[python] How can I selectively escape percent (%) in Python strings?

I have the following code

test = "have it break."
selectiveEscape = "Print percent % in sentence and not %s" % test

print(selectiveEscape)

I would like to get the output:

Print percent % in sentence and not have it break.

What actually happens:

    selectiveEscape = "Use percent % in sentence and not %s" % test
TypeError: %d format: a number is required, not str

Alternatively, as of Python 2.6, you can use new string formatting (described in PEP 3101):

'Print percent % in sentence and not {0}'.format(test)

which is especially handy as your strings get more complicated.

If the formatting template was read from a file, and you cannot ensure the content doubles the percent sign, then you probably have to detect the percent character and decide programmatically whether it is the start of a placeholder or not. Then the parser should also recognize sequences like %d (and other letters that can be used), but also %(xxx)s etc.

Similar problem can be observed with the new formats -- the text can contain curly braces.

If you are using Python 3.6 or newer, you can use f-string:

>>> test = "have it break."
>>> selectiveEscape = f"Print percent % in sentence and not {test}"
>>> print(selectiveEscape)
... Print percent % in sentence and not have it break.

try using %% to print % sign .

I have tried different methods to print a subplot title, look how they work. It's different when i use Latex.

It works with '%%' and 'string'+'%' in a typical case.

If you use Latex it worked using 'string'+'\%'

So in a typical case:

import matplotlib.pyplot as plt
fig,ax = plt.subplots(4,1)
float_number = 4.17
ax[0].set_title('Total: (%1.2f' %float_number + '\%)')
ax[1].set_title('Total: (%1.2f%%)' %float_number)
ax[2].set_title('Total: (%1.2f' %float_number + '%%)')
ax[3].set_title('Total: (%1.2f' %float_number + '%)')

Title examples with %

If we use latex:

import matplotlib.pyplot as plt
import matplotlib
font = {'family' : 'normal',
        'weight' : 'bold',
        'size'   : 12}
matplotlib.rc('font', **font)
matplotlib.rcParams['text.usetex'] = True
matplotlib.rcParams['text.latex.unicode'] = True
fig,ax = plt.subplots(4,1)
float_number = 4.17
#ax[0].set_title('Total: (%1.2f\%)' %float_number) This makes python crash
ax[1].set_title('Total: (%1.2f%%)' %float_number)
ax[2].set_title('Total: (%1.2f' %float_number + '%%)')
ax[3].set_title('Total: (%1.2f' %float_number + '\%)')

We get this: Title example with % and latex

You can't selectively escape %, as % always has a special meaning depending on the following character.

In the documentation of Python, at the bottem of the second table in that section, it states:

'%'        No argument is converted, results in a '%' character in the result.

Therefore you should use:

selectiveEscape = "Print percent %% in sentence and not %s" % (test, )

(please note the expicit change to tuple as argument to %)

Without knowing about the above, I would have done:

selectiveEscape = "Print percent %s in sentence and not %s" % ('%', test)

with the knowledge you obviously already had.