Patent Grant
7146561
The present invention relates to the field of information processing by digital computers, and more particularly to a method and system, in an electronic spreadsheet, for comparing series of cells.
Before computers, numerical analyses, particularly financial ones, were usually prepared on an accountant's columnar pad or spreadsheet, with pencil and calculator in hand. By organising data into columns and rows, spreadsheets afford the rapid assimilation of information by a reader. The task of preparing a spreadsheet on paper, however, is not quite so fast. Instead, the process tends to be very slow, as each entry must be tediously calculated and entered into the spreadsheet. Since all calculations are the responsibility of the preparer, manually prepared spreadsheets are also prone to errors. Hence, preparation of spreadsheets by hand is slow, tedious, and unreliable.
With the advent of microcomputers, a solution was forthcoming in the form of “electronic spreadsheets.” Better known simply as “spreadsheets,” these software programs provide a computerised replacement for the traditional financial modelling tools: the accountant's columnar pad, pencil, and calculator. In some regards, spreadsheet programs are to those tools what word processors are to typewriters. Spreadsheets offer dramatic improvements in ease of creating, editing, and using financial models.
A typical spreadsheet program configures the memory of a computer to resemble the column/row or grid format of an accountant's columnar pad, thus providing a visible calculator for a user. Because this “pad” exists dynamically in the computer's memory, however, it differs from paper pads in several important ways. Locations in the electronic spreadsheet, for example, must be communicated to the computer in a format which it can understand. A common scheme for accomplishing this is to assign a number to each row in a spreadsheet, a letter to each column, and another letter to each sheet (or page) of the spreadsheet. To reference a location at column A and row 1 of the second page (i.e., the upper-left hand corner), for example, the user types in “B:A1”. In this manner, the spreadsheet defines an addressable storage location or “cell” at each intersection of a row with a column within a given page.
Data entry into an electronic spreadsheet occurs in much the same manner that information would be entered on an accountant's pad. After a screen cursor is positioned at a desired location, the user can enter alphanumeric information. Besides holding text and numeric information, however, spreadsheet cells can store special instructions or “formulas” specifying calculations to be performed on the numbers stored in spreadsheet cells. Such spreadsheet cells can also be defined and named as a range as long as they are arranged as a convex set of cells. A typical example of such a named range simply corresponds to a regular table found in an accountant's pad. In this fashion, range names can serve as variables in an equation, thereby allowing precise mathematical relationships to be defined between cells. The structure and operation of a spreadsheet program, including advanced functions such as functions and macros, are documented in the technical, trade, and patent literature. For an overview, see e.g., Cobb, S., Using Quattro Pro 2, Borland-OsbomeIMcGraw-Mll, 1990; and LeBlond, G. and Cobb, D., Using 1-2-3, Que corp., 1985. The disclosures of each of the foregoing are hereby incorporated by reference.
Electronic spreadsheets offer many advantages over their paper counterparts. For one, electronic spreadsheets are much larger (i.e., hold more information) than their paper counterparts; electronic spreadsheets having thousands or even millions of cells are not uncommon. Spreadsheet programs also allow users to perform “what-if” scenarios. After a set of computational relationships has been entered into a worksheet, thanks to imbedded formulas for instance, the spread of information can be recalculated using different sets of assumptions, with the results of each recalculation appearing almost instantaneously. Performing this operation manually, with paper and pencil, would require recalculating every relationship in the model with each change made. Thus, electronic spreadsheet systems were invented to solve “what-if” problems, that is, changing an input and seeing what happens to an output.
Conventional spreadsheets come today with some imbedded facilities allowing the spreadsheet user to develop his/her own tools addressing his/her own specific needs. The most popular facility of that kind is known as the “macro” language which corresponds to a programming language allowing to automate tasks that the user would instead perform manually. Such a language can be used advantageously when the manipulations performed within a spreadsheet correspond to repetitive steps which can be “packaged” within automated macros. Besides the gain in efficiency provided by such macros, the macros present also the advantage of reducing, if not eliminating, user errors during spreadsheet manipulations. Indeed as the successive steps of a given macro will be followed each time the macro is invoked, any correction applied to a problem found during the execution of the macro will be recorded in the macro, and thus reapplied later on for each new call of the macro. Besides the macro language itself, the macro facility often includes an integrated macro development environment aimed to facilitate the development of macros or the sharing of macros between different spreadsheets. Such environments are typically based on object oriented (OO) techniques which are today the de facto standard for software engineering.
When macros are developed in an electronic spreadsheet, one of the typical objects manipulated by the macro language corresponds to spreadsheet cells which can be arranged as ranges of cells, or more generally to what we call series of cells. A range of cells can be defined as a convex set of cells. A series of cells can be defined as a set of convex sets of cells. When objects such as series of cells are part of the logic of a macro, it is common to have to compare two different objects of this type. This type of comparison aims at determining if a first series of cells is either disjoined from, or equal to, or included in, or overlapping with, or including a second series of cells. The conventional techniques used to perform this type of comparison, such as the ones documented in the technical literture, rely on a geometrical representation of cells within an electronic spreadsheet. For instance a sheet within a electronic spreadsheet can be formally represent by a geometrical plan, with two coordinates. Any cell belonging to this sheet is associated with a row coordinate and with a column coordinate. With such a formal representation, the comparison of two ranges of cells (named “A” and “B”) within a given sheet can be performed with a macro of the following kind:
The above program is not very complex and relatively fast to execute (the longest path corresponding to 13 statements to execute), but it only performs the comparison of two ranges of cells in a two-dimensionnal spreadsheet. When ranges of cells must be compared in a three-dimensionnal spreadsheet (as it is the case for conventional electronic spreadsheets available on the market), then its complexity remains at the same level, but the execution time is increased. With multi-dimensionnal environments containing more than 3 dimensions, the execution time may become excessive.
If now series of cells have to be compared, then another level of complexity is introduced. Let illustrates it with a simple example in a two-dimensionnal spreadsheet: two series of cells named “A” and “B”, each constituted by two ranges of cells respectively named “A1”, “A2” and “B1”, “B2”, are compared to determine if the series of cells “A” is either disjoined from, or equal to, or included in, or overlapping with, or including the series of cells “B”. As “A1”, “A2”, “B1” and “B2” are ranges of cells, a natural thought process would be to first compare each of the ranges “A1” and “A2” with each of the ranges “B1” and “B2”, and then to perform some logic based on the results of the four range comparisons (“A1” vs “B1”, “A1” vs “B2”, “A2” vs “B1”, and “A2” vs “B2”). It turns out that this method cannot properly resolve some situations, as illustrated in
The present invention defines a system and a method for resolving the above mentioned problem in a way which first does not depend on the number of dimensions defined in the working environment, and which second does not depend on the structure of the objects to be compared. The present invention takes advantage of the inheritance properties available in object oriented environments.
The present invention relates to the field of information processing by digital computers, and more particularly to a method and system, in an electronic spreadsheet, for comparing two series of cells, a series of cells comprising one or a plurality of cell range, a cell range comprising one or a plurality of cells. The method of comparing two series of cells comprises the steps of:
The novel and inventive features believed characteristics of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative detailed embodiment when read in conjunction with the accompanying drawings, wherein:
System Hardware
As shown in
Illustrated in
Interface
A. Introduction
The following description will focus on the presently preferred embodiments of the present invention, which are embodied in spreadsheet applications operative in the Microsoft Win95 environment. The present invention, however, is not limited to any particular application or any particular environment. Instead, those skilled in the art will find that the system and methods of the present invention may be advantageously applied to a variety of system and application software, including database management systems, word processors, and the like. Moreover, the present invention may be embodied on a variety of different platforms, including Macintosh, UNIX, NextStep, and the like. Therefore, the description of the exemplary embodiments which follows is for purposes of illustration and not limitation.
Referring now to
Windowing interface 160 includes a screen cursor or pointer 185 for selecting and otherwise invoking screen objects of interest. In response to user movement signals from the pointing device 105, the cursor 185 floats (i.e., freely moves) across the screen 106 to a desired screen location. During or after cursor movement, the user may generate user-event signals (e.g., mouse button “clicks” and “drags”) for selecting and manipulating objects, as is known in the art. For example, Window 160 may be closed, re-sized, or scrolled by “clicking” (selecting) screen components 172, 174/5, and 177/8, respectively.
In a preferred embodiment, screen cursor 185 is controlled with a mouse device. Single-button, double-button, or triple-button mouse devices are available from a variety of vendors, including Apple Computer of Cupertino, Calif., Microsoft Corporation of Redmond, Wash., and Logitech Corporation of Fremont, Calif., respectively. More preferably, screen cursor control device 105 is a two-button mouse device, including both right and left “mouse buttons.”
Programming techniques and operations for mouse devices are well documented in the programming and hardware literature; see e.g., Microsoft Mouse Programmer's Reference, Microsoft Press, 1989. The general construction and operation of a GUI event-driven system, such as Windows, is also known in the art: see, e.g., Petzold, C., Programming Windows, Second Edition, Microsoft Press, 1990. The disclosures of each are hereby incorporated by reference.
B. Preferred Interface
Shown in
The toolbar 220, shown in further detail in
The notebook, which provides an interface for entering and displaying information of interest, includes a plurality of spreadsheet pages. Each page may include conventional windowing features and operations, such as moving, re-sizing, and deleting. In a preferred embodiment, the notebook includes 256 spreadsheet pages, all of which are saved as a single disk file on the mass storage 107. Workspace 200 may display one or more notebooks, each sized and positioned (e.g., tiled, overlapping, and the like) according to user-specified constraints.
Each spreadsheet page of a notebook includes a 2-D spread. Page A from the notebook 200, for example, includes a grid in row and column format, such as row 3 and column F. At each row/column intersection, a box or cell (e.g., cell C4) is provided for entering, processing, and displaying information in a conventional manner. Each cell is addressable, with a selector being provided for indicating a currently active one (i.e., the cell that is currently selected).
As shown in
In addition to aiding in the selection of an appropriate page of information, the user-customizable page identifiers serve aid in the entry of spreadsheet named range addresses. For example, when entering a formula referring to a named range of cells on another page, the user may simply use the descriptive page name in the named range address, thus making it easier for the user to understand the relationship of the cell(s) or information being referenced.
A general description of the features and operation of the spreadsheet notebook interface may be found in Quattro Pro for Windows (Getting Started, User's Guide and Building Spreadsheet Applications), available from Borland International.
Comparison of Series of Cells
A. Introduction
As the power of spreadsheet environments has increased since several years, it is today possible to develop complex custom applications solely based on spreadsheets, as opposed to applications developed with general purpose programming languages like C++ or VisualBasic from Microsoft Corporation. This can be achieved thanks to the spreadsheet imbedded tools such as macro languages.
Within macros developed thanks to macro language, it is common to have to evaluate how two sets of cells compare together. Such sets of cells are called “series of cells” and are not constrained by any structural rule. When two such series of cells have to be compared, the objective is to determine if the first series of cells (referred to as the series “ASerie”):
As previously outlined, conventional techniques based on a “geometrical” comparison of series of cells ask for an excessive complexity resulting both into poor performances and in a lack of flexibility with respect to the characteristics (such as the number of dimensions) of the environment to which the series of cells belong.
The present invention offer a user-friendly solution to this problem by defining a method and a system for comparing series of cells.
In the following, the above-mentioned series of cells will correspond to any set of cells, whether they are or not connex or convex.
B. Series Comparator
In contrast to just-described conventional techniques, the present invention provides a more powerful, efficient and generic method for comparing series of cells in the form of a “Series Comparator”. The comparator allows an electronic spreadsheet user to easily and efficiency evaluate how two series of cells compare together.
In a preferred embodiment, the present invention is used in three steps:
The decision to compare two series of cells belongs to the spreadsheet application user. A single repository, called “Comparison Table”, is used to record some key intermediary information during the process of series of cells comparison. This Comparison Table is preferably saved on a main memory 102, but could also be saved on a non volatile memory (typically but not necessary as part of the spreadsheet disk file on the mass storage 107).
Referring now to
The method for comparing series of cells to take advantage of the present invention is summarised in flowchart 600 of
The step 515 of determining how the both series of cells ASerie and BSerie mutually compare, can be summarized in an alternate embodiment as follows. The output of the comparison is derived from a decision table taking the following form.
Alternate Embodiments
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood that various changes in form and detail may be made therein without departing from the spirit, and scope of the invention.
The Series Comparator method and system according to the present invention may be used advantageously in those environments where elements of information are organised as multidimensional tables having more than three dimensions.
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