Python3 Basics - Revision history

Scott: /* Operations on Strings */

2020-01-30T19:11:01Z

Operations on Strings

← Older revision		Revision as of 19:11, 30 January 2020
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	"My name is {0}, my age is {1}".format(name, age)		"My name is {0}, my age is {1}".format(name, age)
	"My name is {name}, my age is {age}".format(name="Bill", age=28)		"My name is {name}, my age is {age}".format(name="Bill", age=28)
			date_info = {'year': "2020", 'month': "01", 'day': "01"}
			track_info = {'artist': "Beethoven", 'title': 'Symphony No 5'}
			filename = "{year}-{month}-{day}-{artist}-{title}.txt".format(
			date_info, track_info ) # '2020-01-01-Beethoven-Symphony No 5.txt'
	S = "abcdef"		S = "abcdef"
	S[2:4] # 'cd' substring		S[2:4] # 'cd' substring

2014-01-14T18:42:32Z

Operations on Strings

← Older revision		Revision as of 18:42, 14 January 2014
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	== Operations on Strings ==		== Operations on Strings ==
	<source lang="python">		<source lang="python">
	# formatted positional variable interpolation		# formatted positional variable interpolation (deprecated)
	'My name is %s, my age is %d' % (name, age)		'My name is %s, my age is %d' % (name, age)
	# formatted dictionary-based variable interpolation		# formatted dictionary-based variable interpolation (deprecated)
	'My name is %(name)s, my age is %(age)d' % {'name': name, 'age', age}		'My name is %(name)s, my age is %(age)d' % {'name': name, 'age', age}
	# number formats		# number formats (deprecated)
	"file_%03d.txt" % 2 # "file_002.txt"		"file_%03d.txt" % 2 # "file_002.txt"
	"5-day increase: %3.1f%%" % 2.6453 # "5-day increase: 2.6%"		"5-day increase: %3.1f%%" % 2.6453 # "5-day increase: 2.6%"
			# Python 3 string formatting
			"My name is {0}, my age is {1}".format(name, age)
			"My name is {name}, my age is {age}".format(name="Bill", age=28)
	S = "abcdef"		S = "abcdef"
	S[2:4] # 'cd' substring		S[2:4] # 'cd' substring

2014-01-14T18:29:27Z

Expressions

← Older revision		Revision as of 18:29, 14 January 2014
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	x and y # returns y if x is true, otherwise returns x		x and y # returns y if x is true, otherwise returns x
	x or y # returns x if x is true, otherwise returns y		x or y # returns x if x is true, otherwise returns y
			1/2 # float (0.5)
			1//2 # int (0)
	</source>		</source>

2014-01-14T18:00:13Z

Dictionaries

← Older revision		Revision as of 18:00, 14 January 2014
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	'a' in x # True (in matches keys)		'a' in x # True (in matches keys)
	x.copy() # {'a': 1, 'b': 2} (shallow copy)		x.copy() # {'a': 1, 'b': 2} (shallow copy)
	x.items() # dict_items([('a', 1), ('b', 2)])		x.items() # dict_items([('a', 1), ('b', 2)]) (can iterate with for)
	x.keys() # dict_keys(['a', 'b'])		x.keys() # dict_keys(['a', 'b']) (can iterate with for)
	sorted(x.keys()) # ['a', 'b']		sorted(x.keys()) # ['a', 'b']
	x.values() # dict_values([1, 2])		x.values() # dict_values([1, 2]) (can iterate with for)
	x['a'] # 1		x['a'] # 1
	x.get('a') # 1		x.get('a') # 1
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	x.pop('a') # x == {'b': 2}		x.pop('a') # x == {'b': 2}
	x.popitem() # ('a', 1), x == {'b':2} (item randomly selected)		x.popitem() # ('a', 1), x == {'b':2} (item randomly selected)
	~~TODO: iteritems, iterkeys, itervalues~~
	</source>		</source>

2014-01-14T17:59:26Z

Dictionaries

2014-01-14T17:55:48Z

Object Types

← Older revision		Revision as of 17:55, 14 January 2014
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	* <code>set</code>		* <code>set</code>
	* <code>dict</code>		* <code>dict</code>
	* Others: views, iterators, type, function, classobj, instance		* Others: dictionary views, iterators, type, function, classobj, instance
	<source lang="python">		<source lang="python">
	type(object) # returns the type of object		type(object) # returns the type of object

2014-01-14T17:54:57Z

Object Types

← Older revision		Revision as of 17:54, 14 January 2014
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	* <code>set</code>		* <code>set</code>
	* <code>dict</code>		* <code>dict</code>
	* Others: type, function, classobj, instance		* Others: views, iterators, type, function, classobj, instance
	<source lang="python">		<source lang="python">
	type(object) # returns the type of object		type(object) # returns the type of object

2014-01-14T17:49:25Z

Control Flow

← Older revision		Revision as of 17:49, 14 January 2014
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	<source lang="python">		<source lang="python">
	for x in range(5,25,5): ~~# use xrange() for better performance~~		for x in range(5,25,5):
	print(x, end=" ") # 5 10 15 20		print(x, end=" ") # 5 10 15 20
	</source>		</source>

2014-01-14T17:34:04Z

Control Flow

← Older revision		Revision as of 17:34, 14 January 2014
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	<source lang="python">		<source lang="python">
	for x in range(5,25,5): # use xrange() for better performance		for x in range(5,25,5): # use xrange() for better performance
	print(x,) # 5 10 15 20		print(x, end=" ") # 5 10 15 20
	</source>		</source>

2014-01-14T17:29:04Z

← Older revision		Revision as of 17:29, 14 January 2014
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			== What's new in Python 3 ==
			http://docs.python.org/3.0/whatsnew/3.0.html

	== Program Structure ==		== Program Structure ==
	* # for comments		* # for comments