In [1]:

    

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
%matplotlib inline
from pandas import DataFrame, Series
from numpy.random import randn


    

In [2]:

    

a = 'this is a string'
b = 'this is another string'
a + b


    

    
Out[2]:





'this is a stringthis is another string'

In [3]:

    

template = '%.2f %s are worth $%d'
template % (4.5560, 'Argentine Pesos', 1)


    

    
Out[3]:





'4.56 Argentine Pesos are worth $1'

In [4]:

    

template % (3.3333, a + b, 2)


    

    
Out[4]:





'3.33 this is a stringthis is another string are worth $2'

In [5]:

    

True and True


    

    
Out[5]:





True

In [6]:

    

False or True


    

    
Out[6]:





True

In [7]:

    

a = [1, 2, 3]
if a:
    print 'I found something'


    

    




I found something

In [8]:

    

b = []
if not b:
    print 'Empty!'


    

    




Empty!

In [9]:

    

bool([]), bool([1, 2, 3])


    

    
Out[9]:





(False, True)

In [10]:

    

bool('Hello world!'), bool('')


    

    
Out[10]:





(True, False)

In [11]:

    

bool(0), bool(1)


    

    
Out[11]:





(False, True)

In [12]:

    

s = '3.14159'
fval = float(s)
type(fval)


    

    
Out[12]:





float

In [13]:

    

int(fval)


    

    
Out[13]:





3

In [14]:

    

bool(fval)


    

    
Out[14]:





True

In [15]:

    

bool(0)


    

    
Out[15]:





False

In [16]:

    

a = None
a is None


    

    
Out[16]:





True

In [17]:

    

b = 5
b is not None


    

    
Out[17]:





True

In [18]:

    

def add_and_maybe_multiply(a, b, c=None):
    result = a + b
    
    if c is not None:
        result = result * c

    return result


    

In [20]:

    

from datetime import datetime, date, time
dt = datetime(2011, 10, 29, 20, 30, 21)

dt.day


    

    
Out[20]:





29

In [21]:

    

dt.minute


    

    
Out[21]:





30

In [22]:

    

dt.date()


    

    
Out[22]:





datetime.date(2011, 10, 29)

In [23]:

    

dt.time()


    

    
Out[23]:





datetime.time(20, 30, 21)

In [24]:

    

dt.strftime('%m/%d/%Y %H:%M')


    

    
Out[24]:





'10/29/2011 20:30'

In [25]:

    

datetime.strptime('20091031', '%Y%m%d')


    

    
Out[25]:





datetime.datetime(2009, 10, 31, 0, 0)

In [26]:

    

dt.replace(minute=0, second=0)


    

    
Out[26]:





datetime.datetime(2011, 10, 29, 20, 0)

In [28]:

    

dt2 = datetime(2011, 11, 15, 22, 30)
delta = dt2 - dt
delta


    

    
Out[28]:





datetime.timedelta(17, 7179)

In [29]:

    

type(delta)


    

    
Out[29]:





datetime.timedelta

In [30]:

    

dt


    

    
Out[30]:





datetime.datetime(2011, 10, 29, 20, 30, 21)

In [31]:

    

dt + delta


    

    
Out[31]:





datetime.datetime(2011, 11, 15, 22, 30)

In [32]:

    

x=-1


    

In [33]:

    

if x < 0:
    print 'It"s negative'


    

    




It"s negative

In [34]:

    

def px(x):
    if x < 0:
        print 'It"s negative'
    elif x == 0:
        print 'Equal to zero'
    elif 0 < x < 5:
        print 'Positive but smaller than 5'
    else:
        print 'Positive and larger than or equal to 5'


    

In [35]:

    

px(x)


    

    




It"s negative

In [36]:

    

px(3)


    

    




Positive but smaller than 5

In [37]:

    

px(10)


    

    




Positive and larger than or equal to 5

In [38]:

    

px(0)


    

    




Equal to zero

In [40]:

    

a = 5; b = 7
c = 8; d = 4
if a < b or c > d:
    print 'Made it'


    

    




Made it

In [41]:

    

def mysum(seq):
    total = 0
    for value in seq:
        if value is None:
            continue
        total += value
    return total


    

In [42]:

    

mysum([1, 2, None, 4, None, 5])


    

    
Out[42]:





12

In [44]:

    

def mysum5(seq):
    total_until_5 = 0
    for value in seq:
        if value == 5:
            break
        total_until_5 += value
    return total_until_5


    

In [45]:

    

mysum5([1, 2, 0, 4, 6, 5, 2, 1])


    

    
Out[45]:





13

In [46]:

    

x = 256
total = 0
while x > 0:
    if total > 500:
        break
    total += x
    x = x // 2


    

In [47]:

    

total


    

    
Out[47]:





504

In [48]:

    

def f(x, y, z):
    # TODO: 实现这个函数！
    pass


    

In [49]:

    

float('1.2345')


    

    
Out[49]:





1.2345

In [50]:

    

float('som')


    

    




---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-50-b53cdacc4d9a> in <module>()
----> 1 float('som')

ValueError: could not convert string to float: som

In [55]:

    

def attempt_float(x):
    try:
        return float(x)
    except ValueError:
        return x


    

In [52]:

    

attempt_float('1.2345')


    

    
Out[52]:





1.2345

In [53]:

    

attempt_float('som')


    

    
Out[53]:





'som'

In [54]:

    

float(1, 2)


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-54-242066800d89> in <module>()
----> 1 float(1, 2)

TypeError: float() takes at most 1 argument (2 given)

In [56]:

    

attempt_float((1, 2))


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-56-9bdfd730cead> in <module>()
----> 1 attempt_float((1, 2))

<ipython-input-55-84efde0a7059> in attempt_float(x)
      1 def attempt_float(x):
      2     try:
----> 3         return float(x)
      4     except ValueError:
      5         return x

TypeError: float() argument must be a string or a number

In [57]:

    

def attempt_float(x):
    try:
        return float(x)
    except (TypeError, ValueError):
        return x


    

In [58]:

    

f = open('ch13testfinally.txt', 'w')

try:
    f.write("akakakak")
finally:
    f.close()


    

In [59]:

    

!cat ch13testfinally.txt


    

    




akakakak

In [60]:

    

f = open('ch13else.txt', 'w')

try:
    f.write('bkbkbkbkbk')
except:
    print 'Failed'
else:
    print 'Succeeded'
finally:
    f.close()


    

    




Succeeded

In [61]:

    

!cat ch13else.txt


    

    




bkbkbkbkbk

In [62]:

    

range(10)


    

    
Out[62]:





[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

In [63]:

    

range(0, 20, 2)


    

    
Out[63]:





[0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

In [65]:

    

val = 0
seq = [1, 2, 3, 4]
for i in range(len(seq)):
    val += seq[i]
val


    

    
Out[65]:





10

In [66]:

    

sum = 0
for i in xrange(10000):
    # %是求模运算符
    if i % 3 == 0 or i % 5 == 0:
        sum += i
sum


    

    
Out[66]:





23331668

In [67]:

    

x = 5
'Non-negative' if x >= 0 else 'Negative'


    

    
Out[67]:





'Non-negative'

In [68]:

    

tup = 4, 5, 6
tup


    

    
Out[68]:





(4, 5, 6)

In [69]:

    

nested_tup = (4, 5, 6), (7, 8)
nested_tup


    

    
Out[69]:





((4, 5, 6), (7, 8))

In [70]:

    

tuple([4, 0, 2])


    

    
Out[70]:





(4, 0, 2)

In [72]:

    

tup = tuple('string')
tup


    

    
Out[72]:





('s', 't', 'r', 'i', 'n', 'g')

In [73]:

    

tup[0]


    

    
Out[73]:





's'

In [74]:

    

tup = tuple(['foo', [1, 2], True])
tup[2] = False


    

    




---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-74-692985e84db1> in <module>()
      1 tup = tuple(['foo', [1, 2], True])
----> 2 tup[2] = False

TypeError: 'tuple' object does not support item assignment

In [75]:

    

tup[1].append(3)
tup


    

    
Out[75]:





('foo', [1, 2, 3], True)

In [76]:

    

(4, None, 'foo') + (6, 0) + ('bar',)


    

    
Out[76]:





(4, None, 'foo', 6, 0, 'bar')

In [77]:

    

('foo', 'bar') * 4


    

    
Out[77]:





('foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'bar')

In [78]:

    

tup = (4, 5, 6)
a, b, c = tup


    

In [79]:

    

b


    

    
Out[79]:





5

In [80]:

    

tup = 4, 5, (6, 7)
a, b, (c, d) = tup
d


    

    
Out[80]:





7

In [82]:

    

b, a = a, b
b


    

    
Out[82]:





5

In [83]:

    

seq = [(1, 2, 3), (4, 5, 6), (7, 8, 9)]
for a, b, c in seq:
    pass


    

In [85]:

    

a = (1, 2, 2, 2, 3, 4, 2)
a.count(2)


    

    
Out[85]:





4

In [88]:

    

for x in a:
    print str(x) + ','


    

    




1,
2,
2,
2,
3,
4,
2,

In [89]:

    

a_list = [2, 3, 7, None]
tup = ('foo', 'bar', 'baz')
b_list = list(tup)
b_list


    

    
Out[89]:





['foo', 'bar', 'baz']

In [90]:

    

b_list[1] = 'peekaboo'
b_list


    

    
Out[90]:





['foo', 'peekaboo', 'baz']

In [91]:

    

b_list.append('dwarf')
b_list


    

    
Out[91]:





['foo', 'peekaboo', 'baz', 'dwarf']

In [95]:

    

tup + ('x',)


    

    
Out[95]:





('foo', 'bar', 'baz', 'x')

In [96]:

    

b_list.insert(1, 'red')
b_list


    

    
Out[96]:





['foo', 'red', 'peekaboo', 'baz', 'dwarf']

In [97]:

    

b_list.pop(2)


    

    
Out[97]:





'peekaboo'

In [98]:

    

b_list


    

    
Out[98]:





['foo', 'red', 'baz', 'dwarf']

In [99]:

    

b_list.append('foo')
b_list.remove('foo')
b_list


    

    
Out[99]:





['red', 'baz', 'dwarf', 'foo']

In [100]:

    

'dwarf' in b_list


    

    
Out[100]:





True

In [102]:

    

[4, None, 'foo'] + [7, 8, (2, 3)] + ['x']


    

    
Out[102]:





[4, None, 'foo', 7, 8, (2, 3), 'x']

In [103]:

    

x = [4, None, 'foo']
x.extend([7, 8, (2, 3)])


    

    
Out[103]:





[4, None, 'foo', 7, 8, (2, 3)]

In [104]:

    

everything = []
for chunk in [b_list, x]:
    everything.extend(chunk)
everything


    

    
Out[104]:





['red', 'baz', 'dwarf', 'foo', 4, None, 'foo', 7, 8, (2, 3)]

In [106]:

    

everything = []
for chunk in [b_list, x]:
    everything = everything + chunk
everything


    

    
Out[106]:





['red', 'baz', 'dwarf', 'foo', 4, None, 'foo', 7, 8, (2, 3)]

In [107]:

    

a = [7, 2, 5, 1, 3]
a.sort()
a


    

    
Out[107]:





[1, 2, 3, 5, 7]

In [108]:

    

b = ['saw', 'small', 'He', 'foxes', 'six']
b.sort(key=len)
b


    

    
Out[108]:





['He', 'saw', 'six', 'small', 'foxes']

In [109]:

    

import bisect
c = [1, 2, 2, 2, 3, 4, 7]
bisect.bisect(c, 2)


    

    
Out[109]:





4

In [110]:

    

bisect.bisect(c, 5)


    

    
Out[110]:





6

In [113]:

    

bisect.insort(c, 6)
c


    

    
Out[113]:





[1, 2, 2, 2, 3, 4, 6, 6, 6, 7]

In [114]:

    

seq = [7, 2, 3, 7, 5, 6, 0, 1]
seq[1:5]


    

    
Out[114]:





[2, 3, 7, 5]

In [116]:

    

seq[3:4] = [6, 3]
seq


    

    
Out[116]:





[7, 2, 3, 6, 3, 3, 5, 6, 0, 1]

In [117]:

    

seq[:5]


    

    
Out[117]:





[7, 2, 3, 6, 3]

In [118]:

    

seq[3:]


    

    
Out[118]:





[6, 3, 3, 5, 6, 0, 1]

In [119]:

    

seq[-4:]


    

    
Out[119]:





[5, 6, 0, 1]

In [120]:

    

seq[-6:-2]


    

    
Out[120]:





[3, 3, 5, 6]

In [121]:

    

seq[::2]


    

    
Out[121]:





[7, 3, 3, 5, 0]

In [122]:

    

seq[::-1]


    

    
Out[122]:





[1, 0, 6, 5, 3, 3, 6, 3, 2, 7]

In [123]:

    

for i, value in enumerate(seq):
    print i, value


    

    




0 7
1 2
2 3
3 6
4 3
5 3
6 5
7 6
8 0
9 1

In [124]:

    

some_list = ['foo', 'bar', 'baz']
mapping = dict((v, i) for i, v in enumerate(some_list))
mapping


    

    
Out[124]:





{'bar': 1, 'baz': 2, 'foo': 0}

In [ ]: