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Python Articles
Page 806 of 855
How to write inline if statement for print in Python?
Python provides two ways to write inline if statements. These are:1. if condition: statement2. s1 if condition else s2Note that second type of if cannot be used without an else. Now you can use these inline in a print statement as well. For example,a = True if a: print("Hello")This will give the output:Helloa = False print("True" if a else "False")This will give the output:False
Read MoreHow to use if...else statement at the command line in Python?
There are multiple ways in which you can use if else construct in the command line in python. For example, bash supports multiline statements, which you can use like:$ python -c ' > a = True > if a: > print("a is true") > 'This will give the output:a is trueIf you prefer to have the python statement in a single line, you can use the newline between the commands. For example,$ python -c $'a = Trueif a: print("a is true");'This will give the output:a is true
Read MoreWhere to put comments in an if...elif..else construct?
You can put comments anywhere in an if...elif...else statement, ie before each of these blocks or within each of these blocks. Note that you cannot put multiline comments before elif and else blocks though, as these comments are actually strings which imply a break in the whole construct. For example,# If check if True: # Another Comment style print("If block") # Else if statement elif False: # Another Comment style print("elif block") # Else else: # Another Comment style print("Else block")This will give the output:If block
Read MoreHow to comment each condition in a multi-line if statement in Python?
You can do this directly if you are surrounding your multiline if statements conditions in a parenthesis. For example,if (cond1 == 'val1' and cond2 == 'val2' and # Some comment cond3 == 'val3' and # Some comment cond4 == 'val4'):However, this is not possible if you try to do this without a parenthesis. For example, the following code will give an error:if cond1 == 'val1' and \ cond2 == 'val2' and \ # Some comment cond3 == 'val3' and \ # Some comment cond4 == 'val4':
Read MoreWhat is python .. ("dot dot") notation syntax?
There is no special .. ("dot dot") notation syntax in python. You can, however, see this in case of floats accessing their properties. For example,f = 1..__truediv__ # or 1..__div__ for python 2 print(f(8))This will give the output:0.125What we have is a float literal without the trailing zero, which we then access the __truediv__ method of. It's not an operator in itself; the first dot is part of the float value, and the second is the dot operator to access the object's properties and methods. This can also be achieved using:>>> f = 1. >>> f 1.0 >>> f.__truediv__
Read MoreWhat is the associativity of Python's ** operator?
From the Python docs:Operators in the same box group left to right (except for comparisons), including tests, which all have the same precedence and chain from left to right — see section Comparisons — and exponentiation, which groups from right to left).So the ** operator(exponentiation) is right to left associative. For example,2 ** 3 ** 4 will be evaluated as: (2 ** (3 ** 4))For example,print(2 ** 3 ** 0)This will give the output:2
Read MoreHow to put comments inside a Python dictionary?
You can put comments like you normally would anywhere in a python script. But note that you can only put single line comments using #. Multiline comments act like strings and you cannot put just a string in between definition of a dict. For example, the following declaration is perfectly valid:testItems = { 'TestOne': 'Hello', # 'TestTwo': None, }But the following is not:testItems = { 'TestOne': 'Hello', """ Some random multiline comment """ }
Read MoreCan you please explain Python dictionary memory usage?
The dictionary consists of a number of buckets. Each of these buckets containsthe hash code of the object currently stored (that is not predictable from the position of the bucket due to the collision resolution strategy used)a pointer to the key objecta pointer to the value objectThis sums up to at least 12 bytes on a 32bit machine and 24 bytes on a 64bit machine. The dictionary starts with 8 empty buckets. This is then resized by doubling the number of entries whenever its capacity is reached.
Read MoreHow to create Python dictionary from JSON input?
You can parse JSON files using the json module in Python. This module parses the json and puts it in a dict. You can then get the values from this like a normal dict. For example, if you have a json with the following content{ "id": "file", "value": "File", "popup": { "menuitem": [ {"value": "New", "onclick": "CreateNewDoc()"}, {"value": "Open", "onclick": "OpenDoc()"}, {"value": "Close", "onclick": "CloseDoc()"} ] } }You can load it in your python program and loop over ...
Read MoreHow to search Python dictionary for matching key?
If you have the exact key you want to find, then you can simply use the [] operator or get the function to get the value associated with this key. For example,Examplea = { 'foo': 45, 'bar': 22 } print(a['foo']) print(a.get('foo'))OutputThis will give the output:45 45ExampleIf you have a substring that you want to search in the dict, you can use substring search on the keys list and if you find it, use the value. For example,a = { 'foo': 45, 'bar': 22 } for key in a.keys(): if key.find('oo') > -1: print(a[key])OutputThis will give the output45
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