call a method using a period . struture like:
<objectName>.<methodName>(list of arguments, if any)
# Reversing a list L = [1, 2, 3, 4, 5] L.reverse() print(L)f [5, 4, 3, 2, 1]
# Some String Methods print(‘piece of cake‘.startwith(‘pie‘)) print(‘red‘.startwith(‘blue‘)) True False
Many Methds:
Lists
These methods do not alter the list:
list.index(X): find X in the list. eg. list[i] == X , return i , i is lowest. if X doesn‘t exist in the list, return ValueError
list.count(X): returns a count of how many times X appears in the list.
These methods alter the list:
- list.append(X) adds X to the end of the list
- list.insert(i, X) adds X at position i
- list.extend(L) adds a list L of items to the end.
- list.remove(X) removes the first occurence of X.
- list.pop(i) deletes & returns item list[i], while list.pop() deletes & returns the last item
- del list[i] deletes the ith item of list
- list.reverse() reverses the list
- list.sort() sorts the list
# Codeing Exercise: The Replacements #using index and oter list methods, write a function replace(list, X, Y) which replaces all occurrences of X in list with Y. #e.g. if L = {3, 1, 4, 1, 5, 9} then replace (L, 1, 7) would be change the contents of to [3, 7, 4, 7, 5, 9]. def replace(list, X, Y): for i in range(0, list.count(X)): list.insert(list.index(X), Y) list.remove(X) print(list)
Stings
S in T is a bool indicating whether string S is substring of string T
S.index(T) finds the first index of S where T is sustring
时间: 2024-10-12 09:15:08