python-2.x

问题 EDIT : Thank you for your kind replies on how to accomplish what I am trying to do, but the question is about WHY range().append() returns None if you try it in one step, and WHY it works if you two-step the procedure. Im trying to create a numerical list but with a twist. I don't want a couple of numbers at the beggining of my list: mlist = [0, 5, 6, 7, ...] So i thought to do the following: mlist = range(5,n+1).append(0) but silently fails because type(mlist) afterwards equals to NoneType ?

问题 Why does 4 < '3' return True in Python 2? Is it because when I place single quotes around a number Python sees it as a string and strings are bigger than numbers? 回答1: Yes, any number will be less than any string (including the empty string) in Python 2. In Python 3, you can't make arbitrary comparisons. You'll get a TypeError. From the link in eryksun's comment: if (PyNumber_Check(v)) vname = ""; else vname = v->ob_type->tp_name; if (PyNumber_Check(w)) wname = ""; else wname = w->ob_type->tp

问题 Is there any other argument than key , for example: value ? 回答1: Arguments of sort and sorted Both sort and sorted have three keyword arguments: cmp , key and reverse . L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*; cmp(x, y) -> -1, 0, 1 sorted(iterable, cmp=None, key=None, reverse=False) --> new sorted list Using key and reverse is preferred, because they work much faster than an equivalent cmp . key should be a function which takes an item and returns a value to

问题 Is there a known date/timeframe when python 2.7 will not be supported any more in favor of python 3? 回答1: As of 13 Apr 2014, from http://hg.python.org/peps/rev/76d43e52d978 (PEP 373, Python 2.7 Release Schedule): The End Of Life date (EOL, sunset date) for Python 2.7 has been moved five years into the future, to 2020. This decision was made to clarify the status of Python 2.7 and relieve worries for those users who cannot yet migrate to Python 3. See also PEP 466. 回答2: In May 2010, Word of

问题 Is there a known date/timeframe when python 2.7 will not be supported any more in favor of python 3? 回答1: As of 13 Apr 2014, from http://hg.python.org/peps/rev/76d43e52d978 (PEP 373, Python 2.7 Release Schedule): The End Of Life date (EOL, sunset date) for Python 2.7 has been moved five years into the future, to 2020. This decision was made to clarify the status of Python 2.7 and relieve worries for those users who cannot yet migrate to Python 3. See also PEP 466. 回答2: In May 2010, Word of

问题 I started by trying to store strings in sqlite using python, and got the message: sqlite3.ProgrammingError: You must not use 8-bit bytestrings unless you use a text_factory that can interpret 8-bit bytestrings (like text_factory = str). It is highly recommended that you instead just switch your application to Unicode strings. Ok, I switched to Unicode strings. Then I started getting the message: sqlite3.OperationalError: Could not decode to UTF-8 column 'tag_artist' with text 'Sigur Rós' when

问题 >>> from matplotlib import pyplot as plt Traceback (most recent call last): File "<pyshell#4>", line 1, in <module> from matplotlib import pyplot as plt File "C:\Python27\lib\site-packages\matplotlib\pyplot.py", line 24, in <module> import matplotlib.colorbar File "C:\Python27\lib\site-packages\matplotlib\colorbar.py", line 27, in <module> import matplotlib.artist as martist File "C:\Python27\lib\site-packages\matplotlib\artist.py", line 8, in <module> from transforms import Bbox,

问题 This question already has answers here : Why do integers in database row tuple have an 'L' suffix? (3 answers) Closed 5 years ago . If you've noticed, python adds an L on to the end of large exponent results like this: >>> 25 ** 25 88817841970012523233890533447265625L After doing some tests, I found that any number below 10 doesn't include the L . For example: >>> 9 ** 9 387420489 This was strange, so, why does this happen, is there any method to prevent it? All help is appreciated! 回答1:

问题 I know the flask function render_template . I have to give the file name of the template. But now I want to render the string of a template (that is the content of the template). That makes sense. but I don't want to explain now why. How can I render the text of a template simply? 回答1: You can use render_template_string: >>> from flask import render_template_string >>> render_template_string('hello {{ what }}', what='world') 'hello world' 回答2: you can use from_string template = "text {{ hello

问题 I know the flask function render_template . I have to give the file name of the template. But now I want to render the string of a template (that is the content of the template). That makes sense. but I don't want to explain now why. How can I render the text of a template simply? 回答1: You can use render_template_string: >>> from flask import render_template_string >>> render_template_string('hello {{ what }}', what='world') 'hello world' 回答2: you can use from_string template = "text {{ hello