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Python Articles
Page 821 of 855
What is the correct way to define class variables in Python?
Class variables are variables that are declared outside the__init__method. These are static elements, meaning, they belong to the class rather than to the class instances. These class variables are shared by all instances of that class. Example code for class variables Exampleclass MyClass: __item1 = 123 __item2 = "abc" def __init__(self): #pass or something elseYou'll understand more clearly with more code −class MyClass: stat_elem = 456 def __init__(self): self.object_elem = 789 c1 = MyClass() c2 = MyClass() # Initial values of both elements >>> print c1.stat_elem, c1.object_elem 456 ...
Read MoreHow to read and write unicode (UTF-8) files in Python?
The io module is now recommended and is compatible with Python 3's open syntax: The following code is used to read and write to unicode(UTF-8) files in PythonExampleimport io with io.open(filename,'r',encoding='utf8') as f: text = f.read() # process Unicode text with io.open(filename,'w',encoding='utf8') as f: f.write(text)
Read MoreHow to get the number of capture groups in Python regular expression?
The following code gets the number of captured groups using Python regex in given stringExampleimport re m = re.match(r"(\d)(\d)(\d)", "632") print len(m.groups())OutputThis gives the output3
Read MoreHow to write Python regular expression to get all the anchor tags in a webpage?
The following code extracts all tags in the given stringExampleimport re rex = re.compile(r'[\]') l = "this is text1 hi this is text2" print rex.findall(l)Output['', '']
Read MoreHow to use wildcard in Python regular expression?
The following code uses the Python regex .()dot character for wildcard which stands for any character other than newline.Exampleimport re rex = re.compile('th.s') l = "this, thus, just, then" print rex.findall(l)OutputThis gives the output['this', 'thus']
Read MoreHow to find all adverbs and their positions in a text using python regular expression?
As per Python documentationIf one wants more information about all matches of a pattern than the matched text, finditer() is useful as it provides match objects instead of strings. If one was a writer who wanted to find all of the adverbs and their positions in some text, he or she would use finditer() in the following manner −>>> text = "He was carefully disguised but captured quickly by police." >>> for m in re.finditer(r"\w+ly", text): ... print('%02d-%02d: %s' % (m.start(), m.end(), m.group(0))) 07-16: carefully 40-47: quickly
Read MoreHow to extract numbers from text using Python regular expression?
If we want to extract all numbers/digits individually from given text we use the following regexExampleimport re s = '12345 abcdf 67' result=re.findall(r'\d', s) print resultOutput['1', '2', '3', '4', '5', '6', '7']If we want to extract groups of numbers/digits from given text we use the following regexExampleimport re s = '12345 abcdf 67' result=re.findall(r'\d+', s) print resultOutput['12345', '67']
Read MoreHow to write a Python regular expression to match multiple words anywhere?
The following code using Python regex matches the given multiple words in the given stringExampleimport re s = "These are roses and lilies and orchids, but not marigolds or .." r = re.compile(r'\broses\b | \bmarigolds\b | \borchids\b', flags=re.I | re.X) print r.findall(s)OutputThis gives the output['roses', 'orchids', 'marigolds']
Read MoreHow to find and replace within a text file using Python?
The following code does the replacement in the given text file. After the replacement, the text is written to a new text file 'bar.txt'Examplef1 = open('foo.txt', 'r') f2 = open('bar.txt', 'w') for line in f1: print line f2.write(line.replace('Poetry', 'Prose')) f2 = open('bar.txt', 'r') for line in f2: print line, f1.close() f2.close()OutputThis gives the outputPoetry is often considered the oldest form of literature. Poetry today is usually written down, but is still sometimes performed. Prose is often considered the oldest form of literature. Prose today is usually written down, but is still sometimes performed.
Read MoreWhat are Python modules for date manipulation?
There are many modules available in both the standard library and the PiPy repository for date manipulation. The most popular among these libraries are the following(in no particular order) −datetime (Standard library) − The datetime module supplies classes for manipulating dates and times in both simple and complex ways. While date and time arithmetic is supported, the focus of the implementation is on efficient attribute extraction for output formatting and manipulation.time(Standard library) − This module provides various time-related functions. Although this module is always available, not all functions are available on all platforms. Most of the functions defined in this ...
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