r - When does is.vector() return true? -

-

I am relatively new to R. When reading documents, the following sentence confuses me

is.vector () does not test that any object is a vector. Instead it only gives TRUE if there is no attribute other than the object name.

TRUE TRUE back to is.vector () list can be a good reference < / P>

When is is.vector () correct?

is.vector () does not test that any The object is a vector, instead it gives the TRUE , only if the object is not different from the name with a feature.

The quote means what it says. Why says that what he says is more subtle.

All R objects are linked to a list of "attributes", which attributes () for the entire list) attr () (individual attributes with for. In fact, the square of an object is actually a special feature that generic (S3) functions use to determine which method to use.

This property is "silent" in most cases, but it is visible na.omit () function (try x c; (1 , NA); y & lt; - na.omit (x); print (y) with the output to see how it can look). Here, y has an attribute, na.action , which is an object with an attribute, class . z and look at its properties with attributes (z) and then atr (z, "Class") .

When there is a class attribute, R uses the R to overwrite the square of the underlying object; In this case, the do not leave class overrides the internal integer class. Try etter (z, "square") & lt; - NULL; Square (z) . Note that this is done directly under the class (z) & lt; - Specify z directly with code by typing NULL

; - attr (y, "na .action") Try again is.vector (z) . Then remove your class from NULL and then try again is.vector (z) . It is expected that it should be clarified that the check for is.vector is the fact that a particular use of the class attribute in method transmission is irrelevant. In fact, you can do the same thing for y : try is.vector (y) , is.vector (x [! Is.na (X)] .

The reason for this criterion is that many objects in R, which do not look or function like vectors, are stored internally as vectors. Matrix is ​​in this category. Try something like x & lt; - Matrix (1: 4, 2); dput (x) . You will see that x internally As vector 1: 4 .dim with special code. This feature is hidden and inaccessible; try attr (x, ".dim") .

< P> It has all been written in the R manual (where I had seen it before), but I do not remember what section.


Comments

Post a Comment

Popular posts from this blog

java - Can't add JTree to JPanel of a JInternalFrame -

-
Image
There are two panels in my JInternalframe. I want to add TopPanel to Jtree to nominate another. But I can not add Jaitari to the top of the panel. Please help me in this piece of code: DefaultMutableTreeNode root = new DefaultMutableTreeNode ("deck"); DefaultMutableTreeNode Item Clubs = New DefaultMutableTreeNode ("Club"); AddAllCard (itemClubs); Root.add (itemClubs); DefaultMutableTreeNode item = New DefaultMutableTreeNode ("Diamonds"); AddAllCard (itemDiamonds); Root.add (itemDiamonds); DefaultMutableTreeNode Itemspads = New DefaultMutableTreeNode ("Spades"); AddAllCard (itemSpades); Root.add (itemSpades); DefaultMutableTreeNode item increases = new DefaultMutableTreeNode ("heart"); AddAllCard (itemHearts); Root.add (itemHearts); Default Trimodel Tree Model = New DefaultTreeModel (Route); Tree = new jetty (tree modal); ScrollPane = new JScrollPane (tree); // scrollPane.setViewportView (tree); . ScrollPane.getViewport () add (tr
Read more

javascript - data.match(var) not working it seems -

-
OK, I have this small block code, which is to scanned a number on the website, but for some reason There is a hip that it is not scanning at all. var regenges = / \ & lt; Span class = "currency-robux" data-to-"item-private-value-price" & gt; ([\ D,]) \ & LT; \ / Span \ & gt; /; Var ValueCiling = Data. Match (reggae); Value-song = number (value slicing location (",", "")); Is there anything wrong with that? This is related to the if statement if (value sling and lieutenant; = price watching) { < P> A function calls to move from there, but for some reason it does not seem to run at all. So I think the Regex is wrong but I'm not sure how. (There is a variable in PriceWinking , this is a snippet from the code.) On the website, I'm trying to remove it. & lt; Span class = "robux" data-plus = "item-privatesale-price" & gt; 115 & lt; / Span & gt; Keep in mind
Read more

javascript - How can I pause a jQuery .each() loop, while waiting for user input? -

-
Before I continue to get a jQuery .each loop to wait for user input There is a problem in repeatedly repeating This is my code (I have commented on what I would like to do): & lt; Html xmlns = "http://www.w3.org/1999/xhtml" & gt; & Lt; Top & gt; & Lt; Link rel = "stylesheet" type = "text / css" href = "common_components.css" /> & Lt; Meta http-equiv = "content-type" content = "text / html; charset = UTF-8" /> & Lt; Link rel = "stylesheet" href = "slider.css" & gt; & Lt ;? Php include_once 'common_components.php'; $ Query = $ dbh- & gt; Queries ("SELECT movies_dir FROM settings"); $ Line = $ query- & gt; Obtain (PDO :: FETCH_ASSOC); Date_default_timezone_set ('UTC'); Echo "& lt; title & gt; movie scanner & lt; / title & gt;"; ? & Gt; & Lt; Script src = "jquery.min.js" & gt; &am
Read more