ValueError: x and y must have same first dimension, but have shapes (10, 1) and (90,)

Question

I'm learning ML from Udemy. From one of the lectures of Polynomial Regression, the following code is as follows:

# importing libraries
import pandas as pd
import numpy as np
import matplotlib.pyplot as plt

# importing dataset
dataset = pd.read_csv("Position_Salaries.csv")
x = dataset.iloc[:, 1:2].values
y = dataset.iloc[:, 2].values
print(x.shape)
print(y.shape)
# fitting LR to the dataset
from sklearn.linear_model import LinearRegression
linreg = LinearRegression()
linreg.fit(x, y)

# fitting PR to the dataset
from sklearn.preprocessing import PolynomialFeatures
polreg = PolynomialFeatures(degree=2)
x_poly = polreg.fit_transform(x)
linreg2 = LinearRegression()
linreg2.fit(x_poly, y)


# visualising the polynomial regression results
x_grid = np.arange(min(x), max(x), 0.1)
x_grid = x_grid.reshape((len(x_grid), 1))
plt.scatter(x, y, color = "red")
plt.plot(x, linreg2.predict(polreg.fit_transform(x_grid)), color = "blue" )
plt.title("Truth or Bluff PR")
plt.xlabel("Position")
plt.ylabel("Salary")
plt.show()

I got error as follows:

Traceback (most recent call last):
  File "/home/ashutosh/Machine Learning A-Z Template Folder/Part 2 - Regression/Section 6 - Polynomial Regression/P14-Polynomial-Regression/Polynomial_Regression/plr.py", line 29, in <module>
    plt.plot(x, linreg2.predict(polreg.fit_transform(x_grid)), color = "blue" )
  File "/usr/local/lib/python3.7/dist-packages/matplotlib/pyplot.py", line 2795, in plot
    is not None else {}), **kwargs)
  File "/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_axes.py", line 1666, in plot
    lines = [*self._get_lines(*args, data=data, **kwargs)]
  File "/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_base.py", line 225, in __call__
    yield from self._plot_args(this, kwargs)
  File "/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_base.py", line 391, in _plot_args
    x, y = self._xy_from_xy(x, y)
  File "/usr/local/lib/python3.7/dist-packages/matplotlib/axes/_base.py", line 270, in _xy_from_xy
    "have shapes {} and {}".format(x.shape, y.shape))
ValueError: x and y must have same first dimension, but have shapes (10, 1) and (90,)

the data set can be downloaded from here: https://sds-platform-private.s3-us-east-2.amazonaws.com/uploads/P14-Polynomial-Regression.zip

What can I do?

Answer 1

int the line 29, write x_grid instead of x ie, from

plt.plot(x, linreg2.predict(polreg.fit_transform(x_grid)), color = "blue" )

to

plt.plot(x_grid, linreg2.predict(polreg.fit_transform(x_grid)), color = "blue" )