列表字典实例

矩阵转换

#!/usr/local/bin/python3

# 通用
def transpose_irregular(matrix_s):
    print('原矩阵为:',matrix_s)
    matrix_d = [[0 for col in range(len(matrix_s))] for row in range(len(matrix_s[0]))]
    print(matrix_d)
    for i in range(len(matrix_s[0])):
        for j in range(len(matrix_s)):
            matrix_d[i][j] = matrix_s[j][i]
    return matrix_d

# 方阵
def transpose_regular(matrix_s):
    print('原矩阵为:',matrix_s)
    for i in range(len(matrix_s)):
        for j in range(i):
            matrix_s[i][j],matrix_s[j][i]=matrix_s[j][i],matrix_s[i][j]

    return matrix_s

if __name__ ==  '__main__':
    row=int(input('输入矩阵行数：'))
    col=int(input('输入矩阵列数：'))
    matrix_s=[[0 for col in range(col)] for row in range(row)]
    for i in range(row):
        matrix_s[i] = input('输入第%s行数据:'%i).split(' ')

    if len(matrix_s) == len(matrix_s[0]):
        matrix_d=transpose_regular(matrix_s)
    else:
        matrix_d=transpose_irregular(matrix_s)
    print('转换后矩阵为:',matrix_d)

统计词频

# 方法一
content = ""
words = content.split()                                         
# 数据清洗
for i in  range(len(words)):    
    words[i] = words[i].strip('.,;')      # 去掉标点
    words[i] = words[i].lower()       # 大些转小写
 
# 统计
for word in words:
    hist[word] = hist.get(word,0) + 1

# 排序
data = list(hist.items())
data.sort(key=lambda x:x[1],reverse=True)


# 方法二
import os
from collections import Counter
content = ''
data_t = Counter(re.split('W+',data))
data_t = data_t.most_common(10)                    # 统计频率最高的10个词

列表/字典解析 元组

from random import randint

data = [randint(-10,10) for x in range(10)]
print(data)

# fileter 函数
data_f = filter(lambda x: x >= 0, data)
print([data for data in data_f])

# 列表解析
data_l = [x for x in data if x >=0]
print(data_l)



# 字典解析
d = {x: randint(60,100) for x in range(1,21)}
print(d)

d_s = {k:v for k, v in d.items() if v > 90}
print(d_s)

元组namedtuple的使用

from collections import namedtuple

Student = namedtuple('Student',['name','age','gender','email'])
s = Student('ray',18,'male','raygift@163.com')
print(s.name,s.age,s.gender,s.email)

根据字典中值的大小,对字段中项排序

from random import randint
d = {x:randint(60, 100) for x in 'xyzabc'}
print(d)

# zip 实现
temp = zip(d.values(), d.keys())
print(list(temp))

# sorted实现
temp = sorted(d.items(),key=lambda x: x[1])
print(temp)

找多个字典中的公共键(key)

from random import randint, sample

d1 = {x:randint(1,4) for x in sample('abcdefg', randint(3,6))}
d2 = {x:randint(1,4) for x in sample('abcdefg', randint(3,6))}
d3 = {x:randint(1,4) for x in sample('abcdefg', randint(3,6))}

print(d1,d2,d3)
print(d1.keys() & d2.keys() & d3.keys())


from functools import reduce
print(reduce(lambda a,b:a &b, map(dict.keys,[d1,d2,d3])))

让字典有序

from collections import OrderedDict
from time import time
from random import randint

d = OrderedDict()
players = list('abcdefgh')
start = time()


for i in range(8):
    input()
    p = players.pop(randint(0,7 -i))
    end = time()
    print(i+1,p,end-start)
    d[p] = (i+1,end-start)

print("-"*30)

for k in d:
    print(k,d[k])

历史记录

from collections import deque
from random import randint

N = randint(0,100)
history = deque([],5)

def guess(k):

    if k == N:
        print('right')
        return  True
    if k < N:
        print('%s is less than N'%k)
    else:
        print('%s is great than N'%k)


while True:
    line = input('please input a number:')

    if line.isdigit():
        k = int(line)
        history.append(k)
        if guess(k):
            break

    elif line == 'history' or line == 'h?':
        print(list(history))


import pickle
q = [x for x in range(10)]

pickle.dump(q,open('history','wb+'))
print(pickle.load(open('history','rb+')))