Pythonメモ

str = 'Spam'
str[0]   # S
str[-1]  # m
str[1:3] # pa
str[1:]  # pam
str[:3]  # Spa
str[:-1] # Spa
str[:]   # Spam

str = 'abcdefghij'
str[1:9:2]  # bdfh
str[5:1:-1] # fedc
str[::-1]   # jihgfedcba

len('abc')      # 3
len([1,2,3,4])  # 4

matrix = [[1, 2, 3],
          [4, 5, 6],
          [7, 8, 9]]
col2 = [row[1] for row in matrix]
col2
# [2, 5, 8]

tuple = (1, 2, 3, 4)
tuple[1] = 5
# TypeError: 'tuple' object does not support item assignment
tuple = (1,)

dir('string')
# ['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill']
help('string'.index)
# Help on built-in function index:
#
# index(...)
#     S.index(sub [,start [,end]]) -> int
#
#     Like S.find() but raise ValueError when the substring is not found.

print 'a\nb\tc'
# a
# b   c

a = [1, 2, 3, 4, 5]

# 特定の要素が含まれているかどうかの確認
3 in a  # => True
6 in a  # => False

# リスト内包表記
[x**2 for x in a] # => [1, 4, 9, 16, 25]