Creating R packagesPrevious:
What are the differences between R and S? This is analogous to the evaluation model in Scheme. This difference becomes manifest when free variables occur in a function.
Free variables are those which are neither formal parameters occurring in the argument list of the function nor local variables created by assigning to them in the body of the function. In S, the values of free variables are determined by a set of global variables similar to C, there is only local and global scope.
In R, they are determined by the environment in which the function was created. Consider the following function: For simplicity, we shall use both the cdf and pdf of the distribution as explicit arguments.
Example compiled from various postings by Luke Tierney. The code uses the fact that in S, functions are just lists of special mode with the function body as the last argument, and hence does not work in R one could make the idea work, though.
However, in R there is a much easier solution: Note that what you really need is the function closure, i.
With R scoping rules, this is a trivial problem; simply make up the function with the required definitions in the same environment and scoping takes care of it. With S, one solution is to add an extra parameter to the function and to the optimizer to pass in these extras, which however can only work if the optimizer supports this.
Nested lexically scoped functions allow using function closures and maintaining local state. A simple example taken from Abelson and Sussman is obtained by typing demo "scoping" at the R prompt. Nested lexically scoped functions also imply a further major difference.
Whereas S stores all objects as separate files in a directory somewhere usually. Data under the current directoryR does not. All objects in R are stored internally. When R is started up it grabs a piece of memory and uses it to store the objects. R performs its own memory management of this piece of memory, growing and shrinking its size as needed.
This difference also seems to make R faster than S. The down side is that if R crashes you will lose all the work for the current session.
In S this does not happen, because everything is saved in disk files and if you crash nothing is likely to happen to them. In fact, one might conjecture that the S developers felt that the price of changing their approach to persistent storage just to accommodate lexical scope was far too expensive.
Hence, when doing important work, you might consider saving often see How can I save my workspace? Other possibilities are logging your sessions, or have your R commands stored in text files which can be read in using source.
If you run R from within Emacs see R and Emacsyou can save the contents of the interaction buffer to a file and conveniently manipulate it using ess-transcript-mode, as well as save source copies of all functions and data used.
The glm family objects are implemented differently in R and S. The same functionality is available but the components have different names. Terms objects are stored differently. In S a terms object is an expression with attributes, in R it is a formula with attributes.Sarawak Add Maths Folio | Add Math Project Work Perak | Sample Add Maths Project (Selangor) | Complete Add Maths Project Work (Johor) Sample Answer | Contoh Jawapan Folio Matematik Tambahan Pulau Pinang | Sample Add Maths Project Work (Sabah) PMR and SPM Tips Do not miss a chance to get 10 per cent .
🔥Citing and more! Add citations directly into your paper, Check for unintentional plagiarism and check for writing mistakes.
date | timestamp.
A date or timestamp column or an expression that implicitly converts to a date or time stamp. If the date is the last day of the month, or if the resulting month is shorter, the function returns the last day of the month in the result.
Pay growth for women stops at this age Pay growth for college-educated women suddenly stops at around the age of 40, according to new findings from compensation research firm PayScale. 2. Fold over your sock most of the way, lengthwise, so that there is just a half inch not doubled over.
Cut horizontal cuts through the doubled over portion of sock, and slightly on to the non doubled over section, making sure to leave a portion uncut. On February 13, , the San Antonio Spurs found themselves in a surprisingly close game in Cleveland.
Late in the fourth quarter, Cavs rookie shooting guard Dion Waiters made the biggest basket of his young NBA career, knocking down a tough jumper to .