The reason you need to use self. is because Python does not use the @ syntax to refer to instance attributes. Python decided to do methods in a way that makes the instance to which the method belongs be passed automatically, but not received automatically: the first parameter of methods is the instance the method … Read more
There are two types of site-packages directories, global and per user. Global site-packages (“dist-packages”) directories are listed in sys.path when you run: python -m site For a more concise list run getsitepackages from the site module in Python code: python -c ‘import site; print(site.getsitepackages())’ Caution: In virtual environments getsitepackages is not available with older versions … Read more
You can get the values as a list by doing: list(my_dataframe.columns.values) Also you can simply use (as shown in Ed Chum’s answer): list(my_dataframe)
To get a new reversed list, apply the reversed function and collect the items into a list: >>> xs = [0, 10, 20, 40] >>> list(reversed(xs)) [40, 20, 10, 0] To iterate backwards through a list: >>> xs = [0, 10, 20, 40] >>> for x in reversed(xs): … print(x) 40 20 10 0
is is identity testing, == is equality testing. what happens in your code would be emulated in the interpreter like this: >>> a=”pub” >>> b = ”.join([‘p’, ‘u’, ‘b’]) >>> a == b True >>> a is b False so, no wonder they’re not the same, right? In other words: a is b is the … Read more
This should be as simple as: with open(‘somefile.txt’, ‘a’) as the_file: the_file.write(‘Hello\n’) From The Documentation: Do not use os.linesep as a line terminator when writing files opened in text mode (the default); use a single ‘\n’ instead, on all platforms. Some useful reading: The with statement open() ‘a’ is for append, or use ‘w’ to … Read more
You cannot declare a variable or value as constant in Python. To indicate to programmers that a variable is a constant, one usually writes it in upper case: CONST_NAME = “Name” To raise exceptions when constants are changed, see Constants in Python by Alex Martelli. Note that this is not commonly used in practice. As … Read more
Python never implicitly copies objects. When you set dict2 = dict1, you are making them refer to the same exact dict object, so when you mutate it, all references to it keep referring to the object in its current state. If you want to copy the dict (which is rare), you have to do so … Read more
The special variable __file__ contains the path to the current file. From that we can get the directory using either pathlib or the os.path module. Python 3 For the directory of the script being run: import pathlib pathlib.Path(__file__).parent.resolve() For the current working directory: import pathlib pathlib.Path().resolve() Python 2 and 3 For the directory of the … Read more
What is the line? You can just have arguments on the next line without any problems: a = dostuff(blahblah1, blahblah2, blahblah3, blahblah4, blahblah5, blahblah6, blahblah7) Otherwise you can do something like this: if (a == True and b == False): or with explicit line break: if a == True and \ b == False: Check … Read more