cannot import name 'Imputer' from 'sklearn.preprocessing'

The 'Imputer' class has been deprecated since version 0.22 and removed in version 0.24 of scikit-learn. You should use 'SimpleImputer' instead. Here's an example of how to use 'SimpleImputer':

from sklearn.impute import SimpleImputer

# create an instance of the imputer class
imputer = SimpleImputer(strategy='mean')

# fit the imputer to the data
imputer.fit(X)

# transform the data
X_imputed = imputer.transform(X)

In this example, 'X' is the input data that contains missing values. 'strategy' parameter in SimpleImputer is used to specify how to impute the missing values. Here, we are using the mean of the columns to impute missing values. You can change the strategy to 'median' or 'most_frequent' depending on your requirements.