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esProc Charts: The Sector Element

Used only in polar coordinates, the sector element is usually for plotting a pie chart. Here we’ll explain how it is employed and its properties. 1. Data properties Through the following pie chart for displaying vault results, we’ll discuss the basics of plotting the sector element.   A 1 =canvas() 2 =demo....

2015-06-01 931

esProc Solves Eight Queens Problem

Among lots of chess puzzles, the problem of the eight queens is the most well-known example. Eight queens must be placed on a 8×8 chessboard so that no queen attacks any others. Well, how many solutions are there?  A queen attacks any other queen that sits on the same row, column or diagonal. Thus a solution requi...

2015-05-29 891

esProc Charts: The Column Element

The column element is frequently used in plotting various charts. We’ve made some studies about it in esProc Charts: Coordinate Axes through examples. Here we’ll illustrate the setting of its properties and their roles. 1. Data properties The plotting algorithm below for plotting a clustered column chart of gym results...

2015-05-28 1217

An esProc Code Example of Computing Link-Relative Ratio and Year-on-year Comparison

A link-relative ratio is a percentage got by comparing the data of current period and that of the previous period. Usually the interval between the two periods is a month (sometimes an hour, a day, a week and a quarter). The link-relative ratio of April is computed by dividing, for example, its sales amount by that of ...

2015-05-28 909

Code Examples of esProc Foreign Key Function

If k (a single field or a combination of fields) is table M’s primary key, and k, at the same time, exists in table B, then k is regarded as B’s foreign key. The foreign key defines a relationship between two tables and is one of the most important concepts for structured data computing. Through object references, esPr...

2015-05-27 990

esProc Charts: The Line Element

We learned how to plot a dot chart element using logical coordinates in esProc Charts: The Dot Element. Here we’ll learn about plotting the line element. The line element is another one of the most basic chart elements, which is positioned by at least two pairs of logical coordinates. If there are more logical coordina...

2015-05-26 1221

Performance Test of esProc Script Execution

Sometimes we may encounter computations too complicated to be handled solely using library functions. We need to hardcode the computational logic using scripts. In that case the interpretative and executional performance of the script becomes really important. Not a few traditional database tasks, being unable to be ex...

2015-05-26 935

Importing Excel Data into Access with esProc

In daily work we have frequent use of text data or spreadsheets. We need to import data into database for further statistical analytics. For this task, esProc is a very handy tool. In the following example, we will import Excel data into an Access database, to demonstrate how to migrate text data into database with esP...

2015-05-25 3355

esProc Charts: The Axis Element

In esProc Charts: Coordinate Axes, we learned the basic usages of different coordinate axes and the setting of their properties. Once a logical axis is properly defined, the logical coordinates on it can be transformed into corresponding physical coordinates, according to which a certain chart element can be plotted. &...

2015-05-22 1200

Group MongoDB Collection and Find Top N members in esProc

Problem source：https://groups.google.com/forum/#!topic/mongodb-user/Rjv6lyUCe1s . Collection last3 has two fields: variable and timestamp. You need to first group documents by variable and find from each group the top 3 ones with the latest timestamp, and then find from the three documents the one with the earliest tim...

2015-05-22 1117

esProc Assists Java in Merging Text Files to Excel

Problem source：http://bbs.csdn.net/topics/390842850 .  In this case, you need to merge data from all text files in a given directory and export it to an Excel file. Each of these text files has tab-seperated data with one row and three columns.  JAVA approaches the problem by running a loop to retrieve a...

2015-05-21 1020

Find Differences between Text Files with esProc

Problem source：http://bbs.csdn.net/topics/360033579 .  Compare the following two text files of the same format and write the differences (different records) into a text file. Content of 1.txt： Proto      Local Address Foreign Address     State TCP 111.11.1.111:1975...

2015-05-20 1017

esProc Charts: The Dot Element

We talked about different types of coordinate axis used in esProc in esProc Charts: Coordinate Axes and learned that a chart element can be plotted on the coordinate plane after defining a pair of axes. From this article, we’ll discuss how to plot a chart according to specified position starting from the simplest dot e...

2015-05-20 1173

esProc Charts: Coordinate Axes

In esProc Charts: Coordinate Systems and Coordinate Transformation, we discussed the relation between logical axes and physical axes in plotting a chart with esProc, as well as how to position an axis and a chart element on the canvas. esProc provides a variety of logical axes for plotting different styles of charts. L...

2015-05-18 1165

Combine Text Files Conditionally with esProc

Problem source: http://bbs.csdn.net/topics/390507610 . There are multiple text files in a single directory which need to be combined according to specified conditions. The text files include, for example, 12345.txt, 12346.txt, 12347.txt, 2013070312345.txt, 2013070312346.txt, 2013070312347.txt and 2013070412347.txt...

2015-05-18 919