CODEWITHSUNDEEP
pythonstringstring-formattingpython-3.5
user5813071
user5813071

Reputation:

Tuples inside of python string formatting?

Basically, I'm trying to templatize Latex code where I need to output strings like B_{i}, and I'd like to call string formatting to change i. But the problem is that using Python's string formatting - which uses tuples to denote arguments - has been causing me trouble when I want to maintain tuples in my outputted string.

EXAMPLE

Suppose I have:

subscript = "22"
value = "10"
stringy = "B_{{0}} = {1}".format(subscript, value)"

When I print stringy I get:

B_{0} = 10

I'd like to get:

B_{22} = 10

Upvotes: 1

Views: 127

Answers (4)

grovina
grovina

Reputation: 3077

You need one more pair of curly brackets:

subscript = "22"
value = "10"
stringy = "B_{{{0}}} = {1}".format(subscript, value)

print(stringy)  # 'B_{22} = 10'

This is because you need double ("{{") to print a literal curly bracket. The two on the outside print the literal {} and the middle {0} gets replaced by subscript.

Upvotes: 1

kindall
kindall

Reputation: 184455

You're almost there. You correctly doubled up the { and } characters so that they appear literally in the formatted result. However, you now don't have any placeholder for the first value, which needs to be represented as {0} in your format string.

So:

stringy = "B_{{{0}}} = {1}".format(subscript, value)

Upvotes: 2

Moses Koledoye
Moses Koledoye

Reputation: 78554

Double the outer braces to escape those, therefore making a total of 3 pairs:

stringy = "B_{{{0}}} = {1}".format(subscript, value)
print(stringy)
# B_{22} = 10

As seen in your current solution, the doubled braces {{...}} are escaped and do not take part in the formatting. You therefore need to include that extra layer of braces.

Upvotes: 2

Patrick Haugh
Patrick Haugh

Reputation: 61063

print("B_{{{0}}} = {1}".format(subscript, value))

The {{ will print out a { character in the output, so you need another {} to actually access the variable

Upvotes: 2

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