Python Interview Questions FAQ - 2
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You would only use the Dictionary if you needed to map (or associate) meaningful keys to values, whereas a List only maps (or associates) positions (or indices) to values.
List comprehensions provide a concise way to create lists. Common applications are to make new lists where each element is the result of some operations applied to each member of another sequence or iterable, or to create a subsequence of those elements that satisfy a certain condition.
same as :
Python 3.3+ adds list.copy() method, which should be as fast as slicing:
The range() is the built-in function to be used for iterating the sequence of numbers.
Python supports six sequence types, they are:
- unicode strings
- range objects
You can use shell redirection while executing the python file.
The reversed() method returns an iterator that accesses the given sequence in the reverse order.
The Dogpile effect occurs when cache expires and websites are hit by numerous requests the same time. It is triggered because we allowed more than one request to execute the expensive query.
Dog pile effect can be prevented using semaphore lock. If value expired, first process acquires a lock and starts generating new value. All the subsequent requests check if lock is acquired and serve stale content. After new value is generated, lock is released.