scala crash course

Linearseq[a] and Product with Generictraversabletemplate[a, List] with linearseqoptimized[a, List[a]) with Serializable-- Generics are widely used in Scala and can be said to be ubiquitous, and Scala can automatically infer what type ofThe abov

that the constant has access rights under the navigation package Private[ This] var speed = 200 } } Packagelaunch{ImportNavigation._ Object Vehicle {//Private[launch] Indicates that the constant is instantiated in the package launch the sibling Private[Launch] Val guide =NewNavigator} }} Read and write files in Scala, console input operations Read-write implementation of the file: Read the file with the FromFile meth

Introduction OK. The time has passed for another week. The first week has a May Day holiday, so I feel that the time is more than enough. In the middle of this week, no holiday can only be digested by evening and weekend time. In fact, it is still a little nervous! Later, we found that the video of each course also had corresponding courseware (Slide) and subtitles (subtitles) that could be downloaded. In this way, the download of video learning and o

is the return value }}//Associated Classclassuniversity{val ID=University.newstudennoPrivatevar number =0def aclass (number:int) { This. number + =Number }}a detailed description of apply in ScalaApplication in Objec: Apply method can be used in class and object, you can instantiate class in the associated object, thus calling methods in the classApplication in class: After the class is instantiated, the object () can call the Apply methodObject Applyops {def main (args:array[string]): Unit= {

, range for list2.unzip, flatten, contact, map2 example Explanation //list.apply () =list ( )println (List (1, 2, 3))//> List (1, 2, 3)//list.make Copy the same elements//List.make (3, 5)//Range left closed right openprintln (List.range (1, 5))//> List (1, 2, 3, 4)//calculates the element with a spacing of-3println (List.range (9, 1,-3))//> List (9, 6, 3)//ABCDE conversion to list after the combinationVal zipped = "ABCDE". ToList zip List (1, 2, 3, 4, 5)

= "The first" CaseNumberifNumber ==2 = "The Second" + Number Case_ = "not known number"} println (Result)"Spark!" foreach {c = =println (c match { Case' = ' and ' space ' Casech = "Char:" +ch})}This is a default task, and today we will write another study on Scala! I hope you are concerned about Liaoliang Teacher's (18610086859), he will update the big Data video every day!The latest big Data video 74 speaks: Http://pan.baidu.com/s/1hqJByvUThis artic

{override def log (msg:string) {println ("Traitlogger Log content is:" +msg)}} Trait traitloggered{def loged (msg:string) {println ("Traitloggered Log content is:" +msg)}} Trait Consoleloggerextendstraitlogger{override def log (msg:string) {println ("Log from Console:" +msg)}}In fact, learning Scala related knowledge is to be able to develop in the future to big data, now although the work is background development, but also what to understand a littl

(Fp_a.apply ( 1, 2, 3)) val fp_b = SUM (1, _: Int, 3) println (Fp_b ( 2 10)) d Ata.foreach (println _) Data.foreach (println) about closures in ScalaScala closure parsing: Let the function body implement redundant things with simple expressionsScala Closure implementation def main (args:array[string]) { = List (1, 2, 3, 4, 5, 6) = 0 + = _) = (X:int) + x + more = Add (1) = Add (9999) println (A ( )) println (b (10)Scala's functional programming is really

Share a fun web App page Crash tool of course the main is to let everyone look at his principles and look at his structure everyone should guess this. This is the use of a page after the current Div added an active, And then using the CSS to control the effect this is undoubtedly the use of the maximum width of 640 layout similar to the JS framework I have shared 2 such as fullpage.js,slip.js can be found i

performing simple statistical operations on a listLike the Max in C + +, the min function, but this three is quite powerful with traversing the entire list to find the maximum, minimum, and value.Sample code:1 digits = [1, 2, 3, 4, 5, 6, 7, 8, 9, 0]2print(min (digits))3pri NT(max (digits))4print(sum (digits))Four, list parsingThe explanation in the code parsing book is that the code for the For loop and the creation of the new element is merged into a single line and the new element is automati

ifAge :4 Print("yout Admission cost is $")5 elifAge :6 Print("Your Admission cost is $")7 Else:8 Print("Your Admission COSR is $")The only thing to note is that Python and Linux pay the shell the same, else if if is shrunk to elif.Four, using the IF statement to process the list　　1. Check for special elements　　In the For loop with an if statement, the sample code is as follows:1names = ['Peter','Mina','Mike']2 3 forNameinchnames:4 ifName = ='Peter':5 Print(Name.title ()

temporarily), it is best to use the INNER join on statement so that you never forget the type of join. Joins are made temporarily at run time, and the more associated tables consume resources, so it's not necessary to don't mess with tables It Pays to experiment As you can see, there are often more than one-to-perform any given SQL operation. And there is rarely a definitive right or wrong. Performance can affected by the type of operation, the amount of data in the tables, whether ind

) REFERENCES appearance (the corresponding primary key field name in the appearance); FK_ID is the name of the foreign key. For more foreign key related content, please refer to foreign KEY constraintsModification of complex table structuresCOMPLEX table structure changes usually require a manual move process involving these steps: Create A new table with the new column layout. Use the INSERT SELECT statement (see Chapter, "Inserting Data," for details of this statement) to copy th

Hope to learn the gospel of the Children of Learning machine, the world's largest AI company Google launched a "machine learning Crash Course", not only the whole Chinese, but also free to listen to OH. The course is 15 hours, the course is compact, so the reader friends, still need you have certain basic knowledge of

default to be within three letters. MySQL has a built-in stop word list , it's the same as the short word, of course, this can also be manually modified, specific methods can search for information, check the document. Many words appear so frequently that searching for them will be useless (returning too many results). As a result, MySQL grants 50% the rule that a word appears in 50% or more rows, which is treated as a deactivated word and is

CREATE TABLE IF not EXISTSOrderTotals (Order_numINT, totalDECIMAL(8,2)); --Open the cursor OPENordernumbers; --Loop through all rowsREPEAT--Get Order number FETCHOrdernumbers intoo; --Get The total for this orderCall OrderTotal (O,1, T); --Insert order and total into ordertotals INSERT intoordertotals (Order_num, total)VALUES(o, t); --End of LoopUNTIL DoneENDREPEAT; --Close the cursor CLOSEordernumbers;END;Who's going to do all this work? Is it a top-level application or a dat

listLet's look at the following code:1names = ['Peter','Mina','Mpeter','Katherine']2My_friends =names[:]3 4 Print('I have a list of my friends:')5 Print(names)6 Print("however Mina have a same list!")7 Print(my_friends)8 Print("But Mike just has both in my list")9Mike_friends = Names[0:2]Ten Print(mike_friends)The principle of copying a list is actually simple:　　Declares a list, and assigns a value, and then declares a list B, and then iterates through list A and passes the value to the end of

this you know what is (and the rules and restrictions that govern them), let's look at View creation: Views is created using the CREATE VIEW statement. To view the statement used to create a view, use SHOW create view viewname;. To remove a view, the DROP statement is used. The syntax is simply DROP VIEW viewname;. To update a view the DROP statement and then the CREATE statement again, or just us E Create OR replace VIEW, which would create it if it does not exist and r