Boston Python Workshop 3/Data types
Numbers: integers and floats
- Integers don't have a decimal place.
- Floats have a decimal place.
>>> type(1) <type 'int'> >>> type(1.0) <type 'float'>
Math: addition, subtraction, multiplication
addition: 2 + 2
subtraction: 0 - 2
multiplication: 2 * 3
Math: division
>>> 4 / 2 2 >>> 1 / 2 0
- Integer division produces an integer. You need a number that knows about the decimal point to get a decimal out of division:
>>> 1.0 / 2 0.5 >>> float(1) / 2 0.5
Strings
- String are surrounded by quotes.
- Use triple-quotes (""") to create whitespace-preserving multi-line strings.
>>> "Hello" 'Hello'
>>> print """In 2009, ... The monetary component of the Nobel Prize ... was US $1.4 million.""" In 2009, The monetary component of the Nobel Prize was US $1.4 million.
>>> type("Hello") <type 'str'>
String concatenation with '+': "Hello" + "World"
Printing strings with '+': print "Hello" + "World"
Printing strings with ',': print "Hello", "World", 1
Booleans
- There are two booleans,
True
andFalse
. - Use booleans to make decisions.
>>> type(True) <type 'bool'> >>> type(False) <type 'bool'>
Containment with 'in' and 'not in'
<pr> >>> "H" in "Hello" True >>> "a" not in ["a", "b", "c"] False
Equality
==
tests for equality!=
tests for inequality<
,<=
,>
, and>=
have the same meaning as in math class.
>>> 0 == 0 True >>> 0 == 1 False
"a" != "a"
"a" != "A"
Use with if/else blocks
- When Python encounters the
if
keyword, it evaluates the expression following the keyword and before the colon. If that expression isTrue
, Python executes the code in the indented code block under the if line. If that expression isFalse
, Python skips over the code block.
temperature = 32 if temperature > 60 and temperature < 75: print "It's nice and cozy in here!" else: print "Too extreme for me."