Sequence

Posted on | Edited on | In | Comments:

Sequence

Sequence
iterable objects visited through index
  • __len__()
  • len()

Sequence's basic operation

Sequence objects have a method named __getitem__(self, key), so it can be visited by s[i].

1
2
b = b'ABCDEFG'
b[0] ==> 65

slice

The basic form of slice is s[i:j] and s[i:j:k]. slice object is used to save index information of slice, such as slice(start, stop, step). slice object has attributes such as '.start', '.stop' and '.step', method such as 'indice(len)' which return a tuple.

1
2
3
4
5
6
7
8
9
s[::-1] 	==> 'fedcba'

b[0:1] 		==> b'A'
b[0:len(b)] ==> b'ABCDEF'

slice_obj = slice(1, len(s), 2)
s[slice_obj]==> 'bdf'

slice_obj.indices(4)
1
2
3
s1 + s2
s1 += s2
s2 *= 2

Judge a object wehther or not exist in sequence s.

1
2
3
4
x in s
x not in s
s.count(x)
s.index(value[, start [, stop]])
1
2
sorted(iterable, key = None, reverse = False)
key = str.lower
1
2
3
4
len()
max()
min()
sum()
1
2
all(iterable)
any(iterable)

sequence unpacking

1
2
a, b = (1, 2)
sid, name, (chinese, math, english) = data

tuple variable * assign a number of variable to a tuple variable

1
first, *middles, last = range(10)

temporary variable_ obtain partial data

1
_, b, _ = (1, 2, 3)

tuple

define a tuple

  • x1, [x2, ..., xn]
  • (x1, [x2, ..., xn])
  • tuple()
  • tuple(iterable)
  • (1,)

list

define a list

  • [x1, [x2, ..., xn]]
  • list()
  • list(iterable)

basic operations

  • del s[index]
  • s[i:j] = x
  • dd s[i:j], equal as s[i:j] = []
  • s[i:j] = []

list's methods

  • s.append(x)
  • s.clear()
  • s.copy()
  • s.extend(t)
  • s.insert(i, x)
  • s.pop()
  • s.remove(x)
  • s.reverse()
  • s.sort()

list comprehension

1
2
3
[i**2 for i in range(10)]
[i for i in range(10) if i%2 == 0]
[(x, y, x*y) for x in range(1, 4) for y in range(1, 4) if x>= y]

string

1
2
ord('A')	==>	unicode
chr(65)		==> char
1
2
3
4
5
6
7
8
str.strip()
str.lstrip()
str.rstrip()
str.zfill(width)
str.center()
str.ljust()
str.rjust()
str.expandtabs()
1
2
3
4
5
6
7
8
9
10
test, find and replace

str.startwith()
str.endwith()
str.count()
str.index()
str.rindex()
str.find()
str.rfind()
str.replace()
1
2
3
4
5
6
str.split()			==>	list
str.rsplit()
str.partition(seq)	==>	(left, seq, right)
str.rpartition(seq)
str.splitlines()	==> list
str.join()			==> string
1
2
str.maketrans()
str.translate()
1
2
b.decode(encoding, errors)
s.encode(encoding = 'utf-8', errors = 'strict')

NOT SUGGESTING

1
string % (values)
1
'%(lang)s has %(num)03d quote types.' % {'lang':Python, 'num':2}

bytes and bytearray

  • bytes
  • bytearray
  • memoryview
1
b = s.encode()
Related Posts