Both esProc and R language are typical data processing and analysis languages with two-dimensional structured data objects. They are all good at multi-step complex computations. However their two-dimensional structured data objects are quite different from each other in the underlying mechanism. As a result, esProc is ...
2014-09-26 313 0
Set operations are frequently used in statistical analysis with structured data, For example, listing all students who has published papers; listing all staff who has participated in all previous training; selecting qualified students in examination for re-examand so on. Within esProc, application of set is everywhere....
2014-09-25 280 0
In Java projects, sometimes accessing data in remote http server is required. The data can be ofxml format orjson format. The following will compare two accessing methods through an example.
Here is a servletwhich provides employee information query in json format. servlet accesses the employee table in the database an...
2014-09-24 274 0
If field (or combination of fields) k is table M’s primary key, and k, at the same time, exists in table B, then k is regarded as the foreign key of B. The foreign key maintains a relationship between two tables and is one of the most important concepts in structured data computing. Through object references, esProc ma...
2014-09-23 404 0
It is convenient to realize some common in-memory grouping with esProc, such as, equal grouping, alignment grouping and enumeration grouping. They are to be illustrated with the following examples.
Grouping basis of equal grouping is certain fields (or computed columns derived from fields) within a data ...
2014-09-22 302 0
esProc TSeq and SQL data table are all the structured 2-dimensional data objects. The records, indexes, and primary keys can all be applied to the structured data computing. Although both of them can be applied to the structured data computing, their application scenarios differ distinctly. TSeq is fit for solving the ...
2014-09-19 327 0
esProc can parallelly process big text files conveniently. The following case will illustrate its operating method.
Let’s assume that there is a text file, sales.txt, with ten million sales records. Its main fields include SellerID, OrderDate and Amount. Now compute each salesman’s total Amount of big orders in the pas...
2014-09-18 269 0
In esProc, the storage of cellset variables is ubiquitous. Cell values are convenient references during computation, but they could occupy too much memory. Data can be cleared from cells to reduce memory footprint after they accomplish their mission in computation. It should be particularly noted that, when the interme...
2014-09-17 280 0
1. Merge in proper order
Many a time, data could be stored in several data tables, for example, product sales records of several categories, and employee profiles of each department. In this case, we need to merge the data from multiple data tables for combined use. For the several normal homogeneous TSeqs, you can use...
2014-09-16 359 0
It is often required to sort records of tables during data analysis and computing. In esProc, sort function is used to sort data of sequences or table sequences. External memory sorting is required when data being sorted are massive and cannot be loaded into memory all together, for the ordinary sorting cannot handle t...
2014-09-15 256 0
In esProc, strings are not merely a data type; they can also be used as macros or string constants to construct expressions, or employed by eval() function to generate expressions dynamically as needed.
Macros in esProc refer to strings for composing expressions,only that these strings are usually generated dy...
2014-09-12 273 0
In an esProc table sequence, a field or certain fields can be designated as the prime key(s). In this case, some special functions can be employed to make query based on the prime key(s). This can both simplify the code and increase computational performance effectively.
1. find and pfind
Prime keys are common in datab...
2014-09-10 285 0
After data are imported from a data table, they are usually grouped as required and grouping and summarizing result is needed to be worked out. In esProc, groups function is used to compute the result of data grouping and summarizing; or the function will first group the data, then further analysis and computation are ...
2014-09-09 252 0
Here, we use esProc to analyze stock bullish trend. There is a variety of specific algorithms, from which, one will be illustrated the whole process in detail. Other cases can be solved in the similar codes. Specific requirements are:
Among the stocks which have kept going up for N days, what is the proportion of those...
2014-09-05 281 0
Program development in Java involves cross-database relational operations. The following example will illustrate Java’s method of handling these operations. sales table is in db2 database, employee table is in mysqldatabase. The task is to joinsales withemployee through sellerid of sales table and eid of employee table...
2014-09-04 769 0