Python

I/O Print

Python print/print() is very powerful... taking styling from C string formating and adding some of it's own features; allowing for deeper functionality. Pull up PyDocs and reference Py2 and Py3 print, %, and formatting.

Note: Python2 and Python3 print statement/function automatically creates a newline. We can get around this if needed.

Python 2 Basic:

print "hello" # print statement only valid in Py2
print 1+1
print 'Hello' + 'world'
print('Hello' , 'World') # print function valid in both Py2 and Py3 (use this)

# Printing without newline, still has space seperating though
print "First statement ",
print "%s" % ("Second statement"),
print "Third statement"
# Output: 'First statement Second statement Third statement'

Python 3 Basic:

print("hello")
print(1+1)
print('Hello' + 'World')
print('Hello' , 'World')

# Printing without newline
print("First statement ", end=" ")
print("{}".format("Second statement"), end="")
print("Third statement")
# Output: 'First statement  Second statementThird statement'

% Formatting

% formatting follows C style and is being phased out. It is highly recommend to use .format()… but have practice with both!

​# Basic Positional Formatting
print "%s World!" % "Hello"
'Hello World!'

# Basic Positional Formatting
print "%s %s!" % ("Hello", "World")
'Hello World!'

# Padding 10 left
print '%10s' % ('test',)
'      test'

# Negative Padding (10 right)
print '%-10s %s' % ('test', 'next word')
'test       next word'

# Truncating Long Strings
print '%.5s' % ('what in the world',)
'what '

# Truncating and padding
print '%10.5s' % ('what in the world',)
'     what'

# Numbers
print '%d' % (50,)
50

# Floats
print '%f' % (3.123513423532432)
3.123513

# Padding numbers
print '%4d' % (50,)
  50

# Padding Floating Points/precision
print '%06.2f' % (3.141592653589793,)
003.14

# Name Placeholders
things = {'car': 'BMW E30', 'motorcycle': 'Harley FXDX'}
print 'My fav car %(car)s and motorcycle %(motorcycle)s' % things
'My fav car BMW E30 and motorcycle Harley FXDX'

.format()

Format() is the latest formatting functionality. PEP8 highly encourages the use of .format() whenever possible. .format() includes most of the previous functionality with a ton of added functionality as well. Below is just SOME of the built in .format() functionality. Keep in mind, you can create custom functionality with .format(). Take a look at the docs and below and experiment!

​# Basic Positional Formatting
print('{} {}!'.format('Hello', 'World'))
'Hello World!'

# Basic Positional Formatting
print("{!s} {!s}".format("Hello", "World"))
'Hello World!'

# Actual Positional Formatting
# EXCLUSIVE
print('{1} {0}!'.format('World', 'Hello'))
'Hello World!'

# Padding 10 left
print('{:>10}'.format('test'))
'      test'

# Negative Padding 10 right
print('{:<10}'.format('test'))
'test      '

# Changing Padding Character
# EXCLUSIVE
print('{:_>10}'.format('test'))
'______test'

# Center Align
# EXCLUSIVE
print('{:_^10}'.format('test'))
'___test___'

# Truncating Long Strings
print('{:.5}'.format('what in the world'))
'what '

# Truncating and padding
print('{:10.5}'.format('what in the world'))
'     what'

# Numbers
print('{:d}'.format(50))
50

# Floats
print('{:f}'.format(3.123513423532432))
3.123513

# Padding numbers
print('{:4d}'.format(50))
  50

# Padding Floating Points/precision
print('{:06.2f}'.format(3.141592653589793))
003.14

# Name Placeholders
things = {'car': 'BMW E30', 'motorcycle': 'Harley FXDX'}
print('My favorite car is a {car} and motorcycle {motorcycle}'.format(**things))
'My fav car BMW E30 and motorcycle Harley FXDX'


# Date and Time
# EXCLUSIVE
from datetime import datetime
print('{:%Y-%m-%d %H:%M}'.format(datetime(2017, 10, 17, 10, 45)))
2017-10-17 10:45


#Variables
nBalloons = 8
print("Sammy has {} balloons today!".format(nBalloons))

Output
Sammy has 8 balloons today!


sammy = "Sammy has {} balloons today!"
nBalloons = 8
print(sammy.format(nBalloons))

Output
Sammy has 8 balloons today!

Continue to Performance Lab: 3A