How to Efficiently Interpolate Variables into Strings in Python?

How to Interpolate Variables into Strings in Python

When constructing strings dynamically, it's often necessary to include values stored in variables. Python offers several methods to achieve this interpolation:

1. F-strings (Python 3.6 ):

F-strings provide a concise and modern way to insert variables into strings:

num = 40
plot.savefig(f'hanning{num}.pdf')

2. str.format():

str.format() allows for flexible formatting and variable substitution:

plot.savefig('hanning{0}.pdf'.format(num))

3. String Concatenation:

Concatenating strings with variables (converted to strings):

plot.savefig('hanning' + str(num) + '.pdf')

4. Conversion Specifier:

Using the % operator to specify variable type and position:

plot.savefig('hanning%s.pdf' % num)

5. Local Variable Names Trick:

Inserting local variable names into the formatting string:

plot.savefig('hanning%(num)s.pdf' % locals())

6. string.Template:

Using string.Template for more advanced formatting needs:

plot.savefig(string.Template('hanning${num}.pdf').substitute(locals()))

Additional Tips:

• Consider using dedicated functions like Python's os.path to create file paths.
• Avoid using ordinary string formatting for URL construction (use specialized tools).
• Never use string interpolation for SQL queries due to security risks (use proper techniques).
• For printing, prepare formatted strings first or use separate print calls.

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