pandas入门

数组创建：

data = ['a','b','c','d','e']
res= pd.Series(data,index=[i for i in range(1,6)],dtype=str)
print(res)

字典创建

data = {"a":1.,"b":2,"c":3,"d":4}
res = pd.Series(data,index=["d","c","b","a"])
print(res)        # 字典的键用于构建索引

常量创建

# 如果数据是常量值，则必须提供索引。将重复该值以匹配索引的长度。
res = pd.Series(5,index=[1,2,3,4,5])
print(res) 

切片

data = [1,2,3,4,5]
res = pd.Series(data,index=["a","b","c","d","e"])
print(res[0:3],"---")  # 这里跟python的切片一样
print(res[3],"---")
print(res[-3:],"---")

使用索引检索数据

data = [1,2,3,4,5]
res = pd.Series(data,index=["a","b","c","d","e"])
print(res["a"])
# 检索多个值 标签用中括号包裹
print(res[["a","b"]]) # 如果用没有的标签检索则会抛出异常KeyError: 'f'

data = [1,2,3,4,5]
res = pd.Series(data)
res[[2,4]]

使用head()/tail()查看前几个或后几个

data = [1,2,3,4,5]
res = pd.Series(data,index=["a","b","c","d","e"])
res.head(3)  # 查看前三个
res.tail(2)  # 查看后两个