[英]My train/test model is returning an error and is train/test model and normal linear regression model two separate models?
I recently attending a class where the instructor was teaching us how to create a linear regression model using Python.我最近参加了一个 class,讲师正在教我们如何使用 Python 创建线性回归 model。 Here is my linear regression model:这是我的线性回归 model:
import matplotlib.pyplot as plt
import pandas as pd
from scipy import stats
import numpy as np
from sklearn.metrics import r2_score
#Define the path for the file
path=r"C:\Users\H\Desktop\Files\Data.xlsx"
#Read the file into a dataframe ensuring to group by weeks
df=pd.read_excel(path, sheet_name = 0)
df=df.groupby(['Week']).sum()
df = df.reset_index()
#Define x and y
x=df['Week']
y=df['Payment Amount Total']
#Draw the scatter plot
plt.scatter(x, y)
plt.show()
#Now we draw the line of linear regression
#First we want to look for these values
slope, intercept, r, p, std_err = stats.linregress(x, y)
#We then create a function
def myfunc(x):
#Below is y = mx + c
return slope * x + intercept
#Run each value of the x array through the function. This will result in a new array with new values for the y-axis:
mymodel = list(map(myfunc, x))
#We plot the scatter plot and line
plt.scatter(x, y)
plt.plot(x, mymodel)
plt.show()
#We print the value of r
print(r)
#We predict what the cost will be in week 23
print(myfunc(23))
The instructor said we now must use the train/test model to determine how accurate the model above is.教练说我们现在必须使用训练/测试 model 来确定上面的 model 有多准确。 This confused me a little as I understood it to mean we will further refine the model above.这让我有点困惑,因为我理解这意味着我们将进一步完善上面的 model。 Or, does it simply mean we will use:或者,它是否仅仅意味着我们将使用:
and compare the r values the two different models yield as well as the predicted values they yield?.并比较两个不同模型产生的 r 值以及它们产生的预测值? Is the train/test model considered a regression model?训练/测试 model 是否被视为回归 model?
I tried to create the train/test model but I'm not sure if it's correct (the packages were imported from the above example).我尝试创建训练/测试 model 但我不确定它是否正确(包是从上面的示例中导入的)。 When I run the train/test code I get the following error:当我运行训练/测试代码时,出现以下错误:
ValueError: Found array with 0 sample(s) (shape=(0,)) while a minimum of 1 is required.
Here is the full code:这是完整的代码:
train_x = x[:80]
train_y = y[:80]
test_x = x[80:]
test_y = y[80:]
#I display the training set:
plt.scatter(train_x, train_y)
plt.show()
#I display the testing set:
plt.scatter(test_x, test_y)
plt.show()
mymodel = np.poly1d(np.polyfit(train_x, train_y, 4))
myline = np.linspace(0, 6, 100)
plt.scatter(train_x, train_y)
plt.plot(myline, mymodel(myline))
plt.show()
#Let's look at how well my training data fit in a polynomial regression?
mymodel = np.poly1d(np.polyfit(train_x, train_y, 4))
r2 = r2_score(train_y, mymodel(train_x))
print(r2)
#Now we want to test the model with the testing data as well
mymodel = np.poly1d(np.polyfit(train_x, train_y, 4))
r2 = r2_score(test_y, mymodel(test_x))
print(r2)
#Now we can use this model to predict new values:
#We predict what the total amount would be on the 23rd week:
print(mymodel(23))
You better split to train and test using sklearn
method:您最好使用sklearn
方法进行训练和测试:
from sklearn.model_selection import train_test_split
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2)
Where X
is your features dataframe and y
is the column of your labels.其中X
是您的特征 dataframe 和y
是您的标签列。 0.2 stands for 80% train and 20% test. 0.2 代表 80% 训练和 20% 测试。
BTW - the error you are describing could be because you dataframe has only 80 rows, leaving x[80:]
empty顺便说一句-您描述的错误可能是因为您 dataframe 只有 80 行,使x[80:]
为空
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