The *args and **kwargs is a common idiom to allow arbitrary number of arguments to functions as described in the section more on defining functions in the Python documentation. The *args will give you all function parameters as a tuple: def foo(*args): for a in args: print(a) foo(1) # 1 foo(1,2,3) # 1 # 2 … Read more
This delays for 2.5 seconds: import time time.sleep(2.5) Here is another example where something is run approximately once a minute: import time while True: print(“This prints once a minute.”) time.sleep(60) # Delay for 1 minute (60 seconds).
To select rows whose column value equals a scalar, some_value, use ==: df.loc[df[‘column_name’] == some_value] To select rows whose column value is in an iterable, some_values, use isin: df.loc[df[‘column_name’].isin(some_values)] Combine multiple conditions with &: df.loc[(df[‘column_name’] >= A) & (df[‘column_name’] <= B)] Note the parentheses. Due to Python’s operator precedence rules, & binds more tightly than … Read more
new_list = my_list doesn’t actually create a second list. The assignment just copies the reference to the list, not the actual list, so both new_list and my_list refer to the same list after the assignment. To actually copy the list, you have several options: You can use the builtin list.copy() method (available since Python 3.3): … Read more
append appends a specified object at the end of the list: >>> x = [1, 2, 3] >>> x.append([4, 5]) >>> print(x) [1, 2, 3, [4, 5]] extend extends the list by appending elements from the specified iterable: >>> x = [1, 2, 3] >>> x.extend([4, 5]) >>> print(x) [1, 2, 3, 4, 5]
Arguments are passed by assignment. The rationale behind this is twofold: the parameter passed in is actually a reference to an object (but the reference is passed by value) some data types are mutable, but others aren’t So: If you pass a mutable object into a method, the method gets a reference to that same … Read more
Actually, this is not a design flaw, and it is not because of internals or performance. It comes simply from the fact that functions in Python are first-class objects, and not only a piece of code. As soon as you think of it this way, then it completely makes sense: a function is an object … Read more
if not a: print(“List is empty”) Using the implicit booleanness of the empty list is quite pythonic.
Use the + operator to combine the lists: listone = [1, 2, 3] listtwo = [4, 5, 6] joinedlist = listone + listtwo Output: >>> joinedlist [1, 2, 3, 4, 5, 6]
It used to be a required part of a package (old, pre-3.3 “regular package”, not newer 3.3+ “namespace package”). Here’s the documentation. Python defines two types of packages, regular packages and namespace packages. Regular packages are traditional packages as they existed in Python 3.2 and earlier. A regular package is typically implemented as a directory … Read more