xdc_git_python_20210511/乱七八糟/pandas_numpy.py

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt

array = np.array([[1,2,3],
                    [3,4,5]])
print(array)
print('几唯：',array.ndim)
print('几行几列:',array.shape)
print('大小：', array.size)


a = np.array([10,20,30,40])
b = np.arange(4)
print(a,b)
# 减法
c = a-b
print(c)

# pandas 合并concat

df1 = pd.DataFrame(np.ones((3,4))*0,columns=['a','b','c','d'])
df2 = pd.DataFrame(np.ones((3,4))*1,columns=['a','b','c','d'])
df3 = pd.DataFrame(np.ones((3,4))*2,columns=['a','b','c','d'])

# print(df1)
# print(df2)
# print(df3)

res = pd.concat([df1,df2,df3],axis=0,ignore_index=True)
print(res)


# join, 

df1 = pd.DataFrame(np.ones((3,4))*0,columns=['a','b','c','d'],index=[1,2,3])
df2 = pd.DataFrame(np.ones((3,4))*1,columns=['b','c','d','e'],index=[2,3,4])

print(df1)
print(df2)

res = pd.concat([df1,df2],join='inner',ignore_index=True)
print(res)

# 新版本已经丢弃，
# res = pd.concat([df1,df2],axis=1,join_axes=[df1.index])  
print(df1.append(df2,ignore_index=True))

data = pd.Series(np.random.randn(1000),index=np.arange(1000))
data = data.cumsum()
# data.plot()
# plt.show()

#DataFrame
data = pd.DataFrame(np.random.randn(1000,4),
            index=np.arange(1000),
            columns=list("ABCD"))

data.cumsum()

ax = data.plot.scatter(x='A',y='B',color='DarkBlue',label='Class 1')
data.plot.scatter(x='A',y='C',color='DarkGreen',label='Class 2',ax=ax)
# data.plot()
plt.show()