Index Error Handling: A Comprehensive Guide to ArgumentOutOfRangeException

by Liudmyla Shuvalova | Sep 12, 2023 | blog

ArgumentOutOfRangeException: Handling Index Errors in Arrays and Collections

ArgumentOutOfRangeException is an exception that is commonly encountered in programming, particularly in languages like C# and .NET. The exception known as ArgumentOutOfRangeException is triggered when a method receives an argument that is neither null nor falls within the expected range of values. This particular exception type possesses the attributes ParamName and ActualValue, which aid in comprehending the underlying cause of the exception.

What are ParamName and ActualValue?

The ParamName attribute identifies the name of the parameter associated with the erroneous argument, while the ActualValue attribute pinpoints the flawed value, should one be present.

Where ArgumentOutOfRange is widely employed?

Typically, the occurrence of the ArgumentOutOfRangeException is attributable to developer oversight. If the argument’s value is sourced from a method call or user input before being passed to the method that generates the exception, it is advisable to perform argument validation prior to the method invocation.

This exception can occur in various situations, depending on the specific context in which it is used. Some common scenarios include:

Array or Collection Index: When trying to retrieve an element from an array or collection using an index that exceeds the array or collection’s boundaries.
String Manipulation: When working with strings, this exception may be thrown if an attempt is made to access a character at an index that does not exist within the string.
Numeric Ranges: In mathematical or numerical operations, this exception may be raised if a number is outside the acceptable range for a given operation. For example, attempting to take the square root of a negative number may trigger this exception.
Custom Validation: Developers can also throw ArgumentOutOfRangeException explicitly in their code when implementing custom validation logic for function or method parameters.

The ArgumentOutOfRangeException is widely employed by classes within the System.Collections namespace. A common scenario arises when your code attempts to remove an item at a specific index from a collection. If the collection is either empty or the specified index, as provided through the argument, is negative or exceeds the collection’s size, this exception is likely to ensue.

How Do Developers Handle ArgumentOutOfRangeException?

To handle this exception, developers can use try-catch blocks to catch and respond to it appropriately. When caught, the application can provide an error message or take corrective action, such as prompting the user for valid input or logging the issue for debugging purposes.

Here are examples of ArgumentOutOfRangeException:

using System;
using System.Collections.Generic;

class Program
{
  static void Main(string[] args)
  {
    try
    {
      var nums = new List<int>();
      int index = 1;
      Console.WriteLine("Trying to remove number at index {0}", index);

      nums.RemoveAt(index);
    }
    catch (ArgumentOutOfRangeException ex)
    {
      Console.WriteLine("There is a problem!");
      Console.WriteLine(ex);
    }
  }
}

/* Output:
Trying to remove number at index 1
There is a problem!
System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')
   at System.Collections.Generic.List`1.RemoveAt(Int32 index)
   at Program.Main(String[] args) in \C#\ConsoleApp1\Program.cs:line 14 */

In order to preempt the exception, we can verify whether the Count property of the collection exceeds zero, and that the specified index for removal is likewise less than the value stored in Count. Only then should we proceed with the removal of a member from the collection. We shall modify the code statement within the try block as follows:

var nums = new List<int>() { 10, 11, 12, 13, 14 };
var index = 2;
Console.WriteLine("Trying to remove number at index {0}", index);

if (nums.Count > index && 0 < nums.Count)
{
nums.RemoveAt(index);
Console.WriteLine("Number at index {0} successfully removed", index);
}

/* Output:
Trying to remove number at index 2
Number at index 2 successfully removed
*/

In summary, ArgumentOutOfRangeException serves as a valuable exception for managing situations in which an argument’s value deviates from the anticipated range. It assumes a pivotal role in maintaining the strength and dependability of software by affording developers the capability to detect and address improper input in a graceful manner, thereby averting unforeseen system failures or erroneous operations.

Empowering Python: Numarable Options to Enumarate Square Numbers

by Liudmyla Shuvalova | Aug 24, 2023 | blog

Exploring The Python’s Square Number Calculation

A square arises when you take a number and multiply it by itself. This multiplication happens only once, as in: n multiplied by n. This operation is equivalent to elevating a number to the second power. Python offers multiple methods for calculating the square of a number.

Every method provides an accurate solution, without any being superior to the rest. Simply select the one that resonates with you the most.

Square Number With Multiplication

A square represents a number that is the outcome of being multiplied by itself. Another way to achieve this result is by using the * symbol for direct multiplication. For instance, when we want to find the square of 4, we perform the following code:

num = 4
square = num * num
print("Square number of", num, "is", square)

# Output: Square number of 4 is 16

Square Number With Exponent Operator **

Another technique for calculating the square of a number involves Python’s exponentiation (**) operator. The twin asterisks trigger Python’s exponentiation operation. To obtain a squared value, we can raise it to the power of 2. Hence, we input the number to be squared, followed by **, and conclude with 2. To illustrate, when seeking the square of 4, the code is as follows:

num = 4
square = num ** 2
print("Square number of", num, "is", square)

# Output: Square number of 4 is 16

Square Number With Pow() Function

An additional method to compute the square of numbers involves using the built-in pow() function. This function raises a given value to a designated power. The initial parameter denotes the number requiring elevation, while the subsequent parameter signifies the exponent. In the case of squaring via pow(), the exponent is consistently set as 2. For instance, when the aim is to square 4, the procedure unfolds as:

num = 4
square = pow(num, 2)
print("Square number of", num, "is", square)

# Output: Square number of 4 is 16

Square Number With Math.pow() Function

Another option for obtaining the square of a number is through the utilization of the math.pow() function. This function takes identical inputs, but generates a floating-point outcome.
So the code will resemble this:

import math

num = 4
square = math.pow(num, 2)
print("Square number of", num, "is", square)

# Output: Square number of 4 is 16.0

Square Values In List or Array

The earlier instances solely concerned squaring individual values independently. Nevertheless, there are instances when we come across a list or array containing values that require squaring collectively. Let’s explore a pair of potential methods for achieving this.

Square With List Comprehension

A method available to square a sequence of values involves employing a list comprehension. These operations are streamlined and necessitate only minimal code. The following illustrates how a list comprehension can execute squaring for each value within a list:

nums = [
4, 9, 14, 6, 2,
43, 7, 82
]
# Create list with each value squared
squared = [num ** 2 for num in nums]

print("Values:\n", nums)
print("Values squared:\n", squared)

# Output:
# Values:
# [4, 9, 14, 6, 2, 43, 7, 82]
# Values squared:
# [16, 81, 196, 36, 4, 1849, 49, 6724]

If retaining the original values is unnecessary, a list comprehension can directly replace the existing list with squared values. This is accomplished by assigning the outcome of the list comprehension back to the list itself. You need to calculate the square of each element in the ‘numbers’ list, and update the original list with these squared values. For example:

nums = [
4, 9, 14, 6, 2,
43, 7, 82
]
# Create list with each value squared
numbers = [num ** 2 for num in nums]

print("Values squared:\n", nums)

# Output:
# Values squared:
# [4, 9, 14, 6, 2, 43, 7, 82]

nums = [
4, 9, 14, 6, 2,
43, 7, 82
]
# Create list with each value squared
squared = []
for num in nums:
squared.append(num ** 2)

print("Values:\n", nums)
print("Values squared:\n", squared)

# Output:
# Values:
# [4, 9, 14, 6, 2, 43, 7, 82]
# Values squared:
# [16, 81, 196, 36, 4, 1849, 49, 6724]

In the prior approach, we retained squared values within a new list. However, if preserving the initial list is unnecessary, it’s possible to directly replace it with squared values. When utilizing a for loop for this purpose, Python’s enumerate() function becomes particularly useful, allowing us to access both the value and its index. You need to Iterate over the original ‘numbers’ list, squaring each individual number and subsequently updating the original list with these squared values. For instance:

nums = [
4, 9, 14, 6, 2,
43, 7, 82
]
for index, num in enumerate(nums):
nums[index] = num ** 2

print("Values squared:\n", nums)

# Output:
# Values squared:
# [16, 81, 196, 36, 4, 1849, 49, 6724]

Mastering Lasso Regression in Python: From Theory to Practice

by Liudmyla Shuvalova | Aug 17, 2023 | blog

Discovering Lasso Regression Python

Lasso regression stands as a noteworthy machine learning algorithm that not only facilitates linear regression but also effectively curtails the array of features incorporated within the model.

Also recognized as L1-norm regularization, Lasso regression integrates a penalty term into the cost function, proportionally linked to the cumulative absolute coefficients. This deliberate inclusion prompts the model to singularly favor the utmost crucial attributes while relegating the coefficients of lesser significance to a value of zero. Lasso regression operates as an augmentation of linear regression, introducing a regularization parameter multiplied by the summation of absolute weight values, which is subsequently amalgamated into the loss function of the conventional least squares technique.

In comparison to alternative regularization approaches like Ridge regression, which employs L2 regularization, Lasso regression claims an edge in yielding sparse solutions—instances where only a subset of features is embraced by the model. This innate trait renders Lasso regression a favored avenue for endeavors involving feature selection and the scrutiny of data entrenched within high-dimensional spaces.

However, a drawback associated with Lasso regression materializes in scenarios where the number of features eclipses the number of samples. The mechanism employed by Lasso regression to nullify certain attributes by relegating their coefficients to zero can be counterproductive when dealing with an expansive set of features.

What is Lasso?

Lasso stands for least absolute shrinkage and selection operator. Pay attention to the words, “least absolute shrinkage” and “selection”. We will refer to it shortly.
Lasso regression is used in machine learning to prevent overfitting. It is also used to select features by setting coefficients to zero.

What is Regression?

Regression, when it comes to statistics and machine learning, is a way to figure out how things are connected. You take some things that might affect something else, and you try to find out how much they actually do. The main point of this kind of math is to see how changes in one thing are connected to changes in another. It’s like trying to predict what will happen based on certain factors.

The thing you’re trying to figure out or predict is called the “outcome.” And the factors that might be influencing it are called “independent variables.” This math helps you put numbers on how these things are linked.

There are different methods to do this math, but two big ones are:
Linear Regression: This is like drawing a straight line that fits the data. The idea is to find the best line that gets really close to the real points. A problem with linear regression is that estimated coefficients of the model can become large, making the model sensitive to inputs and possibly unstable.
Logistic Regression: This sounds complicated, but it’s just used to tell whether something is one thing or another. Like, if you have data about whether it’s sunny or rainy and you want to predict the weather for tomorrow.

Other ways to do this math include using curved lines (polynomial regression), adding some rules to avoid getting too crazy (ridge and lasso regression), and even fancier methods like support vector regression and random forest regression.

In simple terms, regression is a basic tool to understand how things are linked, make guesses about the future, and get some smart insights from numbers.

Lasso Regression Python Example

In Python, Lasso regression can be executed through the employment of the Lasso class found within the sklearn.linear_model library.

Lasso Regression in Python Using Sklearn Library

#imports necessary libraries from scikit-learn
from sklearn import datasets
from sklearn.model_selection import train_test_split
from sklearn.linear_model import Lasso
from sklearn.metrics import mean_squared_error
from sklearn.preprocessing import StandardScaler

# Load the diabetes dataset
diabetes_data = datasets.load_diabetes()

# Split the data into training and test sets
X_train_orig, X_test_orig, y_train_orig, y_test_orig = train_test_split(diabetes_data.data, diabetes_data.target, test_size=0.3, random_state=42)

# Scale the data using StandardScaler
data_scaler = StandardScaler()
X_train_scaled = data_scaler.fit_transform(X_train_orig)
X_test_scaled = data_scaler.transform(X_test_orig)

# Fit Lasso regression model
lasso_reg = Lasso(alpha=0.1)
lasso_reg.fit(X_train_scaled, y_train_orig)

# Evaluate model performance on the test set
y_pred = lasso_reg.predict(X_test_scaled)

# Model Score
model_score = lasso_reg.score(X_test_scaled, y_test_orig)
print("Model Score: ", model_score)

# Lasso Coefficients
lasso_coefficients = lasso_reg.coef_

Here, the code imports various modules from scikit-learn: datasets for loading datasets, train_test_split for splitting data into training and test sets, Lasso for creating a Lasso regression model, mean_squared_error for calculating the mean squared error, and StandardScaler for data scaling. The code loads the diabetes dataset using scikit-learn’s built-in load_diabetes() function. Then we create a StandardScaler instance to standardize the feature data. The training features (X_train_orig) are fitted to the scaler to compute mean and standard deviation, and then both training and test features are scaled using these statistics. The code predicts the target values using the trained Lasso model on the scaled test features (X_test_scaled). The model’s performance is evaluated using the .score() method, which calculates the coefficient of determination (R^2) between predicted and true values. The score is printed to the console.
The code prints the R-squared model score to assess the performance. The Lasso coefficients (regression coefficients) are stored in the lasso_coefficients variable.

So here we showed how to load a dataset, split it into training and test sets, scale the features, train a Lasso regression model, evaluate its performance, and extract the model’s coefficients using scikit-learn.

Making Lasso Regression Using Numpy Library and CSV Files

Let’s introduce the housing dataset. The housing dataset is a standard machine learning dataset comprising 506 rows of data with 13 numerical input variables and a numerical target variable.

Using a test harness of repeated stratified 10-fold cross-validation with three repeats, a naive model can achieve a mean absolute error (MAE) of about 6.6. A top-performing model can achieve a MAE on this same test harness of about 1.9. This provides the bounds of expected performance on this dataset.
Mean Absolute Error (MAE) is a common metric used to measure the accuracy of a predictive model, particularly in regression tasks.

The dataset involves predicting the house price given details of the house suburb in the American city of Boston.

Here is an example:

# Import necessary libraries
import pandas as pd
import matplotlib.pyplot as plt

# Load the housing dataset
example_data = pd.read_csv("example.csv", header=None)

# Display the shape of the dataset
print(example_data.shape)

# Display the first few rows of the dataset
print(example_data.head())

#Output:
#(475, 14)
# 0 1 2 3 4 5 ... 8 9 10 11 12 13
#0 0.01 18.0 2.31 0 0.54 6.58 ... 1 296.0 15.3 396.90 4.98 24.0
#1 0.03 0.0 7.07 0 0.47 6.42 ... 2 242.0 17.8 396.90 9.14 21.6
#2 0.03 0.0 7.07 0 0.47 7.18 ... 2 242.0 17.8 392.83 4.03 34.7
#3 0.03 0.0 2.18 0 0.46 7.00 ... 3 222.0 18.7 394.63 2.94 33.4
#4 0.07 0.0 2.18 0 0.46 7.15 ... 3 222.0 18.7 396.90 5.33 36.2

The example downloads and loads the dataset as a Pandas DataFrame and summarizes the shape of the dataset and the first five rows of data.

Next we provide an implementation of the Lasso penalized regression algorithm via the Lasso class and scikit-learn Python machine learning library.

We can evaluate the Lasso Regression model on the housing dataset using repeated 10-fold cross-validation and report the average mean absolute error (MAE) on the dataset.

# Import necessary libraries
import numpy as np
import pandas as pd
from sklearn.model_selection import cross_val_score, RepeatedKFold
from sklearn.linear_model import Lasso

# Load the housing dataset
data_df = pd.read_csv("example.csv", header=None)
data = data_df.values
X_features, y_target = data[:, :-1], data[:, -1]

# Define the Lasso regression model
lasso_model = Lasso(alpha=1.0)

# Define the cross-validation strategy
cv_strategy = RepeatedKFold(n_splits=10, n_repeats=3, random_state=1)

# Evaluate the model using cross-validation
neg_mean_absolute_errors = cross_val_score(lasso_model, X_features, y_target, scoring='neg_mean_absolute_error', cv=cv_strategy, n_jobs=-1)

# Convert negative errors to positive
pos_mean_absolute_errors = np.absolute(neg_mean_absolute_errors)

# Calculate and print mean and standard deviation of positive MAE scores
mean_mae = np.mean(pos_mean_absolute_errors)
std_mae = np.std(pos_mean_absolute_errors)
print('Mean Absolute Error (MAE): %.3f (%.3f)' % (mean_mae, std_mae))

#Output:
#Mean Absolute Error (MAE): 3.711 (0.549)

Confusingly, the lambda term can be configured via the “alpha” argument when defining the class. The default value is 1.0 or a full penalty.

Running the example evaluates the Lasso Regression algorithm on the dataset and reports the average MAE across the three repeats of 10-fold cross-validation.

Your specific results may vary given the stochastic nature of the learning algorithm. Consider running the example a few times.

In this case, we can see that the model achieved a MAE of about 3.711.

Lasso Regression Prediction in Python

We may decide to use the Lasso Regression as our final model and make predictions on new data.
This can be achieved by fitting the model on all available data and calling the predict() function, passing in a new row of data.

We can demonstrate this with a complete example, listed below.

# Import necessary libraries
from pandas import read_csv as load_csv
from sklearn.linear_model import Lasso as LassoRegression

# Access the dataset from its digital realm
data_table = load_csv("example.csv", header=None)
dataset = data_table.values
input_data, target = dataset[:, :-1], dataset[:, -1]

# Craft the Lasso of Regression
regressor = LassoRegression(alpha=1.0)

# Infuse the model with insights from the dataset
regressor.fit(input_data, target)

# Define new data for a prophecy
new_sample = [0.00632, 18.00, 2.310, 0, 0.5380, 6.5750, 65.20, 4.0900, 1, 296.0, 15.30, 396.90, 4.98]

# Evoke the predictive powers
prediction = regressor.predict([new_sample])

# Reveal the outcome of the prediction
print('Oracle Predicts: %.3f' % prediction)

#Output:
#Oracle Predicts: 30.998

Running the example fits the model and makes a prediction for the new rows of data.

Your specific results may vary given the stochastic nature of the learning algorithm. Try running the example a few times.

Next, we can look at configuring the model hyperparameters.

Changing Lasso Hyperparameters in Python

We are aware that the alpha hyperparameter’s default value is set at 1.0. However, it is considered a prudent approach to experiment with an array of diverse setups and unveil the configuration that optimally suits our dataset.

Changing Config by GridSearchCV in Python

One approach would be to gird search alpha values from perhaps 1e-5 to 100 on a log-10 scale and discover what works best for a dataset. Another approach would be to test values between 0.0 and 1.0 with a grid separation of 0.01. The example below demonstrates this using the GridSearchCV class with a grid of values we have defined.

# Perform a grand quest for optimal hyperparameters with Lasso Regression
from numpy import arange as create_range
from pandas import read_csv as acquire_data
from sklearn.model_selection import GridSearchCV
from sklearn.model_selection import RepeatedKFold
from sklearn.linear_model import Lasso as TheLasso

# Unearth the dataset from its digital realm
data_scroll = acquire_data("example.csv", header=None)
data_treasures = data_scroll.values
X_marks_the_features, y_guards_the_target = data_treasures[:, :-1], data_treasures[:, -1]

# Summon the Lasso of Modeling
model_of_choice = TheLasso()

# For the art of evaluation, a method is designated
folded_kingdoms = RepeatedKFold(n_splits=10, n_repeats=3, random_state=1)

# Crafting a grid of possibilities
hyperparam_grid = dict()
hyperparam_grid['alpha'] = create_range(0, 1, 0.01)

# Initiating the grand hunt
hyperparam_hunt = GridSearchCV(model_of_choice, hyperparam_grid, scoring='neg_mean_absolute_error', cv=folded_kingdoms, n_jobs=-1)

# Commencing the search across realms
results_of_quest = hyperparam_hunt.fit(X_marks_the_features, y_guards_the_target)

# Unveiling the secrets
print('Mystical MAE: %.3f' % results_of_quest.best_score_)
print('Optimal Configurations: %s' % results_of_quest.best_params_)

#Output:
#Mystical MAE: -3.379
#Optimal Configurations: {'alpha': 0.01}

In this case, we can see that we achieved slightly better results than the default 3.379 vs. 3.711. Ignore the sign; the library makes the MAE negative for optimization purposes.
We can see that the model assigned an alpha weight of 0.01 to the penalty.

Changing Alpha Using LassoCV Class in Python

The scikit-learn library also equips us with an integrated version of the algorithm that effortlessly seeks optimal hyperparameters through the LassoCV class.

To employ this class, the model is seamlessly merged with the training dataset in the conventional manner. During this union, the hyperparameters undergo a clandestine metamorphosis, orchestrated by the enigmatic currents of training. The fit model can then be used to make a prediction.

As a default course of action, the LassoCV class embarks on an exhaustive pilgrimage, exploring the model’s efficacy across a collection of 100 alpha values. We can change this to a grid of values between 0 and 1 with a separation of 0.01 as we did in the previous example by setting the “alphas” argument.

The example below demonstrates this.

# Utilize the Lasso Regression algorithm with automatic configuration
from numpy import arange as create_sequence
from pandas import read_csv as load_data
from sklearn.linear_model import LassoCV as AutoLasso
from sklearn.model_selection import RepeatedKFold as CyclicFolds

# Obtain the dataset from its digital repository
data_table = load_data("example.csv", header=None)
data_store = data_table.values
input_data, target_values = data_store[:, :-1], data_store[:, -1]

# Determine the model evaluation approach
iterating_folds = CyclicFolds(n_splits=10, n_repeats=3, random_state=1)

auto_reg_model = AutoLasso(alphas=create_sequence(0, 1, 0.01), cv=iterating_folds, n_jobs=-1)

auto_reg_model.fit(input_data, target_values)

print('Optimal alpha: %f' % auto_reg_model.alpha_)

# Output:
# Optimal alpha: 0.000000

Executing the illustration involves training the model and unearthing the hyperparameters that yield the finest outcomes through the utilization of cross-validation.
Your specific results may vary given the stochastic nature of the learning algorithm. Try running the example a few times.
In this case, we can see that the model chose the hyperparameter of alpha=0.0. This is different from what we found via our manual grid search, perhaps due to the systematic way in which configurations were searched or selected.

Meta’s New Open Source AI Model – Now Free

by Liudmyla Shuvalova | Aug 15, 2023 | News

New Open-Source AI Model From Meta and Microsoft

The founder of Facebook and Instagram, Meta, and Microsoft has created a new artificial intelligence language model LIama 2, which is open source and will be publicly available for both research and business. Before this, Meta released a previous version of AI that was only available to approved organizations, but then the data was leaked, and LIama appeared on the network as publicly accessible. Meta tried to fight the situation and remove LLS from the Internet, for example, from the GitHub site, but LIama had already spread widely, and this was unsuccessful. After that, Meta decided to make this AI open.

Microsoft will make LIama available through the Azure AI catalog to work with it in the cloud. It will also be possible to work with AI on Windows through external providers AWS and Hugging Face. In fact, it is now the first major open-source LLM and is a competitive alternative to the expensive models of OpenAI and Google. According to Mark Zuckerberg, he sees the role of open-source technologies as key to the development of technologies in the future.

In addition to being open source in the new AI model, Meta has worked to improve security and fault tolerance. This has been implemented with Red-Teaming technologies that address security gaps. In addition, pre-trained models of this version of LLM have been trained on trillions of tokens, while fine-tuned models have been trained on a million human annotations.

It can be argued that now in IT technologies, there are 2 trends – these are AI and open-source products. Each of them has already captured the minds and attention of developers and companies around the world. An attempt to combine these 2 trends is probably an important step and impetus on the way to a new round of future technology development.

Apple No Longer Allows Usage of App APIs for Free

by Liudmyla Shuvalova | Aug 11, 2023 | News

Apple Won’t Let Apps in App Store Without API Explanation

Apple has released information that it will be even more thorough in reviewing applications before adding them to the App Store. This time the restrictions will affect the API, and now the developer will have to give detailed explanations of why he wants to use some of them. The changes will take effect in the spring of 2024 and will affect about 30 different APIs.

The changes will apply not only to new applications but also to old ones. Developers of existing applications will have to provide detailed comments, and if Apple is not satisfied with them, then the applications will be disabled. This innovation has already caused concern among developers and companies, but Apple explains this measure by the need to increase user security.

Some APIs will now be called “Required Reason API” and if they were used in the application, the developer will receive a notification from Apple asking them to explain why they used them. The first notifications will start coming in the fall after the release of iOS 17, tvOS 17, watchOS 10, and macOS Sonoma.

Some APIs can collect user data via fingerprints, such as an IP address, browser, screen resolution, and many others. This is what Apple considers a vulnerability, and it is trying to prevent user data from being leaked. However, there are fears that developers will stop publishing their applications. For example, because the restrictions will be applied by the popular UserDefaults API, which has been massively used in application development. Apple says it will provide an opportunity to appeal a decision on rejected apps, but the already hard process of publishing them in the App Store will become even more difficult.