CODEWITHSUNDEEP
pythonfilepython-2.7
jbaldwin
jbaldwin

Reputation: 924

Python inserting variable string as file name

I'm trying to create a file with a unique file name for every time my script runs. I am only intending to do this to every week or month. so I chose to use the date for the file name.

f = open('%s.csv', 'wb') %name

is where I'm getting this error.

Traceback (most recent call last):
File "C:\Users\User\workspace\new3\stjohnsinvoices\BabblevoiceInvoiceswpath.py", line 143,      in <module>
f = open('%s.csv', 'ab') %name
TypeError: unsupported operand type(s) for %: 'file' and 'str'

it works if I use a static filename, is there an issue with the open function, that means you can't pass a string like this?

name is a string and has values such as :

31/1/2013BVI

Many thanks for any help.

Upvotes: 27

Views: 202891

Answers (6)

elby
elby

Reputation: 1

import hashlib

filename = file_for_download
with open(filename, "rb") as f:
    bytes = f.read()  # read entire file as bytes
    msg_hash = hashlib.sha256(bytes).hexdigest();
    print(f"MSG_HASH = {msg_hash}")

Upvotes: -1

ran632
ran632

Reputation: 1199

Very similar to peixe.
You don't have to mention the number if the variables you add as parameters are in order of appearance

f = open('{}.csv'.format(name), 'wb')

Another option - the f-string formatting (ref):

f = open(f"{name}.csv", 'wb')

Upvotes: 7

Tom Lubenow
Tom Lubenow

Reputation: 1161

Even better are f-strings in python 3!

f = open(f'{name}.csv', 'wb')

Upvotes: 5

peixe
peixe

Reputation: 1292

And with the new string formatting method...

f = open('{0}.csv'.format(name), 'wb')

Upvotes: 5

Volatility
Volatility

Reputation: 32300

You need to put % name straight after the string:

f = open('%s.csv' % name, 'wb')

The reason your code doesn't work is because you are trying to % a file, which isn't string formatting, and is also invalid.

Upvotes: 50

avasal
avasal

Reputation: 14854

you can do something like

filename = "%s.csv" % name
f = open(filename , 'wb')

or f = open('%s.csv' % name, 'wb')

Upvotes: 7

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