Errata in Ch2~Ch9

[rickiepark]

• p39: 4th eq. in the note
  In $ \sum_i (w_i^{{i}} x_i^{(i)} $, subscript i should be changed other character because it means sample index and remove superscript of w like: $ \sum_k (w_k x_k^{(i)} $
• p59: 4th line in first code block
  c='' raises an error in matplotlib 3.2, suggest replace facecolor='none'
• p61: 8th line
  L05_gradient-descent_slides.pdf shoud be changed L08_logistic_slides.pdf
• p63: 5th line from the bottom
  $ \phi(x) = 0.5 $ should be changed $ \phi(0) = 0.5 $
• p94: first line, 9th line
  $ 0.1 \overline{\overline{6}} $ should be changed $ 0.1 \overline{6} $
  $ 0. \overline{\overline{16}} $ should be changed $ 0.1 \overline{6} $
• p100: 10th line
  As you know, scikit-learn now can do post-pruning with ccp_alpha
• p107: In first eq.
  $ x_k^{(i)} x_k^{(j)} $ should be changed $ x_k^{(i)} - x_k^{(j)} $
• p119: 16th line and 7th line from the bottom
  (X[:, 0].reshape(-1, 1))) should be changed (X[:, 0].reshape(-1, 1))
  In c_transf.fit_transform(X).astype(float), astype(float) is not needed.
• p162: In 2nd code block
  It's better that mean_overall = mean_overall.reshape(d, 1) is moved above for loop.
• p173: note box
  $ \sum v = \lambda v $, so $ v = \frac{1}{n} \sum_{i=1}^n a^{(i)} \phi(x^{(i)}) = \lambda \phi(X)^T a $ should be changed $ v = \sum_{i=1}^n a^{(i)} \phi(x^{(i)}) = \phi(X)^T a $
• p172: last eq.
  and $ \frac{1}{n} \sum_{i=1}^n a^{(i)} \phi(x^{(i)}) $ should be changed $ \sum_{i=1}^n a^{(i)} \phi(x^{(i)}) $
• p228: 10th line from the bottom and last line
  $ C_j (J \in {0, 1}) $ should be changed $ C_j (J \in {1, 2, 3}) $
  $ 0.2 \times i_0 + 0.2 \times i_0 + 0.6 \times i_1 $ should be changed $ 0.2 \times i_0 + 0.2 \times i_0, 0.6 \times i_1 $
• p266: 8th line
  "previous equations" should refer to idf(t, d) not tf idf(t, d)
• p273: 14th line
  smooth_idf parameter does not exist in second dictionary.
• p294: 3rd line under Form validation and rendering section
  wtforms.readthedocs.org/en/latest should be changed wtforms.readthedocs.io
• p296: the line above Adding style via CSS section
  jinja.pocoo.org should be changed jinja.palletsprojects.com
• p299: last line
  flask.pocoo.org/docs/1.0/ shoud be changed flask.palletsprojects.com

Thanks. :)

[rasbt]

Thanks a lot! Will incorporate it into the next ed!

Btw regarding

p59: 4th line in first code block
c='' raises an error in matplotlib 3.2, suggest replace facecolor='none'

I think they mean c="none", I think the facecolor warning is a separate warning related to the 'x' marker.

[rasbt]

In c_transf.fit_transform(X).astype(float), astype(float) is not needed.

Inuitively, I agree with you. But removing it will results in a NumPy array of dtype=object. Might be a scikit-learn bug.

[rickiepark]

Ah.. you're right. ColumnTransformer.fit_transform() returns an array of dtype=object. An array of dtype=object is converted float64 in sklearn.utils.validation.check_array() but using astype(float) is more clear. I'm not sure this is scikit-learn bug. Thanks :)

[rasbt]

I see, thanks for the feedback!