[英]Cant make Prediction on OLS Model
我正在構建一個 OLS Model 但無法做出任何預測。
你能解釋一下我做錯了什么嗎?
建設model:
import numpy as np
import pandas as pd
from scipy import stats
import statsmodels.api as sm
import matplotlib.pyplot as plt
d = {'City': ['Tokyo','Tokyo','Lisbon','Tokyo','Madrid','New York','Madrid','London','Tokyo','London','Tokyo'],
'Card': ['Visa','Visa','Visa','Master Card','Bitcoin','Master Card','Bitcoin','Visa','Master Card','Visa','Bitcoin'],
'Colateral':['Yes','Yes','No','No','Yes','No','No','Yes','Yes','No','Yes'],
'Client Number':[1,2,3,4,5,6,7,8,9,10,11],
'Total':[100,100,200,300,10,20,40,50,60,100,500]}
d = pd.DataFrame(data=d).set_index('Client Number')
df = pd.get_dummies(d,prefix='', prefix_sep='')
X = df[['Lisbon','London','Madrid','New York','Tokyo','Bitcoin','Master Card','Visa','No','Yes']]
Y = df['Total']
X1 = sm.add_constant(X)
reg = sm.OLS(Y, X1).fit()
reg.summary()
預言:
d1 = {'City': ['Tokyo','Tokyo','Lisbon'],
'Card': ['Visa','Visa','Visa'],
'Colateral':['Yes','Yes','No'],
'Client Number':[11,12,13],
'Total':[0,0,0]}
df1 = pd.DataFrame(data=d1).set_index('Client Number')
df1 = pd.get_dummies(df1,prefix='', prefix_sep='')
y_new = df1[['Lisbon','Tokyo','Visa','No','Yes']]
x_new = df1['Total']
mod = sm.OLS(y_new, x_new)
mod.predict(reg.params)
然后顯示: ValueError: shapes (3,1) and (11,) not aligned: 1 (dim 1) != 11 (dim 0)
我究竟做錯了什么?
這是代碼的固定預測部分和我的評論:
d1 = {'City': ['Tokyo','Tokyo','Lisbon'],
'Card': ['Visa','Visa','Visa'],
'Colateral':['Yes','Yes','No'],
'Client Number':[11,12,13],
'Total':[0,0,0]}
df1 = pd.DataFrame(data=d1).set_index('Client Number')
df1 = pd.get_dummies(df1,prefix='', prefix_sep='')
x_new = df1.drop(columns='Total')
主要問題是訓練X1
和x_new
數據集的假人數量不同。 下面我添加了缺失的虛擬列並用零填充:
x_new = x_new.reindex(columns = X1.columns, fill_value=0)
現在x_new
有適當的列數等於訓練數據集X1
:
const Lisbon London Madrid ... Master Card Visa No Yes
Client Number ...
11 0 0 0 0 ... 0 1 0 1
12 0 0 0 0 ... 0 1 0 1
13 0 1 0 0 ... 0 1 1 0
[3 rows x 11 columns]
最后使用先前訓練的 model reg
對新數據集x_new
進行預測:
reg.predict(x_new)
結果:
Client Number
11 35.956284
12 35.956284
13 135.956284
dtype: float64
附錄
根據要求,我在下面附上完全可重現的代碼來測試訓練和預測任務:
import numpy as np
import pandas as pd
from scipy import stats
import statsmodels.api as sm
import matplotlib.pyplot as plt
d = {'City': ['Tokyo','Tokyo','Lisbon','Tokyo','Madrid','New York','Madrid','London','Tokyo','London','Tokyo'],
'Card': ['Visa','Visa','Visa','Master Card','Bitcoin','Master Card','Bitcoin','Visa','Master Card','Visa','Bitcoin'],
'Colateral':['Yes','Yes','No','No','Yes','No','No','Yes','Yes','No','Yes'],
'Client Number':[1,2,3,4,5,6,7,8,9,10,11],
'Total':[100,100,200,300,10,20,40,50,60,100,500]}
d = pd.DataFrame(data=d).set_index('Client Number')
df = pd.get_dummies(d,prefix='', prefix_sep='')
X = df[['Lisbon','London','Madrid','New York','Tokyo','Bitcoin','Master Card','Visa','No','Yes']]
Y = df['Total']
X1 = sm.add_constant(X)
reg = sm.OLS(Y, X1).fit()
reg.summary()
###
d1 = {'City': ['Tokyo','Tokyo','Lisbon'],
'Card': ['Visa','Visa','Visa'],
'Colateral':['Yes','Yes','No'],
'Client Number':[11,12,13],
'Total':[0,0,0]}
df1 = pd.DataFrame(data=d1).set_index('Client Number')
df1 = pd.get_dummies(df1,prefix='', prefix_sep='')
x_new = df1.drop(columns='Total')
x_new = x_new.reindex(columns = X1.columns, fill_value=0)
reg.predict(x_new)
最大的問題是您沒有使用相同的虛擬轉換。 也就是說,df1 中的某些值不存在。 您可以使用以下代碼(來自此處)添加缺失值/列:
d1 = {'City': ['Tokyo','Tokyo','Lisbon'],
'Card': ['Visa','Visa','Visa'],
'Colateral':['Yes','Yes','No'],
'Client Number':[11,12,13],
'Total':[0,0,0]}
df1 = pd.DataFrame(data=d1).set_index('Client Number')
df1 = pd.get_dummies(df1,prefix='', prefix_sep='')
print(df1.shape) # Shape is 3x6 but it has to be 3x11
# Get missing columns in the training test
missing_cols = set( df.columns ) - set( df1.columns )
# Add a missing column in test set with default value equal to 0
for c in missing_cols:
df1[c] = 0
# Ensure the order of column in the test set is in the same order than in train set
df1 = df1[df.columns]
print(df1.shape) # Shape is 3x11
此外,您混淆了x_new
和y_new
。 所以應該是:
x_new = df1.drop(['Total'], axis=1).values
y_new = df1['Total'].values
mod = sm.OLS(y_new, x_new)
mod.predict(reg.params)
請注意,我使用x_new = df1.drop(['Total'], axis=1).values
而不是df1[['Lisbon','Tokyo','Visa','No','Yes']]
更方便(就 1)而言更不容易(打字)錯誤和 2)代碼更少
首先,您需要對所有單詞進行字符串索引,或者對值進行單熱編碼。 ML 模型不接受文字,只接受數字。 接下來,您希望 X 和 y 為:
X = d.iloc[:,:-1]
y = d.iloc[:,-1]
這樣,X 的形狀為 [11,3],而 y 的形狀為 [11,],這是所需的正確形狀。
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