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Commit a1483fa9 authored by Zeynep Hakguder's avatar Zeynep Hakguder
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model for pa1

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%% Cell type:markdown id: tags:
# JUPYTER NOTEBOOK TIPS
Each rectangular box is called a cell.
* ctrl+ENTER evaluates the current cell; if it contains Python code, it runs the code, if it contains Markdown, it returns rendered text.
* alt+ENTER evaluates the current cell and adds a new cell below it.
* If you click to the left of a cell, you'll notice the frame changes color to blue. You can erase a cell by hitting 'dd' (that's two "d"s in a row) when the frame is blue.
%% Cell type:markdown id: tags:
# Supervised Learning Model Skeleton
We'll use this skeleton for implementing different supervised learning algorithms. Please complete "preprocess" and "partition" methods below.
%% Cell type:markdown id: tags:
This step is for reading the dataset and for extracting features and labels. The "preprocess" function should return an *n x d* "features" array, and an *n x 1* "labels" array, where *n* is the number of examples and *d* is the number of features in the dataset. In cases where there is a big difference between the scales of features, we want to normalize the features to have values in the same range [0,1]. Since this is not the case with this dataset, we will not do normalization.
%% Cell type:code id: tags:
``` python
#TODO: GIVE!
def preprocess(feature_file, label_file):
'''
Args:
feature_file: str
file containing features
label_file: str
file containing labels
Returns:
features: ndarray
nxd features
labels: ndarray
nx1 labels
'''
# You might find np.genfromtxt useful for reading in the file. Be careful with the file delimiter,
# e.g. for comma-separated files use delimiter=',' argument.
# TODO
raise NotImplementedError
return features, labels
```
%% Cell type:markdown id: tags:
Next, you'll need to split your dataset into training, validation and test sets. The "partition" function should take as input the size of the whole dataset and randomly sample a proportion *t* of the dataset as test partition and a proportion of *v* as validation partition. The remaining will be used as training data. For example, to keep 30% of the examples as test and %10 as validation, set *t* = 0.3 and *v* = 0.1. You should choose these values according to the size of the data available to you. The "split" function should return indices of the training, validation and test sets. These will be used to index into the whole training set.
%% Cell type:code id: tags:
``` python
#TODO: GIVE!
def partition(size, t, v = 0):
'''
Args:
size: int
number of examples in the whole dataset
t: float
proportion kept for test
v: float
proportion kept for validation
Returns:
test_indices: ndarray
1D array containing test set indices
val_indices: ndarray
1D array containing validation set indices
'''
# np.random.permutation might come in handy. Do not sample with replacement!
# Be sure not to use the same indices in test and validation sets!
# use the first np.ceil(size*t) for test,
# the following np.ceil(size*v) for validation set.
# TODO
raise NotImplementedError
return test_indices, val_indices
```
%% Cell type:markdown id: tags:
In cases, where data is not abundantly available, we resort to getting an error estimate from average of error on different splits of error. In this case, every fold of data is used for testing and for training in turns, i.e. assuming we split our data into 3 folds, we'd
* train our model on fold-1+fold-2 and test on fold-3
* train our model on fold-1+fold-3 and test on fold-2
* train our model on fold-2+fold-3 and test on fold-1.
We'd use the average of the error we obtained in three runs as our error estimate. Implement function "kfold" below.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 2
def kfold(indices, k):
'''
Args:
indices: ndarray
1D array with integer entries containing indices
k: int
Number of desired splits in data.(Assume test set is already separated.)
Returns:
fold_dict: dict
A dictionary with integer keys corresponding to folds. Values are (training_indices, val_indices).
val_indices: ndarray
1/k of training indices randomly chosen and separates them as validation partition.
train_indices: ndarray
Remaining 1-(1/k) of the indices.
e.g. fold_dict = {0: (train_0_indices, val_0_indices),
1: (train_0_indices, val_0_indices), 2: (train_0_indices, val_0_indices)} for k = 3
'''
return fold_dict
```
%% Cell type:markdown id: tags:
Choice of distance metric plays an important role in the performance of *k*-NN. Let's start with implementing a distance method in the "distance" function below. It should take two data points and the name of the metric and return a scalar value.
%% Cell type:code id: tags:
``` python
#TODO: Programming Assignment 1
def distance(x, y, metric):
'''
Args:
x: ndarray
1D array containing coordinates for a point
y: ndarray
1D array containing coordinates for a point
metric: str
Euclidean, Hamming
Returns:
'''
if metric == 'Euclidean':
raise NotImplementedError
elif metric == 'Hammming':
raise NotImplementedError
else:
raise ValueError('{} is not a valid metric.'.format(metric))
return dist # scalar distance btw x and y
```
%% Cell type:markdown id: tags:
We will extend "Model" class while implementing supervised learning algorithms.
%% Cell type:code id: tags:
``` python
class Model:
# preprocess_f and partition_f expect functions
# use kwargs to pass arguments to preprocessor_f and partition_f
# kwargs is a dictionary and should contain t, v, feature_file, label_file
# e.g. {'t': 0.3, 'v': 0.1, 'feature_file': 'some_file_name', 'label_file': 'some_file_name'}
def __init__(self, preprocessor_f, partition_f, **kwargs):
self.features, self.labels = preprocessor_f(kwargs['feature_file'], kwargs['label_file'])
self.size = len(self.labels) # number of examples in dataset
self.feat_dim = self.features.shape[1] # number of features
self.val_indices, self.test_indices = partition_f(self.size, kwargs['t'], kwargs['v'])
self.val_size = len(self.val_indices)
self.test_size = len(self.test_indices)
self.train_indices = np.delete(np.arange(self.size), np.append(self.test_indices, self.val_indices), 0)
self.train_size = len(self.train_indices)
def fit(self):
raise NotImplementedError
def predict(self, test_points):
raise NotImplementedError
```
%% Cell type:markdown id: tags:
## General supervised learning performance related functions
### (To be implemented later when it is indicated in other notebooks)
%% Cell type:markdown id: tags:
Implement the "conf_matrix" function that takes as input an array of true labels (*true*) and an array of predicted labels (*pred*). It should output a numpy.ndarray.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 1
def conf_matrix(true, pred):
'''
Args:
true: ndarray
nx1 array of true labels for test set
pred: ndarray
nx1 array of predicted labels for test set
Returns:
ndarray
'''
raise NotImplementedError
tp = tn = fp = fn = 0
# calculate true positives (tp), true negatives(tn)
# false positives (fp) and false negatives (fn)
# returns the confusion matrix as numpy.ndarray
return np.array([tp,tn, fp, fn])
```
%% Cell type:markdown id: tags:
ROC curves are a good way to visualize sensitivity vs. 1-specificity for varying cut off points. Now, implement a "ROC" function that predicts the labels of the test set examples using different *threshold* values in "predict" and plot the ROC curve. "ROC" takes a list containing different *threshold* parameter values to try and returns two arrays; one where each entry is the sensitivity at a given threshold and the other where entries are 1-specificities.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 1
def ROC(model, indices, value_list):
'''
Args:
model: a fitted supervised learning model
indices: ndarray
1D array containing indices
value_list: ndarray
1D array containing different threshold values
Returns:
sens: ndarray
1D array containing sensitivities
spec_: ndarray
1D array containing 1-specifities
'''
# use predict method to obtain predicted labels at different threshold values
# use conf_matrix to calculate tp, tn, fp, fn
# calculate sensitivity, 1-specificity
# return two arrays
raise NotImplementedError
return sens, spec_
```
......
model_solution.ipynb → ProgrammingAssignment_1/model_solution.ipynb
+ 0
− 14
View file @ a1483fa9
%% Cell type:markdown id: tags:
# JUPYTER NOTEBOOK TIPS
Each rectangular box is called a cell.
* ctrl+ENTER evaluates the current cell; if it contains Python code, it runs the code, if it contains Markdown, it returns rendered text.
* alt+ENTER evaluates the current cell and adds a new cell below it.
* If you click to the left of a cell, you'll notice the frame changes color to blue. You can erase a cell by hitting 'dd' (that's two "d"s in a row) when the frame is blue.
%% Cell type:markdown id: tags:
# Supervised Learning Model Skeleton
We'll use this skeleton for implementing different supervised learning algorithms. Please complete "preprocess" and "partition" methods below.
%% Cell type:markdown id: tags:
This step is for reading the dataset and for extracting features and labels. The "preprocess" function should return an *n x d* "features" array, and an *n x 1* "labels" array, where *n* is the number of examples and *d* is the number of features in the dataset. In cases where there is a big difference between the scales of features, we want to normalize the features to have values in the same range [0,1]. Since this is not the case with this dataset, we will not do normalization.
%% Cell type:code id: tags:
``` python
def preprocess(feature_file, label_file):
'''
Args:
feature_file: str
file containing features
label_file: str
file containing labels
Returns:
features: ndarray
nxd features
labels: ndarray
nx1 labels
'''
# You might find np.genfromtxt useful for reading in the file. Be careful with the file delimiter,
# e.g. for comma-separated files use delimiter=',' argument.
# TODO
raise NotImplementedError
return features, labels
```
%% Cell type:markdown id: tags:
Next, you'll need to split your dataset into training, validation and test sets. The "partition" function should take as input the size of the whole dataset and randomly sample a proportion *t* of the dataset as test partition and a proportion of *v* as validation partition. The remaining will be used as training data. For example, to keep 30% of the examples as test and %10 as validation, set *t* = 0.3 and *v* = 0.1. You should choose these values according to the size of the data available to you. The "split" function should return indices of the training, validation and test sets. These will be used to index into the whole training set.
%% Cell type:code id: tags:
``` python
#TODO: GIVE!
def partition(size, t, v = 0):
'''
Args:
size: int
number of examples in the whole dataset
t: float
proportion kept for test
v: float
proportion kept for validation
Returns:
test_indices: ndarray
1D array containing test set indices
val_indices: ndarray
1D array containing validation set indices
'''
# np.random.permutation might come in handy. Do not sample with replacement!
# Be sure not to use the same indices in test and validation sets!
# use the first np.ceil(size*t) for test,
# the following np.ceil(size*v) for validation set.
# TODO
raise NotImplementedError
return test_indices, val_indices
```
%% Cell type:markdown id: tags:
In cases, where data is not abundantly available, we resort to getting an error estimate from average of error on different splits of error. In this case, every fold of data is used for testing and for training in turns, i.e. assuming we split our data into 3 folds, we'd
* train our model on fold-1+fold-2 and test on fold-3
* train our model on fold-1+fold-3 and test on fold-2
* train our model on fold-2+fold-3 and test on fold-1.
We'd use the average of the error we obtained in three runs as our error estimate. Implement function "kfold" below.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 2
def kfold(indices, k):
'''
Args:
indices: ndarray
1D array with integer entries containing indices
k: int
Number of desired splits in data.(Assume test set is already separated.)
Returns:
fold_dict: dict
A dictionary with integer keys corresponding to folds. Values are (training_indices, val_indices).
val_indices: ndarray
1/k of training indices randomly chosen and separates them as validation partition.
train_indices: ndarray
Remaining 1-(1/k) of the indices.
e.g. fold_dict = {0: (train_0_indices, val_0_indices),
1: (train_0_indices, val_0_indices), 2: (train_0_indices, val_0_indices)} for k = 3
'''
return fold_dict
```
%% Cell type:markdown id: tags:
Choice of distance metric plays an important role in the performance of *k*-NN. Let's start with implementing a distance method in the "distance" function below. It should take two data points and the name of the metric and return a scalar value.
%% Cell type:code id: tags:
``` python
#TODO: Programming Assignment 1
def distance(x, y, metric):
'''
Args:
x: ndarray
1D array containing coordinates for a point
y: ndarray
1D array containing coordinates for a point
metric: str
Euclidean, Hamming
Returns:
'''
if metric == 'Euclidean':
raise NotImplementedError
elif metric == 'Hammming':
raise NotImplementedError
else:
raise ValueError('{} is not a valid metric.'.format(metric))
return dist # scalar distance btw x and y
```
%% Cell type:markdown id: tags:
We will extend "Model" class while implementing supervised learning algorithms.
%% Cell type:code id: tags:
``` python
class Model:
# preprocess_f and partition_f expect functions
# use kwargs to pass arguments to preprocessor_f and partition_f
# kwargs is a dictionary and should contain t, v, feature_file, label_file
# e.g. {'t': 0.3, 'v': 0.1, 'feature_file': 'some_file_name', 'label_file': 'some_file_name'}
def __init__(self, preprocessor_f, partition_f, **kwargs):
self.features, self.labels = preprocessor_f(kwargs['feature_file'], kwargs['label_file'])
self.size = len(self.labels) # number of examples in dataset
self.feat_dim = self.features.shape[1] # number of features
self.val_indices, self.test_indices = partition_f(self.size, kwargs['t'], kwargs['v'])
self.val_size = len(self.val_indices)
self.test_size = len(self.test_indices)
self.train_indices = np.delete(np.arange(self.size), np.append(self.test_indices, self.val_indices), 0)
self.train_size = len(self.train_indices)
def fit(self):
raise NotImplementedError
def predict(self, test_points):
raise NotImplementedError
```
%% Cell type:markdown id: tags:
## General supervised learning performance related functions
### (To be implemented later when it is indicated in other notebooks)
%% Cell type:markdown id: tags:
Implement the "conf_matrix" function that takes as input an array of true labels (*true*) and an array of predicted labels (*pred*). It should output a numpy.ndarray.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 1
def conf_matrix(true, pred):
'''
Args:
true: ndarray
nx1 array of true labels for test set
pred: ndarray
nx1 array of predicted labels for test set
Returns:
ndarray
'''
raise NotImplementedError
tp = tn = fp = fn = 0
# calculate true positives (tp), true negatives(tn)
# false positives (fp) and false negatives (fn)
# returns the confusion matrix as numpy.ndarray
return np.array([tp,tn, fp, fn])
```
%% Cell type:markdown id: tags:
ROC curves are a good way to visualize sensitivity vs. 1-specificity for varying cut off points. Now, implement a "ROC" function that predicts the labels of the test set examples using different *threshold* values in "predict" and plot the ROC curve. "ROC" takes a list containing different *threshold* parameter values to try and returns two arrays; one where each entry is the sensitivity at a given threshold and the other where entries are 1-specificities.
%% Cell type:code id: tags:
``` python
# TODO: Programming Assignment 1
def ROC(model, indices, value_list):
'''
Args:
model: a fitted supervised learning model
indices: ndarray
1D array containing indices
value_list: ndarray
1D array containing different threshold values
Returns:
sens: ndarray
1D array containing sensitivities
spec_: ndarray
1D array containing 1-specifities
'''
# use predict method to obtain predicted labels at different threshold values
# use conf_matrix to calculate tp, tn, fp, fn
# calculate sensitivity, 1-specificity
# return two arrays
raise NotImplementedError
return sens, spec_
```
......
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