This code will read the entire file into memory and remove all whitespace characters (newlines and spaces) from the end of each line: with open(filename) as file: lines = file.readlines() lines = [line.rstrip() for line in lines] If you’re working with a large file, then you should instead read and process it line-by-line: with open(filename) … Read more
Use the type() builtin function: >>> i = 123 >>> type(i) <type ‘int’> >>> type(i) is int True >>> i = 123.456 >>> type(i) <type ‘float’> >>> type(i) is float True To check if a variable is of a given type, use isinstance: >>> i = 123 >>> isinstance(i, int) True >>> isinstance(i, (float, str, … Read more
There are two built-in functions that help you identify the type of an object. You can use type() if you need the exact type of an object, and isinstance() to check an object’s type against something. Usually, you want to use isinstance() most of the times since it is very robust and also supports type … Read more
Use del and specify the index of the element you want to delete: >>> a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] >>> del a[-1] >>> a [0, 1, 2, 3, 4, 5, 6, 7, 8] Also supports slices: >>> del a[2:4] >>> a [0, 1, 4, 5, 6, 7, 8, … Read more
tl;dr: Because of different default settings in C++ requiring more system calls. By default, cin is synchronized with stdio, which causes it to avoid any input buffering. If you add this to the top of your main, you should see much better performance: std::ios_base::sync_with_stdio(false); Normally, when an input stream is buffered, instead of reading one … Read more
You need to double the {{ and }}: >>> x = ” {{ Hello }} {0} ” >>> print(x.format(42)) ‘ { Hello } 42 ‘ Here’s the relevant part of the Python documentation for format string syntax: Format strings contain “replacement fields” surrounded by curly braces {}. Anything that is not contained in braces is … Read more
You are running into the old problem with floating point numbers that not all numbers can be represented exactly. The command line is just showing you the full floating point form from memory. With floating point representation, your rounded version is the same number. Since computers are binary, they store floating point numbers as an … Read more
The len() function can be used with several different types in Python – both built-in types and library types. For example: >>> len([1, 2, 3]) 3
Note: This answer was intended for a very specific question. For most programmers coming here from a search engine, this is not the answer you are looking for. Typically you would structure your files into packages (see other answers) instead of modifying the search path. By default, you can’t. When importing a file, Python only … Read more
Use random.choice(): import random foo = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’] print(random.choice(foo)) For cryptographically secure random choices (e.g., for generating a passphrase from a wordlist), use secrets.choice(): import secrets foo = [‘battery’, ‘correct’, ‘horse’, ‘staple’] print(secrets.choice(foo)) secrets is new in Python 3.6. On older versions of Python you can use the random.SystemRandom class: import random … Read more