数据处理15-1

import numpy as np
import pandas as pd # 通常会将pandas命名为pd

mydataset = {
    "sites":["google",'baidu',"bilibili"],
    "numbers":[1,2,3]
} # 这是字典，键值成对出现

myvar = pd.DataFrame(mydataset)
print(myvar)


# None (python) Null(数据库)
# pandas 的空值用NaN表示，not a number

numlist = [1,2,3]
myvar = pd.Series(numlist,index=['a','b','c'],name='numlist')
print(myvar)

print("索引是b的位置上的值：",myvar['b'])

# 将字典转换成Series
mydict = {'no1':'zhangchengdong','no2':'zhangsan','no3':'lisi'}
mySeries = pd.Series(mydict)
print(mySeries['no1'])
# 字典的key变成索引，value变成data

mySeries = pd.Series(mydict,index=['no1','no3'])
print(mySeries)

mySeries = pd.Series(np.array([1,2,3,4]))
# 把[1,2,3,4]转换成numpy的数组，在转换成Series
print(mySeries)

print(mySeries[1:3])

mySeries = pd.Series({'a':1,'b':2,'c':3,'d':4})

print(mySeries)
print(mySeries['a':'c'])

mySeries = pd.Series({1:1,2:2,3:3,4:4})

print(mySeries)
print(mySeries[1:3])