Tutorial by Examples: me

Method references allow predefined static or instance methods that adhere to a compatible functional interface to be passed as arguments instead of an anonymous lambda expression. Assume that we have a model: class Person { private final String name; private final String surname; ...

hash( (1, 2) ) # ok hash( ([], {"hello"}) # not ok, since lists and sets are not hashabe Thus a tuple can be put inside a set or as a key in a dict only if each of its elements can. { (1, 2) } # ok { ([], {"hello"}) ) # not ok

Many developers like to customize the font, text, and background color of their IDE's. You can do this in Xcode by opening the app preference pane, either by going to XCODE->Preferences, or by pressing '⌘,' With the preference pane open you can click on the 'Fonts and Colors' tab. From her...

Any class can configure its own string formatting syntax through the __format__ method. A type in the standard Python library that makes handy use of this is the datetime type, where one can use strftime-like formatting codes directly within str.format: >>> from datetime import datetime &...

WITH CTE (StudentId, Fname, LName, DOB, RowCnt) as ( SELECT StudentId, FirstName, LastName, DateOfBirth as DOB, SUM(1) OVER (Partition By FirstName, LastName, DateOfBirth) as RowCnt FROM tblStudent ) SELECT * from CTE where RowCnt > 1 ORDER BY DOB, LName This example uses a Common Table ...

// Calculate what day of the week is 36 days from this instant. System.DateTime today = System.DateTime.Now; System.TimeSpan duration = new System.TimeSpan(36, 0, 0, 0); System.DateTime answer = today.Add(duration); System.Console.WriteLine("{0:dddd}", answer);

Add days into a dateTime object. DateTime today = DateTime.Now; DateTime answer = today.AddDays(36); Console.WriteLine("Today: {0:dddd}", today); Console.WriteLine("36 days from today: {0:dddd}", answer); You also can subtract days passing a negative value: DateTime today...

double[] hours = {.08333, .16667, .25, .33333, .5, .66667, 1, 2, 29, 30, 31, 90, 365}; DateTime dateValue = new DateTime(2009, 3, 1, 12, 0, 0); foreach (double hour in hours) Console.WriteLine("{0} + {1} hour(s) = {2}", dateValue, hour, ...

string dateFormat = "MM/dd/yyyy hh:mm:ss.fffffff"; DateTime date1 = new DateTime(2010, 9, 8, 16, 0, 0); Console.WriteLine("Original date: {0} ({1:N0} ticks)\n", date1.ToString(dateFormat), date1.Ticks); DateTime date2 = date1.AddMilliseconds(1); Console....

DateTime date1 = new DateTime(2009, 8, 1, 0, 0, 0); DateTime date2 = new DateTime(2009, 8, 1, 12, 0, 0); int result = DateTime.Compare(date1, date2); string relationship; if (result < 0) relationship = "is earlier than"; else if (result == 0) relationship = "is the...

const int July = 7; const int Feb = 2; int daysInJuly = System.DateTime.DaysInMonth(2001, July); Console.WriteLine(daysInJuly); // daysInFeb gets 28 because the year 1998 was not a leap year. int daysInFeb = System.DateTime.DaysInMonth(1998, Feb); Console.WriteLine(daysInFeb); // daysIn...

Add years on the dateTime object: DateTime baseDate = new DateTime(2000, 2, 29); Console.WriteLine("Base Date: {0:d}\n", baseDate); // Show dates of previous fifteen years. for (int ctr = -1; ctr >= -15; ctr--) Console.WriteLine("{0,2} year(s) ago:{1:d}", ...

Elements come with angle brackets are the most prominent building block of XML. Elements can either be empty, in which case they are made of an empty tag (notice the ending slash): <an-empty-element/> Or they can have content, in which case they have an opening tag (no slash) and a closin...

Extension methods are useful to extend the behaviour of libraries we don't own. They are used similar to instance methods thanks to the compiler's syntactic sugar: Sub Main() Dim stringBuilder = new StringBuilder() 'Extension called directly on the object. stringBuilder.AppendIf(t...

A good use of extension method is to make the language more functional Sub Main() Dim strings = { "One", "Two", "Three" } strings.Join(Environment.NewLine).Print() End Sub <Extension> Public Function Join(strings As IEnumerable(Of String), separa...

A namespace is a URI, but to avoid verbosity, prefixes are used as a proxy. In the following example, the prefix my-prefix is bound to the namespace http://www.example.com/my-namespace by using the special attribute xmlns:my-prefix (my-prefix can be replaced with any other prefix): <?xml versio...

In XML, element and attribute names live in namespaces. By default, they are in no namespace: <?xml version="1.0"?> <foo attr="value"> <!-- the foo element is in no namespace, neither is the attr attribute --> </foo>

import pandas as pd Create a DataFrame from a dictionary, containing two columns: numbers and colors. Each key represent a column name and the value is a series of data, the content of the column: df = pd.DataFrame({'numbers': [1, 2, 3], 'colors': ['red', 'white', 'blue']}) Show contents of d...

Create a DataFrame of random numbers: import numpy as np import pandas as pd # Set the seed for a reproducible sample np.random.seed(0) df = pd.DataFrame(np.random.randn(5, 3), columns=list('ABC')) print(df) # Output: # A B C # 0 1.764052 0.400157 0.9787...

Single line comments are preceded by --, and go until the end of the line: SELECT * FROM Employees -- this is a comment WHERE FName = 'John'