Python实战练习：打怪升级之路

1. 求一个数的幂值

def mi(a, b):
    c = a
    for i in range(b-1):
        a = a * c
    return a


print(mi(2, 4))

2. 输出斐波那契数列

def feibonaqi(n):
    l = []
    a = 1
    b = 1
    for i in range(n):
        l.append(a)
        l.append(b)
        a = b + a
        b = a + b
    print(l)


feibonaqi(5)

3. 输出特定字典数据

keys = ['name', 'old', 'score']
values = [
    ['yee', 3, 99], ['rose', 18, 8], ['green', 30, 90]
]
要输出结果：
[{'name': 'yee', 'old': 3, 'score': 99}, {'name': 'rose', 'old': 18, 'score': 8}, {'name': 'green', 'old': 30, 'score': 90}]

正确示范：

keys = ['name', 'old', 'score']
values = [
    ['yee', 3, 99], ['rose', 18, 8], ['green', 30, 90]
]
l = []
for value in values:
    d = {}
    for i in range(len(keys)):
        d[keys[i]] = value[i]
    l.append(d)
print(l)

错误示范：

keys = ['name', 'old', 'score']
values = [
 ['yee', 3, 99], ['rose', 18, 8], ['green', 30, 90]
]
l = []
d = {}
for value in values:
 for i in range(len(keys)):
     d[keys[i]] = value[i]
 l.append(d)
print(l)

错误原因：

列表追加的元素指向的是同一个字典d，若d字典的键值变化也会同步到列表

例如：

cc = []
aa = {'name': 'green', 'old': 30, 'score': 90}
cc.append(aa)
aa['name'] = 'yee'
aa['old'] = 3
aa['score']= 99
cc.append(aa)
print(cc)

输出结果是：[{‘name’: ‘yee’, ‘old’: 3, ‘score’: 99}, {‘name’: ‘yee’, ‘old’: 3, ‘score’: 99}]

4. 分批次读取文件内容，每次读取100行

def read_file():
    with open('id.txt', 'r') as file:
        print(type(file))
        for i, j in enumerate(file, 1):
            print(i, j)
            if i % 100 == 0:
                yield


content = read_file()

while True:
    print('--------------------------------------------')
    try:
        content.__next__()
    except StopIteration:
        break

改良版：

def read_file():
    with open('id.txt', 'r') as file:
        mark = []
        for i, j in enumerate(file, 1):
            mark.append(j.strip('\n'))
            if i % 100 == 0:
                yield mark
                mark = []
        if mark == []:
            yield mark


content = read_file()
for i in content:
    print(i)
    print('----------')

作者：caroltr