How do I replace %s with a defined/non-empty variable string? Or rather what is the Pythonic or syntactic sugar for doing so?
Example:
# Replace %s with the value if defined by either vehicle.get('car') or vehicle.get('truck')
# Assumes only one of these values can be empty at any given time
# The get function operates like http://docs.python.org/2/library/xml.etree.elementtree.html#xml.etree.ElementTree.Element.get
logging.error("Found duplicate entry with %s", vehicle.get('car') or vehicle.get('truck'))
I think you want this:
'Found duplicate entry with %s' % (vehicle.get('car') or vehicle.get('truck'))
This will replace the '%s' with the non-empty string (assuming only one is non-empty). If both contain text, it will be replaced with the output of vehicle.get('car')
You could also use this type of string formatting:
'Found duplicate entry with {0}'.format(vehicle.get('car') or vehicle.get('truck'))
This will return the same result.
Have you tried something like this?
logging.error("Found duplicate entry with %s" % (vehicle.get('car') or vehicle.get('truck')))
Or if truck is also empty, you can return a default value:
logging.error("Found duplicate entry with %s" % (vehicle.get('car') or vehicle.get('truck', 'default')))
Related
Right now I have the method below, it works perfectly fine but I want to change part of the self.wait_for_element(....) to instead use %s rather than calling str(counter)
> def gather_recent_visited_courses_in_content_switcher(self):
hover_courses = self.browser.find_elements_by_xpath("//div[contains(#class, 'recent-content flyout-closed')]")
course_list = []
counter = 1
for course in hover_courses:
self.hover_over(course)
# Change the below to %s
self.wait_for_element("//div[contains(#class, 'fly-wrapper recent-content-trigger')][" + str(counter) + "]//div[contains(#class, 'recent-content-info')]", 'Course list not found')
course_display_name = course.find_element_by_xpath("//div[contains(#class, 'recent-content-info')]").text
course_list.append(str(course_display_name))
counter += 1
return course_list
Currently I keep getting errors when replacing it with [%s], like below
> self.wait_for_element("//div[contains(#class, 'fly-wrapper recent-content-trigger')][%s]//div[contains(#class, 'recent-content-info')]", 'Course list not found' %(counter))
Does anyone have any ideas on how to get this to work properly? So far, I keep getting 'not all arguments converted during string formatting' errors
The reason why using %s isn't working is because you are setting the placeholder value in the second string argument, and not the first string as you have intended.
With the first argument:
"//div[contains(#class, ...)][%s]//div[... 'recent-content-info')]"
Python can't find the proper value to replace %s with in the first string argument. So, that will raise an error.
As for the second argument:
'Course list not found' % (counter)
You are passing a value to the string but the string cannot be formatted to use the passed value because the string doesn't have placeholder, %s. So, that'll raise an error too.
To fix that, just format the first string argument. It'll look like this:
"//div[contains(#class, '...')][%s]//div[..., 'recent-content-info')]" % counter
Alternatively, you can use .format(). This the new style of string formatting. Using %s is considered to be the old style[1].
"//div[contains(#class, '...')][{}]//div[..., 'recent-co...')]".format(counter)
NOTE: Strings have been redacted to make things easier to read.
References
[1] - https://pyformat.info/
What is the difference between defining a variable and using it in a string and putting %s in a string and passing in the value after?
site = "Stackoverflow"
site + " is great!"
"%s is great!" % "Stackoverflow"
Printing either of these gives the same result so when is it better to use one over the other?
If you want to keep certain string constants in the same file, or on the top most of the file, you can declare the string with the placeholders as constants, then replace the placeholders with actual variable at run time through the % syntax.
This also allows greater re-usability.
Eg. you can store a single constant "%s is %s years old".
Using this syntax might also make the string more readable.
For two strings, there is little difference.
For multiple strings, s1 + s2 + s3 is less efficient, as it has to create a temporary str object for the first concatenation, where as both "%s %s %s" % (s1, s2, s3) and "{} {} {}".format(s1, s2, s3) creates the final str object immediately.
One:
'string' + 'string'
Two:
'%s %s' % ('one', 'two')
'{} {}'.format('one', 'two')
There is a great article on this here: https://pyformat.info/
Also the docs are a great resource: https://docs.python.org/2/library/string.html#format-string-syntax
Version one is less efficient with larger amounts of concatenation.
What does this python codes mean? New to python. THX!
benchmark_sets_list = [
'%s: %s' %
(set_name, benchmark_sets.BENCHMARK_SETS[set_name]['message'])
for set_name in benchmark_sets.BENCHMARK_SETS]
This part...
for set_name in benchmark_sets.BENCHMARK_SETS
...will grab the set names from benchmark_sets.BENCHMARK_SETS and it will keep them one by one into a set_name variable.
After that, it will be able to know the values from this line...
(set_name, benchmark_sets.BENCHMARK_SETS[set_name]['message'])
...because set_name will have a value. That part will return two things, set_name and benchmark_sets.BENCHMARK_SETS[set_name]['message']. Probably those two things will be both strings.
Then, those %s you see in this line...
'%s: %s' %
...will be replaced by the value of set_name and benchmark_sets.BENCHMARK_SETS[set_name]['message'] respectively. That will generate an string like this one: "foo: bar", being "foo" the value of set_name and "bar" the value of benchmark_sets.BENCHMARK_SETS[set_name]['message'].
In order for you to understand what happened there, this is a simple example:
"%s %s %s" % (first_elem, second_elem, third_elem)
That code will replace the first %s with the value of first_elem The second %s with the value of second_elem, and the third %s with the value of third_elem.
And finally that string will be added to the list which is being constructed. So, at the end you will have an list more or less like this one:
["foo: bar", "wop: wap", "bing: bang"]
When running the following code I would like to be able to store the returned values in a variable as a string. However when I run the code it will return the first name from the database in this format
[(u'Kiefer',)]
What would I need to change in order to just return a clean string? I was thinking I could use strip although I have never used it on a tuple (not even sure if you can) but I was hoping there is a more elegant way. Also I am using the sqlite3 module.
def search_db(self,ID,FName,LName):
#try:
FName +='%'
LName += '%'
self.cur.execute(("""SELECT FirstName FROM members WHERE FirstName LIKE '%s'\
AND LastName LIKE '%s'""") % (FName, LName))
value = (self.cur.fetchall())
print(value)
#except:
#print('failed')
cla = Database()
cla.search_db(1,'K','D')
You need to access the first element of the list, which is the tuple, then the first element of the tuple, so:
value[0][0]
In Python 2.7.1 I can create a named tuple:
from collections import namedtuple
Test = namedtuple('Test', ['this', 'that'])
I can populate it:
my_test = Test(this=1, that=2)
And I can print it like this:
print(my_test)
Test(this=1, that=2)
but why can't I print it like this?
print("my_test = %r" % my_test)
TypeError: not all arguments converted during string formatting
Edit:
I should have known to look at Printing tuple with string formatting in Python
Since my_test is a tuple, it will look for a % format for each item in the tuple. To get around this wrap it in another tuple where the only element is my_test:
print("my_test = %r" % (my_test,))
Don't forget the comma.
You can do this:
>>> print("my_test = %r" % str(my_test))
my_test = 'Test(this=1, that=2)'
It's unpacking it as 2 arguments. Compare with:
print("dummy1 = %s, dummy2 = %s" % ("one","two"))
In your case, try putting it in a tuple.
print("my_test = %r" % (my_test,))
The earlier answers are valid but here's an option if you don't care to print the name. It's a one-liner devised to pretty print only the contents of a named tuple of arbitrary length. Given a named tuple assigned to "named_tuple" the below yields a comma-delineated string of key=value pairs:
', '.join(['{0}={1}'.format(k, getattr(named_tuple, k)) for k in named_tuple._fields])
As now documented at 4.7.2. printf-style String Formatting, the % string formatting or interpolation operator is problematic:
The [printf-style string formatting operations] exhibit a variety of quirks that lead to a number of common errors (such as failing to display tuples and dictionaries correctly). Using the newer formatted string literals or the str.format() interface helps avoid these errors
So for example you can now do:
from collections import namedtuple
Test = namedtuple('Test', ['this', 'that'])
my_test = Test(this=1, that=2)
print("my_test = {0!r}".format(my_test))