Summary¶
This chapter introduced a lot of new ideas. The following summary may prove helpful in remembering what you learned.
- indexing (
[]
) - Access a single character in a string using its position (starting from
0), or a single item from a list. Example:
'This'[2]
evaluates to'i'
. Example:[10, 20, 'hello'][1]
evaluates to20
- length function (
len
) - Returns the number of characters in a string or a list. Example:
len('happy')
evaluates to5
. Example:len([10, 20 'hello'])
evaluates to 3 - slicing (
[:]
) - A slice is a substring of a string or a list. Example:
'bananas and cream'[3:6]
evaluates toana
(so does'bananas and cream'[1:4]
). Example:[10, 20, 'hello', 'goodbye'][1:3]
evaluates to[20, 'hello']
- string comparison (
>, <, >=, <=, ==, !=
) - The six common comparision operators work with strings, evaluating according to
lexigraphical order. Examples:
'apple' < 'banana'
evaluates toTrue
.'Zeta' < 'Appricot'
evaluates toFalse
.'Zebra' <= 'aardvark'
evaluates toTrue
because all upper case letters precede lower case letters. - in and not in operator (
in
,not in
) - The
in
operator tests whether one string is contained inside another string. Examples:'heck' in "I'll be checking for you."
evaluates toTrue
.'cheese' in "I'll be checking for you."
evaluates toFalse
. - collection data type
- A data type in which the values are made up of components, or elements, that are themselves values.
- dot notation
- Use of the dot operator,
.
, to access methods and attributes of an object. - immutable
- A compound data type whose elements can not be assigned new values.
- index
- A variable or value used to select a member of an ordered collection, such as a character from a string, or an element from a list.
- whitespace
- Any of the characters that move the cursor without printing visible
characters. The constant
string.whitespace
contains all the white-space characters. - aliases
- Multiple variables that contain references to the same object.
- clone
- To create a new object that has the same value as an existing object. Copying a reference to an object creates an alias but doesn’t clone the object.
- delimiter
- A character or string used to indicate where a string should be split.
- element
- One of the values in a list (or other sequence). The bracket operator selects elements of a list.
- mutable data type
- A data type in which the elements can be modified. All mutable types are compound types. Lists are mutable data types; strings are not.
- object
- A thing to which a variable can refer.