more info\nName"
which disables backslashes interpolation for everything except the quote character itself.
Note that if you just let data echo in the interactive interpreter, it will show the backslashes as doubled (because it implicitly uses the repr of the str, which is what you'd type to reproduce it). To avoid that, print the str to see what it would actually look like:
>>> "\\info\\more info\\nName" # repr produced by simply evaluating it, which shows backslashes doubled, but there's really only one each time
"\\info\\more info\\nName"
>>> print("\\info\\more info\\nName") # print shows the "real" contents
\info\more info\nName
>>> print("\\info\\more info\nName") # With new line left in place
\info\more info
Name
>>> print(r"\info\more info\nName") # Same as first option, but raw string means no doubling backslashes
\info\more info\nName

You can escape a backslash with another backslash.
data = "\\info\\more info\nName"
You could also use a raw string for the parts that don't need escapes.
data = r"\info\more info""\nName"
Note that raw strings don't work if the final character is a backslash.

pushing a list to a file in python

I have a list like this
dis=('a','b','c',100)
I want it to push to a .Csv file(plan_to_prod2) ,but my folder name is a integer
my_df = pd.DataFrame(dis)
my_df.to_csv('E:\23\4\plan_to_prod2.csv')
i am getting invalid file name as error even though my file name is correct

You should use a raw string literal.
A \ followed by an integer is interpreted as a unicode character which is an invalid file name. Try print('E:\23\4\plan_to_prod2.csv') and see the output (I would have pasted it here but these characters don't show up when the answer is rendered). You can also see the problem in the error you provided in the comment.
When using raw string:
print(r'E:\23\4\plan_to_prod2.csv')
# E:\23\4\plan_to_prod2.csv
Instead of using raw string you can also use double slashes, ie print('E:\\23\\4\\plan_to_prod2.csv') but I find using raw strings much easier.

The \ character is used for escapes. So when you try to find the path you escape.
You should use / or use raw string r'' instead of \. Also, you could escape those backslashes by escaping it with an additional \.Choose whichever suits you best.
r'E:\23\4\plan_to_prod2.csv'
'E:\\23\\4\\plan_to_prod2.csv'
'E:/23/4/plan_to_prod2.csv'

Error "(unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape" [duplicate]

This question already has answers here:
How should I write a Windows path in a Python string literal?
(5 answers)
Closed 3 years ago.
I'm trying to read a CSV file into Python (Spyder), but I keep getting an error. My code:
import csv
data = open("C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener")
data = csv.reader(data)
print(data)
I get the following error:
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes
in position 2-3: truncated \UXXXXXXXX escape
I have tried to replace the \ with \\ or with / and I've tried to put an r before "C.., but all these things didn't work.

This error occurs, because you are using a normal string as a path. You can use one of the three following solutions to fix your problem:
1: Just put r before your normal string. It converts a normal string to a raw string:
pandas.read_csv(r"C:\Users\DeePak\Desktop\myac.csv")
2:
pandas.read_csv("C:/Users/DeePak/Desktop/myac.csv")
3:
pandas.read_csv("C:\\Users\\DeePak\\Desktop\\myac.csv")

The first backslash in your string is being interpreted as a special character. In fact, because it's followed by a "U", it's being interpreted as the start of a Unicode code point.
To fix this, you need to escape the backslashes in the string. The direct way to do this is by doubling the backslashes:
data = open("C:\\Users\\miche\\Documents\\school\\jaar2\\MIK\\2.6\\vektis_agb_zorgverlener")
If you don't want to escape backslashes in a string, and you don't have any need for escape codes or quotation marks in the string, you can instead use a "raw" string, using "r" just before it, like so:
data = open(r"C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener")

You can just put r in front of the string with your actual path, which denotes a raw string. For example:
data = open(r"C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener")

Consider it as a raw string. Just as a simple answer, add r before your Windows path.
import csv
data = open(r"C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener")
data = csv.reader(data)
print(data)

Try writing the file path as "C:\\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener" i.e with double backslash after the drive as opposed to "C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener"

Add r before your string. It converts a normal string to a raw string.

As per String literals:
String literals can be enclosed within single quotes (i.e. '...') or double quotes (i.e. "..."). They can also be enclosed in matching groups of three single or double quotes (these are generally referred to as triple-quoted strings).
The backslash character (i.e. \) is used to escape characters which otherwise will have a special meaning, such as newline, backslash itself, or the quote character. String literals may optionally be prefixed with a letter r or R. Such strings are called raw strings and use different rules for backslash escape sequences.
In triple-quoted strings, unescaped newlines and quotes are allowed, except that the three unescaped quotes in a row terminate the string.
Unless an r or R prefix is present, escape sequences in strings are interpreted according to rules similar to those used by Standard C.
So ideally you need to replace the line:
data = open("C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener")
To any one of the following characters:
Using raw prefix and single quotes (i.e. '...'):
data = open(r'C:\Users\miche\Documents\school\jaar2\MIK\2.6\vektis_agb_zorgverlener')
Using double quotes (i.e. "...") and escaping backslash character (i.e. \):
data = open("C:\\Users\\miche\\Documents\\school\\jaar2\\MIK\\2.6\\vektis_agb_zorgverlener")
Using double quotes (i.e. "...") and forwardslash character (i.e. /):
data = open("C:/Users/miche/Documents/school/jaar2/MIK/2.6/vektis_agb_zorgverlener")

Just putting an r in front works well.
eg:
white = pd.read_csv(r"C:\Users\hydro\a.csv")

It worked for me by neutralizing the '' by f = open('F:\\file.csv')

The double \ should work for Windows, but you still need to take care of the folders you mention in your path. All of them (except the filename) must exist. Otherwise you will get an error.

Explicitly make a string into raw string

I am reading reading path to the registry from a text file. The registry path is
HKEY_LOCAL_MACHINE\Software\MYAPP\6.3
I store this registry in a variable :
REGISTRY_KEY
Then I strip the HKEY_LOCAL_MACHINE part from the string and try to read the value at the key.
if REGISTRY_KEY.split('\\')[0] == "HKEY_LOCAL_MACHINE":
keyPath = REGISTRY_KEY.strip("HKEY_LOCAL_MACHINE\\")
try:
key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE, keyPath)
value = winreg.QueryValueEx(key, "InstallPath")[0]
except IOError as err:
print(err)
I get the following error
[WinError 2] The system cannot find the file specified
However if I do it manually like
key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE,r'Software\MYAPP\6.3')
OR
key = winreg.OpenKey(winreg.HKEY_LOCAL_MACHINE,"Software\\MYAPP\\6.3")
it works.
So is there any way I can make the keyPath variable to either be a raw string or contain double '\'
PS:I am using Python 3.3

A raw str is a way of entering the string so you do not need to escape special characters. Another way to enter the same str is to escape the special characters (blackslash being one of them). They would have the same data. So really your question doesn't have an answer.
You are also using strip incorrectly, but it would not matter for this particular string. Because the first character after the first \ is S and S is not in your strip command and your key ends in a digit also not in your strip command. But you will want to fix it so other keys are not messed up by this. You got lucky on this string.
>>> r"HKEY_LOCAL_MACHINE\Software\MYAPP\6.3".strip("HKEY_LOCAL_MACHINE\\")
'Software\\MYAPP\\6.3'
As for your real problem. There is something else about the string that is wrong. Try print repr(keyPath) before your call to OpenKey
EDIT: looks like SylvainDefresne guessed correctly about a newline character on the end of the string

Your REGISTRY_KEY.strip() call is not doing what you think it's doing. It doesn't remove the string HKEY_LOCAL_MACHINE\ from the beginning of the string. Instead, it removes the characters H, K, E, etc., in any order, from both ends of the string. This is why it works when you manually put in what you expect.
As for your original question, a double backslash is an escape sequence that produces a single backslash in your string, so it is not necessary to convert keyPath to double slashes.