nandeshwar.info

Linked Table Query Returning Incorrect Results

a7n9 — Wed, 18 Aug 2010 19:24:47 +0000

We had this annoying problem: a simple query in Access to a linked table (using ODBC and MS SQL server) returned incorrect results, though the same query returned correct results in MS SQL server. By incorrect I mean the field values were different, so rather than returning AZ, the query returned BZ (some other value in that field).

We thought that it was a table size issue, may be the driver could not handle huge data. However, the problem was with the “unique record identifier” while linking the table, as JM reported here. I did not have this problem any longer when I did not select any fields for the unique record identifier while linking the table.

Microsoft query in Excel and Case statement

a7n9 — Thu, 15 Apr 2010 19:49:08 +0000

It is frustrating that I need to pull the data from SQL server using complex queries and then format it in Excel to ”prettify” the data. Thankfully, I can use the Microsoft query in Excel to get the data from SQL server and create a table or a PivotTable. Today, I encountered a problem with the case statement.

Although my syntax was right, MS Query kept throwing exception about the CASE statement. I read some discussions on-line, and some people had the wrong syntax, such as including the alias of the case statement in the group by statement. I did not have that problem. Finally, I found the solution: It was the order by clause. I was using the alias of the case statement in the order by clause. I removed it and the query ran just fine.

Mining publication data

a7n9 — Mon, 08 Mar 2010 15:57:24 +0000

I found treasure! Publication and citation data with metadata (author names, addresses, affiliation): http://citeseer.ist.psu.edu/oai.html

I was reading about knowledge management here, which says that knowledge management is nonsense. I agree to a certain degree, not because of the field, but because of its name. How do you manage knowledge? Isn’t knowledge derived? Wasn’t information “science” good enough? (I have problem with “business intelligence” as well…) As the author of that article says, it is a new term coined to attract attention. He does provide some evidence, but I was left unsatisfied.

I thought of performing text mining on publications database, and citeseer has this great resource. I downloaded the data (72 XML files), performed some clean-up, and ran a script to pull citeseer ID, author addresses, and publication dates where the abstract contained the term “knowledge management”. I was interested in seeing the trend of publication and places of publication.

Have a look at this chart:

There is a definite growth in this area, at least in research and publications. It is startling to see a paper published in 1970, and a peak in 2002. As citeseer data ends in 2004, it is possible that it doesn’t have complete publication history of 2004.

Geographic location wise, the US and Europe leads the way in number of publications:

My experiments with sparklines

a7n9 — Wed, 23 Sep 2009 18:05:19 +0000

For the uninitiated, Sparklines are “data-intense, design-simple, word-sized graphics” according to its inventor Edward Tufte. I always wanted to include them in my trend reports. The challenge: How and Which tool to use?

The data came from this report came from a complex query using SQL server and Access that had this format:

College	Major	2005	2006	2007	2008	2009
A	B	10	15	14	18	25

Some options I investigated and tried (be sure to read this page, you might find many more):

Google’s Chart API (http://code.google.com/apis/chart/types.html): you can embed these in Google spreadsheets, create HTML pages using Excel via VBA, or embed them in Excel sheets. Alas, none would work the way I would like them to work: In-cell graphics
Use Sparklines for Excel add-in: this add-in will create great in-cell charts (bar, bullet graphs, sparklines, etc), but copying them down is difficult and resource intensive, and any change you make in the column size will alter the shape of that chart. In addition, I had more than 400 rows to populate–these would be too many objects in a spreadsheet for Excel to handle. My machine froze when I tried to copy it for 10 rows.
Use R’s implementation by Jason Dieterle (search on this page for Jason Dieterle (email), January 28, 2008. Works very good. I modified the code to print max and mins only, but the function generates a graphic, which needed to be embeded in LaTex file. It did not work nicely. Charts were too big to fit in a cell of a table.
Create bar charts in Excel using REPT function. I tried different font sizes and styles, but it didn’t look pretty, for the range of data varied. (Hint: make the alignment of text 90, use pipe signs, create columns and graphs for each data value, remove gridlines, keep the columns very close. It almost worked.)
Use spark package for LaTex, doesn’t work in pdflatex, and you have to play a lot with the settings
Use sparklines package for LaTex. Problem was that data needed to be normalized (or scaled) from 0 to 1, and needed extra parameters for min and max points. Solution: create a normalize function in Excel, and write a big formula to produce the exact needed string for the sparklines to work i.e.:
\begin{sparkline}{5} \sparkdot 1 1 blue \sparkdot 0.2 0 red \spark 0.2 0 0.4 0.0625 0.6 0.5625 0.8 0.75 1 1 / \end{sparkline}

Here’s the normalize function:

Public Function Normalize(cell2Normalize As Range, WholeRng As Range)
       Normalize = (cell2Normalize.Value - WorksheetFunction.Min(WholeRng)) / (WorksheetFunction.Max(WholeRng) - WorksheetFunction.Min(WholeRng))
End Function

Here’s the big formula to convert the range for data values from 2005 to 2009 (in the range E2:I2) to the sparkline LaTex environment.
="\begin{sparkline}{5} " & "\sparkdot " & CHOOSE(MATCH(MAX(E2:I2),E2:I2,0),0.2,0.4,0.6,0.8,1) & " " & 1 & " blue " & "\sparkdot " & CHOOSE(MATCH(MIN(E2:I2),E2:I2,0),0.2,0.4,0.6,0.8,1) & " " & 0 & " red " & " \spark 0.2 " & Normalize(E2,E2:I2) & " 0.4 " & Normalize(F2,E2:I2) & " 0.6 " & Normalize(G2,E2:I2) & " 0.8 " & Normalize(H2,E2:I2) & " 1 " & Normalize(I2,E2:I2) & " / \end{sparkline}"

This last option worked beautifully. I dragged the formula down. I selected the data, and clicked on “Convert Table to LaTex” button (using this add-in). Copied the LaTex code to clipboard and pasted it in my LaTex editor. Manually merged the rows for colleges (using \multirow), and generated a beautiful looking pdf.

I was very happy. Printed it in color. Got a request back very soon that there should be total rows.

I forgot about the sparklines and created a report in Access with plain old numbers in less than 15 mins. Gave it back.

I tried to repeat this – Sparkline in Cognos -in Access with no luck.

(I later tried it one more time: Got the data in Excel using External data> Access, created a pivottable with rows and all, did some formatting, copied and pasted values and formats, inserted sparkline code, converted it to LaTex, copied and pasted in LaTex editor, and here’s the beautiful looking sample pdf of 16)

I wish there were simple reporting solutions that included awesome data visualization tools. (BTW, Excel 2010 will have sparklines: link) For this report, I did try Sweave, R, and LaTex, but because of the time constraints I could not investigate it further.

Please comment if you know any other way which meet (or don’t, Tableau is certainly one) these conditions: inexpensive (read free), efficient, and repeatable.

The search key was not found in any record in Access

a7n9 — Tue, 15 Sep 2009 20:07:58 +0000

Well, I got this error message today while I was trying to import a text file:

“The search key was not found in any record”

After some research, I found that either it was a bug caused by Microsoft Jet 4.0 Service Pack or it was the size of the database (should be not greater than 2GB). It turned out to be the later one. I fixed this problem by compacting and resizing the database. In Access 2007, you click on the Office Button (Top Left Corner), then Manage > Compact and Repair Database.

Auto Filter Cursor Movement

a7n9 — Mon, 01 Jun 2009 19:09:46 +0000

Don’t you hate it when you are working with many fields and you want to filter a particular field, so you apply auto filter on the all fields, but you find out that the field you were working on is gone from your sight and you see A1 cell. I did. Not anymore.

Solution: Simply hit the left or the right arrow key, and it will take you to the left or the right cell of the field you were working on.

Things they didn’t teach in school

a7n9 — Fri, 22 May 2009 19:10:50 +0000

My gripe about graduate school is that the school focused on well-established software and never embraced nor encouraged open-source software. If they had taught, or at least introduced, these following open-source software, it would have helped us immensely to produce the best looking reports with great data analysis. We, however, had to struggle with SAS/Excel to get the graphs and analysis needed, and then spend hours to perform formatting in Word. Why they didn’t teach us:

LaTex: a powerful typeset editor, where you focus on writing and not on formatting. It takes care of all the headings, page numbering, figure/table/equation numbering, TOC, bibliography/citation, and more. Although the learning curve is rather steep, once you get the hang of it, life becomes so easy. For windows: you need to get MikTex and any LaTex editor, such as LEd, LyX, or WinEd
R: awesome statistical package with wonderful graphics components. Producing stunning graphics and statistics has never been easy. It had me at summary. Any software that can do produce the following, just by giving summary(iris) command has to be great:

Summary produced by R of the iris data set

In my thesis, I had plenty of equations, and every time I made some significant changes, MS Word happily would turn those equations into empty white boxes — and then I had to rewrite them. In retrospect, I find it ridiculous that I was entering citations manually. So every time I added a new reference, I would manually change the bibliography page and the page where I cited that reference. With LaTex, it is just a breeze to do all this.

Descriptive stats, Box-plots, normal curves, neural network, charts with LaTex equations, and a lot of more stuff, all could be easily done using R, and the best part is “repeatability.” With simple commands, you could export all the charts as images for various data sets or for various training algorithms. No sweat! Try that with Excel. (I did some years ago).

Data-Information Visualization

a7n9 — Thu, 21 May 2009 12:34:56 +0000

Ever since I read the book The Visual Display of Quantitative Information, by Edward R. Tufte, I am captivated by the idea of creating good design while doing data analysis or dashboard building. Although Excel 2007 charts are much nicer than its previous births, I have started disliking Excel charts. I am even developing an eye for picking out the bad information pixels. Apart from Tufte’s books, these books have helped me immensely:

The Elements of Graphing Data, by William S. Cleveland
Information Dashboard Design, by Stephen Few

Administrators/executives neither have the time nor the patience to understand complicated data mining algorithms and its results, and when they don’t understand them most probably they will never go in “production.” Simple, yet informative, designs and charts have better chances of going in production, which I am sure every data miner longs for.

I found a course web-site on Information Visualization: http://www.stat.auckland.ac.nz/~ihaka/120/lectures.html

Access to the VB project is not trusted

a7n9 — Fri, 24 Apr 2009 14:42:37 +0000

I was trying to enable an add-in for Excel 2007, and I kept getting this error:

Access to the VB project is not trusted

You can turn this message off by going to Developer tab in the ribbon and then clicking on the Macro security button, and checking the check box for “Trust access to the VBA project object model.”

A word of caution: be wary of the add-ins/projects that need VBA access. Don’t allow any project/add-in with VBA access, unless you know its exact purpose or the author of that project.

nandeshwar.info

Linked Table Query Returning Incorrect Results

Microsoft query in Excel and Case statement

Mining publication data

My experiments with sparklines

The search key was not found in any record in Access

Tag Cloud of Data Mining Jobs

Auto Filter Cursor Movement

Things they didn’t teach in school

Data-Information Visualization

Access to the VB project is not trusted