Commonly seen python error messages - Learn to code Python for Beginners

• Python KeyError if dict[key]: cannot do this have to change to if key in dict: 

Pandas Sample Code - Udacity Machine Learning

• .groupby()
• .count()
• pandas.DataFrame.count
• .sum()
• df[df["class"]==1].count()["value"]
• countOfColumn = myDataFrame[conditionColumn["myCondition"]=="myCondValue"].count()["conditionColumn"] get row count by column condition and value
• pandas.Series.map
• pandas.DataFrame.count
• df[(df['A']>0) & (df['B']>0) & (df['C']>0)]
• pandas.DataFrame.sum
• df.groupby('a').count()
• df.first()

How to participate in a Kaggle competition - by Kaggle CEO youtube

Udacity Machine Learning Nanodegree Version Spaces by Georgia Tech

Udacity Machine Learning Nanodegree Bayes Rule Bayesian Analysis Walkthrough

quiz
<xi, di>
di = f(xi) + err
x, d, h(x) = x mod 9, h(x) = x/3, h(x) = 2,
1, 1, 1%9 = 1, 1/3, 2,
3, 0, 3%9 = 3,  1, 2,
6, 5, 6%9 = 6, 2, 2,
10, 2, 10%9= 1, 10/3, 2,
11, 1, 11%9= 2, 11/3, 2,
13, 4, 13%9 = 4, 13/3, 2,

sum of squared errors for each (excel calc)


h(x) = x mod 9
sum of squared errors = 12


h(x) = x/3
sum of squared errors = 19.44

h(x) = 2
sum of squared errors = 19

Use the smallest
Or better way: write a python script

R Squared Coefficient of Determination - Machine Learning Concept

*coefficient of determination*](http://stattrek.com/statistics/dictionary.aspx?definition=coefficient_of_determination)

R^2
R²

coefficient of determination
useful statistics for regression analysis
measures how good the model makes prediction.


R^2 range {0, 1}
can be negative, arbitrarily worse
percentage of square correlection between predicted and actual values of target variable

indicates what percentage of the target variable, using this model, can be explained by the **features**.


r2_score from sklearn.metrics

Pandas Numpy Data Analysis Tool Kit - Udacity Machine Learning Nanodegree 01

Numpy perfect for statistical analysis, matrix manipulation. Learn to Code Notes.
Numpy Documentation
https://docs.scipy.org/doc/numpy-dev/user/quickstart.html

Code pattern 01 numpy use array().T to get matrix transpose
Example:
X = [1,2,3]
XT = array(X).T

numpy.dot(series1, series2)