Expected 2D array, got 1D array instead: for a simple linear regression model in Python- Jupyter Notebook

723 Asked by ranjan_6399 in Python , Asked on Jun 10, 2021

I am trying to learn data science with python by browsing on the net and going through random topics and websites.

After a long time of learning, I tried to get hands-on experience, so I started coding the linear regression model and after coding, I am getting stuck with an error.

I am mentioning the code which I used to build the linear regression model and also the error below. Can anyone help me out with solving the error?

import pandas as pd
import numpy as np
import matplotlib.pyplot as plt
from numpy.random import randn
np.random.seed(101)
df3=pd.DataFrame(randn(5,2),index ='0 1 2 3 4'.split(), columns='Test Price'.split())
y= df3['Price']
x= df3['Test']
import sklearn.model_selection as model_selection
X_train, X_test, y_train, y_test = model_selection.train_test_split(x, y, test_size=0.2, random_state=101)
from sklearn.linear_model import LinearRegression
lm2= LinearRegression()
lm2.fit(X_train,y_train)
ERROR
ValueError: Expected 2D array, got 1D array instead:
array=[-2.01816824  0.65111795  0.90796945 -0.84807698].
Reshape your data either using array.reshape(-1, 1) if your data has a single feature or array.reshape(1, -1) if it contains a single sample.

Answered by Ranjana Admin

As shown the error mentions that you are passing a single dimension array but you need to pass the two-dimensional array. So you need to reshape the array using the reshape () function

You need to reshape X using the code as shown below:

lm2.fit(X_train.values.reshape(-1,1),y_train)

Here you are reshaping the X to (n_samples,1). in your case -1 represents the n_sample.

 This will remove “valueerror: expected 2d array, got 1d array instead”

Expected 2D array, got 1D array instead: for a simple linear regression model in Python- Jupyter Notebook

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