# HIDDEN
# Clear previously defined variables
%reset -f

# Set directory for data loading to work properly
import os
os.chdir(os.path.expanduser('~/notebooks/16'))

# HIDDEN
import warnings
# Ignore numpy dtype warnings. These warnings are caused by an interaction
# between numpy and Cython and can be safely ignored.
# Reference: https://stackoverflow.com/a/40846742
warnings.filterwarnings("ignore", message="numpy.dtype size changed")
warnings.filterwarnings("ignore", message="numpy.ufunc size changed")

import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns
%matplotlib inline
import ipywidgets as widgets
from ipywidgets import interact, interactive, fixed, interact_manual
import nbinteract as nbi

sns.set()
sns.set_context('talk')
np.set_printoptions(threshold=20, precision=2, suppress=True)
pd.options.display.max_rows = 7
pd.options.display.max_columns = 8
pd.set_option('precision', 2)
# This option stops scientific notation for pandas
# pd.set_option('display.float_format', '{:.2f}'.format)

# HIDDEN
def df_interact(df, nrows=7, ncols=7):
    '''
    Outputs sliders that show rows and columns of df
    '''
    def peek(row=0, col=0):
        return df.iloc[row:row + nrows, col:col + ncols]
    if len(df.columns) <= ncols:
        interact(peek, row=(0, len(df) - nrows, nrows), col=fixed(0))
    else:
        interact(peek,
                 row=(0, len(df) - nrows, nrows),
                 col=(0, len(df.columns) - ncols))
    print('({} rows, {} columns) total'.format(df.shape[0], df.shape[1]))

# HIDDEN
df = pd.read_csv('water_large.csv')

# HIDDEN
from collections import namedtuple
Curve = namedtuple('Curve', ['xs', 'ys'])

def flatten(seq): return [item for subseq in seq for item in subseq]

def make_curve(clf, x_start=-50, x_end=50):
    xs = np.linspace(x_start, x_end, num=100)
    ys = clf.predict(xs.reshape(-1, 1))
    return Curve(xs, ys)

def plot_data(df=df, ax=plt, **kwargs):
    ax.scatter(df.iloc[:, 0], df.iloc[:, 1], s=50, **kwargs)

def plot_curve(curve, ax=plt, **kwargs):
    ax.plot(curve.xs, curve.ys, **kwargs)

def plot_curves(curves, cols=2, labels=None):
    if labels is None:
        labels = [f'Deg {deg} poly' for deg in degrees]
    rows = int(np.ceil(len(curves) / cols))
    fig, axes = plt.subplots(rows, cols, figsize=(10, 8),
                             sharex=True, sharey=True)
    for ax, curve, label in zip(flatten(axes), curves, labels):
        plot_data(ax=ax, label='Training data')
        plot_curve(curve, ax=ax, label=label)
        ax.set_ylim(-5e10, 170e10)
        ax.legend()

    # add a big axes, hide frame
    fig.add_subplot(111, frameon=False)
    # hide tick and tick label of the big axes
    plt.tick_params(labelcolor='none', top='off', bottom='off',
                    left='off', right='off')
    plt.grid(False)
    plt.title('Polynomial Regression')
    plt.xlabel('Water Level Change (m)')
    plt.ylabel('Water Flow (Liters)')
    plt.tight_layout()

# HIDDEN
def coefs(clf):
    reg = clf.named_steps['reg']
    return np.append(reg.intercept_, reg.coef_)

def coef_table(clf):
    vals = coefs(clf)
    return (pd.DataFrame({'Coefficient Value': vals})
            .rename_axis('degree'))

# HIDDEN
X = df.iloc[:, [0]].as_matrix()
y = df.iloc[:, 1].as_matrix()

degrees = [1, 2, 8, 12]
clfs = [Pipeline([('poly', PolynomialFeatures(degree=deg, include_bias=False)),
                  ('reg', LinearRegression())])
        .fit(X, y)
        for deg in degrees]

curves = [make_curve(clf) for clf in clfs]

alphas = [0.1, 1.0, 10.0]

ridge_clfs = [Pipeline([('poly', PolynomialFeatures(degree=deg, include_bias=False)),
                        ('reg', RidgeCV(alphas=alphas, normalize=True))])
        .fit(X, y)
        for deg in degrees]

ridge_curves = [make_curve(clf) for clf in ridge_clfs]

lasso_clfs = [Pipeline([('poly', PolynomialFeatures(degree=deg, include_bias=False)),
                        ('reg', LassoCV(normalize=True, precompute=True, tol=0.001))])
        .fit(X, y)
        for deg in degrees]
lasso_curves = [make_curve(clf) for clf in lasso_clfs]

# HIDDEN
df

# HIDDEN
fig = plt.figure(figsize=(10, 4))

plt.subplot(131)
plot_data()
plot_curve(curves[3])
plt.title('Base')
plt.ylim(-5e10, 170e10)

plt.subplot(132)
plot_data()
plot_curve(ridge_curves[3])
plt.title('Ridge Regression')
plt.ylim(-5e10, 170e10)

plt.subplot(133)
plot_data()
plot_curve(lasso_curves[3])
plt.title('Lasso Regression')
plt.ylim(-5e10, 170e10)
plt.tight_layout()

# HIDDEN
ridge = coef_table(ridge_clfs[3]).rename(columns={'Coefficient Value': 'Ridge'})
lasso = coef_table(lasso_clfs[3]).rename(columns={'Coefficient Value': 'Lasso'})

pd.options.display.max_rows = 20
pd.set_option('display.float_format', '{:.10f}'.format)
display(ridge.join(lasso))
pd.options.display.max_rows = 7
pd.set_option('display.float_format', '{:.2f}'.format)