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习惯导入方法
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
3.1 Series数据结构
3.1.1 Series是什么
一维数组
3.1.2 创建一个Series
import pandas as pd
# 出入一个列表
pd.Series([1,2,3])
# 指定索引
pd.Series([1,2,3],index=["a","b","c"])
# 传入一个字典
pd.Series({1:"a",2:"b",3:"c"})
out:
0 1
1 2
2 3
dtype: int64
3.1.3 利用index方法获取Series的索引
S1=pd.Series([1,2,3],index=["a","b","c"])
S1.index
out:
Index(['a', 'b', 'c'], dtype='object')
3.1.4 利用values方法获取Series的值
S1.values
out:
array([1, 2, 3], dtype=int64)
3.2 DataFrame 表格型数据结构
3.2.1 DataFrame是什么
一组数据和行索引、列索引组成的表格型数据结构
3.2.2 创建一个DataFrame
import pandas as pd
# 传入一个列表
df1 = pd.DataFrame(["a","b","c","d"])
print(df1)
# 传入一个嵌套列表,2列。通过zip()可以创建
df2 = pd.DataFrame([["a","A"],["b","B"],["c","C"],["d","D"]])
print(df2)
# 指定行、列索引
df3 = pd.DataFrame([["a","A"],["b","B"],["c","C"],["d","D"]],columns = ["小写","大写"],index=["一","二","三","四"])
print(df3)
# 传入一个字典
df4 = pd.DataFrame({"小写":["a","b","c","d"],"大写":["A","B","C","D"]})
print(df4)
输出
小写 大写
一 a A
二 b B
三 c C
四 d D
3.2.3 获取DataFrame的行、列索引
df3.columns
df3.index
输出
Index(['小写', '大写'], dtype='object')
Index(['一', '二', '三', '四'], dtype='object')