python基础知识入门_python新手学院

>>> str = "I'm David"
>>> str1 = 'I told my friend,"i love Python"'

>>> name = "hello python world"
>>> print(name.title())
Hello Python World

>>> str1 = "I love python"
>>> print(str1.upper())  #将字符串改为全部大写
I LOVE PYTHON
>>> print(str1.lower())   #将字符串改为全部小写
i love python

>>> first_name = "Guido"
>>> last_name = "van Rossum"
>>> full_name = first_name + " " + last_name
>>> print(full_name)
Guido van Rossum

>>> print("Languages:\n\tPython\n\tC++\n\tPHP")
Languages:
    Python
    C++
    PHP

>>> name = " p y t h o n "
>>> print(name.rstrip()) #删除字符串右端空格
 p y t h o n
>>> print(name.lstrip())  #删除字符串左端空格
p y t h o n 
>>> print(name.strip())   #删除字符串两端空格
p y t h o n
>>> print(name.replace(' ',''))  #删除字符串全部空格包括制表符和换行符
python

>>> name = "Hello World"
>>> print(name[0])
H
>>> print(name[0:-1])
Hello Worl
>>> print(name[-1])
d
>>> print(name[::])
Hello World
>>> print(name[0:11])
Hello World

>>> name = "hello world"
>>> print(name.find('d'))
10

>>> name = "hello world"
>>> print(name.count('l'))
3

>>> name = "hello world"
>>> print(name.split(' '))
['hello', 'world']
>>> print(name.split(' ',0))
['hello world']

>>> "{}:计算机{}的CPU占用率为{}%".format('2019-03-25','python',10)  #S.format(*args, **kwargs) -> string
'2019-03-25:计算机python的CPU占用率为10%'
>>> "%s:计算机%s的CPU占用率为%d%%" % ('2019-03-25','python',10)   #%用法
'2019-03-25:计算机python的CPU占用率为10%

>>> A = {"python",'666',("wenwei-blog",666)}
{'python', '666', ('wenwei-blog', 666)}
>>> B = set("pypy")
{'y', 'p'}
>>> C = {"python",123,"python",123}
{'python', 123}

>>> digits = [1,23,434,55,44,67]
>>> min(digits)
1
>>> max(digits)
434
>>> sum(digits)
624

>>> digits = [value for value in range(1,101)];sum(digits)
5050

>>> for i in range(1,21,2):
    print(i)
    
1
3
5
7
9
11
13
15
17
19

>>> lists = [n for n in range(3,31)]
>>> lists
[3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]
>>> for i in lists:
    if i % 3 == 0:
        print(i)

        
3
6
9
12
15
18
21
24
27
30

>>> names = ('zhiwenwei','zhouyouxian')
>>> names.index('zhiwenwei')
0
>>> names.count('zhiwenwei')
1

>>> city = {'中国':'北京','美国':'纽约','法国':'巴黎'}
>>> city
{'中国': '北京', '美国': '纽约', '法国': '巴黎'}

pip install jieba

>>> word1 = jieba.lcut("python无所不能！除了生不出孩子,我们应该学习使用它！")
Building prefix dict from the default dictionary ...
Dumping model to file cache /tmp/jieba.cache
Loading model cost 1.832 seconds.
Prefix dict has been built succesfully.
>>> print(word1,type(word1))
['python', '无所不能', '！', '除了', '生不出', '孩子', ',', '我们', '应该', '学习', '使用', '它', '！'] <class 'list'>

#Hamlet词频统计
def getText():
    txt = open("hamlet",'r').read()
    txt = txt.lower() #大写字母转换小写
    for word in '~!@#$%^&*()_+-={}[],./:";<>?':
        txt = txt.replace(word," ")#把多余符号转换为空格
    return txt
hamletTxt = getText()
words = hamletTxt.split() #以空格拆分为列表
counts = {}
for word in words:
    counts[word] = counts.get(word,0) + 1 #以每个词为键，值默认0，,每出现一次累加1
items = list(counts.items())
items.sort(key=lambda x:x[1],reverse=True) #[1]按照第二维排序，reverse=True表示降序
for i in range(10):
    word,count = items[i]
    print("{0:<10}{1:5}".format(word,count))

import jieba
txt = open("Threekingdoms", 'r', encoding="utf-8").read()
excludes = {'将军','却说','荆州','二人','不可','不能','如此'}
words = jieba.lcut(txt)
counts = {}
for word in words:
    if len(word) == 1:
        continue
    #书中同一人物多个名字统一改为一个名字
    elif word == '诸葛亮' or word == '空明日':
        rword = "孔明"
    elif word == '关公' or word == '云长':
        rword = "关羽"
    elif word == '玄德' or word == '玄德日':
        rword = "刘备"
    elif word == '孟德' or word == '丞相':
        rword = "曹操"
    else:
        rword = word
    counts[word] = counts.get(word, 0) + 1
for word in excludes:
    del counts[word]  #去重
items = list(counts.items())
items.sort(key=lambda x:x[1],reverse=True)
for i in range(10):
    word,count = items[i]
    print("{0:<10}{1:>5}".format(word,count))

guess = eval(input("请输入数字："))
if guess == 88:
    print("猜对了")

guess = eval(input("请输入数字："))
if guess == 88:
    print("猜对了")
else:
    print("猜错了")

age = 25
count = 0
while count < 3:
    guess_age = int(input("guess_age:"))
    if guess_age == age:
        print("yes,you got it!!!")
        break
    elif guess_age > age:
        print("think smaller...")
    else:
        print("think bigger...")
    count += 1

try:
    num = eval(input("请输入数字"))
    print(num**2)
except:
    print("你输入的不是数字")

height,weight = eval(input("请输入身体(米)和体重(公斤)[逗号分开]："))
bmi = weight / pow(height,2)
print("BMI数值为：{:.2f}".format(bmi))#.2f#保留两位小数
who,nat = "",""
if bmi < 18.5:
    who,nat = "偏瘦","偏瘦"
elif 18.5 <= bmi < 24:
    who,nat = "正常","正常"
elif 24 <= bmi < 25:
    who,nat = "正常","偏胖"
elif 25 <= bmi < 28:
    who,nat = "偏胖","偏胖"
elif 28 <= bmi <30:
    who,nat = "偏胖","肥胖"
else:
    who,nat = "肥胖","肥胖"
print("BMI指标为：国际'{}',国内'{}'".format(who,nat))

def test(n,m=1): #m为可选参数
    s = 1
    for i in range(1,n+1):
        s *= i
    print(s//m)
test(10)
test(10,2)

def test(n,*args):#args为可变参数，也可以命名其他值
    s = 1
    for i in range(1,n+1):
        s += i
    for item in args:
        s += item
    print(s)
test(10,3)
test(10,3,1,5)

def test(*args,**kwargs):
    print("args =",args)
    print("kwargs =",kwargs)
    print("----------------------------------")
if __name__ == '__main__':
    test(1,5,94,564)
    test(a=1,b=2,c=3)
    test(1,2,3,4,a=1,b=2,c=3)
    test('I love python',1,None,a=1,b=2,c=3)

g = lambda x,y:x*y
print(g(4,5))

pip install wordcloud

import wordcloud
w = wordcloud.WordCloud()  #设置wordcloud对象
w.generate("Python by WordCloud,is fun and powerful!") #配置对象参数并加载词云文本
w.to_file("outfile.png") #输出词云文件

import wordcloud
w = wordcloud.WordCloud()
text = "life is short, you need python"
w = wordcloud.WordCloud(background_color="white",width=500,height=300,
                        min_font_size=20,max_font_size=40,font_step=6,
                        max_words=5)
w.generate(text)
w.to_file("outfile2.png")

import wordcloud
import jieba
text = """
wordcloud是python非常优秀的第三方库，词云以词语为基本单位更加直观和艺术的展示文本词云图，\
也叫文字云，是对文本中出现频率较高的关键词予以视觉化的展现，词云图过滤掉大量的低频低质的文本信息，\
使得浏览者只要一眼扫过文本就可领略文本的主旨。基于Python的词云生成类库,好用功能强大。\
在做统计分析的时候有着很好的应用。
"""
w = wordcloud.WordCloud(width=800,height=400,font_path="msyh.ttc")
w.generate(" ".join(jieba.lcut(text))) #中文需要先分词并组成空格分隔字符串
w.to_file("outfile3.png")

import wordcloud
import jieba
f = open("新时代中国特色社会主义","r",encoding="utf-8")
text = jieba.lcut(f.read())
text = " ".join(text)
f.close()
w = wordcloud.WordCloud(background_color='white',width=800,height=400,font_path="msyh.ttc")
w.generate(text)
w.to_file("outfile4.png")

import wordcloud
import jieba
from scipy.misc import imread
#图片必须是白色背景色
mask = imread('five-pointed star.png')
f = open("新时代中国特色社会主义","r",encoding="utf-8")
text = jieba.lcut(f.read())
text = " ".join(text)
f.close()
w = wordcloud.WordCloud(background_color='white',width=1000,height=700,font_path="msyh.ttc",mask=mask)
w.generate(text)
w.to_file("outfile5.png")