Updates for 2024

[mrdbourke]

Working on updates for 2024

Main goals:

• Make sure all of the code and APIs work with the 2023/2024 version of the various libraries used throughout the course.
• For major changes, I will create new videos/a new document with the changes.

See the branch (work in progress) - https://github.com/mrdbourke/zero-to-mastery-ml/tree/updates-2023 (this branch will get merged into master once the changes are finished)

TODO

• Update README with course outline
• Update README on course book, see: https://dev.mrdbourke.com/zero-to-mastery-ml/
• Structured data projects (section 3)

Working on

• TensorFlow notebook - make this smoother to run in Google Colab, e.g. download data from TensorFlow datasets? Not from Kaggle?
  • See differences between Keras 3.0 and tf.keras here: https://github.com/keras-team/keras-core/issues/223
  • TensorFlow Hub is moving to Kaggle Models, see here for more: https://tfhub.dev/announcement

Done

• NumPy notebook (no major changes)
• Pandas notebook (see changes below)
• Matplotlib notebook (see changes below)
  • seems to be only a video notebook for matplotlib, I'll recreate the original notebook with a bit more information
• Scikit-Learn notebook (slight API changes, see changes below)
• Turn course materials into an online book, see: https://dev.mrdbourke.com/zero-to-mastery-ml/

[mrdbourke]

Pandas notebook updates

Specifying numeric data types

• numeric_only=False now default when calling .mean() on a DataFrame, specify numeric_only=True when calling .mean(), e.g. car_prices.mean(numeric_only=True), see: https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.mean.html
• same goes for .sum() on a DataFrame, numeric_only=False defaults to False, see: https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.sum.html
  • In light of the above, added numeric_only=True to most sections which call .mean() or .sum() on a DataFrame.

String replacement

• To replace a str in pandas, you now must specify whether to use regex or not, the default is False for example:

# Remove price column symbols
car_sales["Price"] = car_sales["Price"].str.replace('[\$\,\.]', '', 
                                                    regex=True) # Tell pandas to replace using regex

• See the documentation for more: https://pandas.pydata.org/docs/reference/api/pandas.Series.str.replace.html

[mrdbourke]

A comment from Mophers, is this taken care of?

[tmcm31416]

Hey all - just starting out on the AI/ML course and was also banging my head against a wall on the replace of the $ from the Price dataframe.
Here is the solution as of today, nothing else worked for me - and I spent like 5 hours trying permutations of all solutions.
I could get the replace to work on the commas and the decimal points, but NOT ON the $ sign.
I don't know why the "r" makes a difference, but it does. Maybe someone with more mastery of pandas/python might be able to add context. Here's what worked:
car_sales["Price"] = car_sales["Price"].str.replace(r"$","", regex=True)

for some reason, the backslash before the $ sign in the above code line disappears once I save this comment - please enter it in your code, as otherwise the code won't work - as in backslash$

Just replace the backslash$ with a backslash, to remove the comma from the string.

Once these two replaces are done, convert to float to use as numbers for the plot() and hist() function calls:

car_sales["Price"] = car_sales["Price"].astype(float)

Hope this helps folks.

[Marcogoodie]

Think the r stands for regular syntax which nullifies special chars

Edit: Apologies, r stands for raw string, it's a python thing, more info linked here: https://gaurav-patil21.medium.com/why-do-we-use-r-in-regular-expressions-regex-52100dc7ce41

[gitjbnguyen]

For anyone having trouble with Section 6: Viewing and Selecting Data with Pandas Part 2 video

Here is the solution to the invalid escape sequence error, it involves having to convert from object to string, apply the str.replace() method, and finally converting it to the integer data type to be able to perform numeric calculations:

because Price's datatype is an object, you have to convert it to an integer.
Remove price column symbols
Convert the 'Price' column to string data type
car_sales['Price'] = car_sales['Price'].astype(str)

Now apply the .str.replace() method, use double slashes (I tried to put double backslashes in this response but it is giving me single slashes)
car_sales["Price"] = car_sales["Price"].str.replace('[\$\,\.]', '', regex=True)

Now convert it to an integer
car_sales['Price'] = car_sales['Price'].astype(int)

Optional: you want to fix your car prices to be more accurate than an inflated price
car_sales['Price'] = (car_sales['Price'].astype(int) // 100)

[mrdbourke]

Matplotlib notebook updates

General workflow

• In later (2022 onwards) versions of Jupyter Notebooks, %matplotlib inline is no longer needed, see this Stack Overflow thread for more

Trying to plot non-numeric columns

• In previous versions of matplotlib, trying to plot strings on certain axes would return an error, it now looks like it's possible (however, the plot will likely not look as good as it does when plotting numerics). For example:

# Note: In previous versions of matplotlib and pandas, have the "Price" column as a string would
# return an error
car_sales["Price"] = car_sales["Price"].astype(str)
# car_sales["Price"] = car_sales["Price"].astype(int) # Turning the Price column into an integer looks better

# Plot a scatter plot (does not look as good as with .astype(int))
car_sales.plot(x="Odometer (KM)", y="Price", kind="scatter");

Seaborn plotting styles namespace change

• Older versions of the seaborn plot style have been changed to their version number (e.g. seaborn-whitegrid -> seaborn-v0_8-whitegrid), matplotlib now recommends if you'd like seaborn styling to go directly to the seaborn API.
  • You can see the new seaborn styles namespace by using plt.style.available and then use them with plt.style.use("seaborn-v0_8-whitegrid")

[mrdbourke]

Scikit-Learn notebook updates

• plot_roc_curve = not available in Scikit-Learn 1.2+, see: The plot_roc_curve is not supported in the shown version #65
• Default number of n_estimators for RandomForestClassifier and RandomForestRegressor is now n_estimators=100, changed the notebook to reflect this as the baseline (e.g. for hyperparameter tuning, instead of going from 10 -> 100, went from 100 -> 200)
• Renamed dictionary with hyperparameters to search across with RandomizedSearchCV from grid to param_distributions
• Renamed dictionary with hyperparameters to search across with GridSearchCV from grid_2 to param_grid

RandomForestClassifier

• "max_features" parameter no longer supports "auto", options are: {“sqrt”, “log2”, None}, int or float, default=”sqrt”, see: https://scikit-learn.org/stable/modules/generated/sklearn.ensemble.RandomForestClassifier.html
• Updated RandomSearchCV section to include this, see:

# Hyperparameter grid RandomizedSearchCV will search over
param_distributions = {"n_estimators": [10, 100, 200, 500, 1000, 1200],
                       "max_depth": [None, 5, 10, 20, 30],
                       "max_features": ["sqrt", "log2", None],
                       "min_samples_split": [2, 4, 6],
                       "min_samples_leaf": [1, 2, 4]}

from sklearn.model_selection import RandomizedSearchCV, train_test_split

np.random.seed(42)

# Split into X & y
X = heart_disease.drop("target", axis=1)
y = heart_disease["target"]

# Split into train and test sets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2)

# Set n_jobs to -1 to use all available cores on your machine (if this causes errors, try n_jobs=1)
clf = RandomForestClassifier(n_jobs=-1)

# Setup RandomizedSearchCV
rs_clf = RandomizedSearchCV(estimator=clf,
                            param_distributions=param_distributions,
                            n_iter=20, # try 20 models total
                            cv=5, # 5-fold cross-validation
                            verbose=2) # print out results

# Fit the RandomizedSearchCV version of clf
rs_clf.fit(X_train, y_train);

Creation of train/validation/test set

Changed creation of train/validation/test sets from indexing to random splitting.

I find this cleaner and less prone to error.

from sklearn.metrics import accuracy_score, precision_score, recall_score, f1_score
from sklearn.model_selection import train_test_split
from sklearn.ensemble import RandomForestClassifier

# Set the seed
np.random.seed(42)

# Read in the data
heart_disease = pd.read_csv("../data/heart-disease.csv")

# Split into X (features) & y (labels)
X = heart_disease.drop("target", axis=1)
y = heart_disease["target"]

# Training and test split (70% train, 30% test)
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.3)

# Create validation and test split by spliting testing data in half (30% test -> 15% validation, 15% test)
X_valid, X_test, y_valid, y_test = train_test_split(X_test, y_test, test_size=0.5)

clf = RandomForestClassifier()
clf.fit(X_train, y_train)

# Make predictions
y_preds = clf.predict(X_valid)

# Evaluate the classifier
baseline_metrics = evaluate_preds(y_valid, y_preds)
baseline_metrics

Pipeline upgrades

• Removed "auto" from pipeline grid search dictionary (old: "model__max_features": ["auto", "sqrt"]", new: "model__max_features": ["sqrt"])
  • Full code:

pipe_grid = {
    "preprocessor__num__imputer__strategy": ["mean", "median"], # note the double underscore after each prefix "preprocessor__"
    "model__n_estimators": [100, 1000],
    "model__max_depth": [None, 5],
    "model__max_features": ["sqrt"],
    "model__min_samples_split": [2, 4]
}

4.2.1 Classification model evaluation metrics - ROC Curve

• Added code example of using sklearn.metrics.RocCurveDisplay.from_estimator (new in Scikit-Learn 1.2+), as discussed in The plot_roc_curve is not supported in the shown version #65

from sklearn.metrics import RocCurveDisplay
roc_curve_display = RocCurveDisplay.from_estimator(estimator=clf, 
                                                   X=X_test, 
                                                   y=y_test)

[gitjbnguyen]

Using this line of code results in this error:
df_large_error = df.copy()
df_large_error.iloc[0]["squared_differences"] = 16 # increase squared differences for 1 sample

You are setting values through chained assignment. Currently this works in certain cases, but when using Copy-on-Write (which will become the default behaviour in pandas 3.0) this will never work to update the original DataFrame or Series, because the intermediate object on which we are setting values will behave as a copy.
A typical example is when you are setting values in a column of a DataFrame, like:

df["col"][row_indexer] = value

Use df.loc[row_indexer, "col"] = values instead, to perform the assignment in a single step and ensure this keeps updating the original df.

But this can be fixed with this solution:
df_large_error = df.copy()
df_large_error.iloc[0, df_large_error.columns.get_loc("squared_differences")] = 16

[sithu-khant]

In the lecture Hyperparameter tuning with RandomizedSearchCV

Remove auto in max_features.

Changed in version 1.1: The default of max_features changed from "auto" to 1.0.

Read more in scikit-learn documentation: https://scikit-learn.org/stable/modules/generated/sklearn.ensemble.RandomForestRegressor.html

[sithu-khant]

Getting False in pd.api.types.is_string_dtype(df_tmp["UsageBand"])

Daniel got True in the video lecture but you will get False. That is because of the version update.

Object datatype is not considered as String datatype anymore. So, you can try like that:

pd.api.types.is_object_dtype(df_tmp["UsageBand"])

Read more here -> https://pandas.pydata.org/docs/reference/api/pandas.api.types.is_object_dtype.html

[mkchong0710]

Thanks a lot for the highlight! Really helps!

[SleepyKumiho]

I was so confused here thank you!

[mrdbourke]

TensorFlow Notebook Updates

Due to changes in workflow/TensorFlow library updates, going to remake the Dog Vision project.

This will be the latest version of TensorFlow (2.14.0, as of October 2023).

Currently the notebook will be under the end-to-end-dog-vision-v2.ipynb namespace.

See: https://github.com/mrdbourke/zero-to-mastery-ml/blob/master/section-4-unstructured-data-projects/end-to-end-dog-vision-v2.ipynb

[arpadikuma]

There's an increase in students encountering errors when installing jupyter or creating a conda env with jupyter, with Python 3.12 somehow already installed.

The error message always is something like this:

pin-1 is not installable because it requires
    python 3.12.*, which conflicts with any installable versions previously reported.
    
Pins seem to be involved in the conflict. Currently pinned specs:
 - python 3.12.* (labeled as 'pin-1')

You can install jupyter with pip: pip install jupyter

However, since Python 3.12 is still very new and the possibility of encountering compatibility issues is still high, I recommend the following:

1. create a new env with conda with just python 3.10 or 3.11
2. activate this new env
3. install the required libraries

i.e., go to the folder you want to create the env in and execute:
conda create -p ./env python=3.10 (for python 3.10, for python 3.11 replace the 10 with 11)

Then activate that env you just created
(from the same location, do conda activate ./env)

Then install the libraries you wanted to have on that env, i.e. conda install scikit-learn numpy pandas matplotlib jupyter
And any others if necessary