Day7:Filesprocess,Iterator and Generator

# r r+ w w+ a(add in the eend b+
"""

# f = open('陈粒','r',encoding='utf-8')
data = f.read()
print(f.readable())
print(f.writable())
print(f.readline())
# just read one line each time
print(f.readlines())
# read all the lines and put in a list
print(data)

f = open('陈粒1','r+',encoding='utf-8')
f.write('I have seen the desert raining
')
data = f.read()
print(data)
f.close()

"""

with open('chenli','r',encoding='utf-8') as sdr_s,with open('chenli1','w',encoding='utf-8') as dtr_s:
data = sdr_s.read()
dtr_s.write(data)
f = open('dtr_s','r',encoding='utf-8')
data = f.read()
print(data)

#iterator and generator:satisfy the principle(__iter__(),means have the use of __next__()

# 1:
l = [1,2,3,4] 
iter_1 = l.__iter__()
print(iter_1.__next__())
print(iter_1.__next__())
print(iter_1.__next__())
print(next(iter_1))
# next():the inner function of python;the same as iter_1.__next__()
# 2:
for i in l:
#iter_1 = l.__iter__() print(iter_1.__next__())
print(i)
# 3:
print(l[2])
# 4:index
index = 0
while index < len(l):
print(l[index])
index += 1
# as for dict(return the key values) and files can also use the 'for' sentence

# ***************generator is iterator :
# 1:generator function(replace the return to yield and yield can retain the function's state)

def test():
print('start born:')
print('start born:')
print('start born:')
yield 'me'
print('born son')
yield 'son'
print('born grandson')
yield 'grandson'
g = test()
print(g)
print(g.__next__())
print(g.__next__())
print(g.__next__())

# 2: ternary expression:

# name = 'alex'
name = 'zxver'
res = 'SB' if name == 'alex' else 'beauty'
print(res)

l = ['egg%s' %i for i in range (10)]
l1 = ['egg%s' %i for i in range (10) if i < 5]
print(l)
print(l1) 
# use tuple
l2 = ('egg%s' %i for i in range (10))
print(l2)
print(l2.__next__())
print(l2.__next__())
print(l2.__next__())
print(l2.__next__())
print(next(l2))

# generator can save the memory: use tuple
print(sum(i for i in range(10000000)))

def produce_baozi():
for i in range(100):
# return i
yield 'sale a baozi%s' %i

pro_g = produce_baozi()
baozi1 = pro_g.__next__()
print(baozi1)
baozi2 = pro_g.__next__()
print(baozi2)
baozi3 = pro_g.__next__()
print(baozi3)
# yield can return mutiple numbers and can use the return value directly

def census():
with open('pop.py') as f:
for line in f:
p = eval(line)
yield p['population']
c = census()
#print(c.__next__())
#print(c.__next__())
#print(c.__next__())
#print(c.__next__())
all_pop = sum(i for i in c)
print(all_pop)
###################calculate the rate:(no any return value cause the generator can just overall on time)
for q in c:
print(q/all_pop)

# send(self,value),can send the value to the last yield

def sen():
print('start')
# yield 1
# firt = yield 1
firt = yield
print('the next',firt)
yield 2
s = sen()
print(s.__next__())
# print(s.__next__())
# print(s.send(None))
print(s.send('value'))

# eat baozi:two separate section

import time
def consumer(name):
print('I %s start to eat baozi' %name)
while True:
baozi = yield
time.sleep(1)
print('%s is eat %s' %(name,baozi))
def producer():
c1 = consumer('zxver')
c2 = consumer('alex')
c1.__next__()
c2.__next__()
# c1.send('baozi')
for i in range(10):
time.sleep(1)
c1.send('baozi %s' %i)
c2.send('baozi %s' %i)
producer()