How to 'raw text' a variable in Python?

Question

I am opening a workbook in openpyxl thus:

wb = load_workbook(r'seven.xlsx', data_only=True)

The name of the spreadsheet won't always be know in advance, so I need to rewrite this hardcoding to allow for a variable, while still maintaining the r?

If my variable name is sheet, then:

wb = load_workbook(sheet, data_only=True)

will omit the r.

And obviously I cannot do:

wb = load_workbook(r'sheet', data_only=True)

How do we achieve the prepending of r to a variable / how do we wrap a vriable within r''?

Stokowski

Your question doesn't make any sense. The r is just for string literals. – Frisian

The question makes perfect sense - there are times when you want to load configuration into a process from a text file, and in some instances, that text is liable to contain "tricky" characters. For example, say you want to parse a collection of regexes from json, or an old-style .ini file for some parameterised search. At some point, you've got to decode the sanitized string to turn it back into a "hot" one that can be parsed by the regex compiler. – Adrell

Possible related to this: https://mcmap.net/q/188774/-casting-raw-strings-python-duplicate – Caril

Answer 1

I did not understand really what you were trying to do, but if you have a string and you want to create a raw text there are two main methods I know of:
raw_text = [str_text]
and
str_text = "%r"%str_text
raw_text = str_text[1:-1].

Sigismund

This worked and just saved my night. But could you explain how it works? I've never seen a string operation like that. I'm on Python 3.7 so maybe it's from the older Python? – Geophagy

Answer 2

Your question makes no sense. The r prefix to indicates that backslash-something sequences in the string literal that follows is to be interpreted literally rather than as escape sequences. If you already have a string variable, then the contents of the variable are already correctly set.

Dulci

I invite you to then to try openpyxl.save() on a Windows machine for a file name (such as in the example above) that does not contain backslashes, and omitting r''. – Stokowski

What is the specific error that you have encountered? Please revise the question to provide complete background information about what you have tried and what failed. – Dulci

I don't think the example in question adds any context (it's openpyxl.loadworkbook(), but really it could be anything where a raw string is required but I want to pass a variable. Here it is anyway: #31363387 – Stokowski

Where in the docs does it say you have to use that? I have used openpyxl in the past (I prefer xlsxwriter now) and did not have to use raw string literals anywhere. Yes, on Windows. – Sadfaced

You must have misdiagnosed the problem. r'all_done.xlsx' is exactly the same as 'all_done.xlsx', since there are no backslashes inside the string literal. If it's unable to write the file, then the cause must be something else. If I had to speculate, maybe the "invalid mode" part is relevant — perhaps you don't have write permission to the current directory? – Dulci

@Sadfaced The docs don't say I have to use r''. Experience on Windows shows that I do. – Stokowski

Experience is no substitute for reasoning. The r prefix just makes it so that you can write r'C:\some\path\to\an.xlsx', which is less cumbersome than the equivalent 'C:\\some\\path\\to\\an.xlsx'. – Dulci