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Posts Tagged ‘VBA’

My experiments with sparklines

September 23rd, 2009 4 comments

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.

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Categories: Uncategorized Tags: , , , , , , , ,

Access to the VB project is not trusted

April 24th, 2009 2 comments

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.

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Categories: Error messages Tags: , ,

Student’s t-test for equal means

October 29th, 2008 No comments

If you do not wish to enter complex formula in Excel and you already have calculated average, count, and variance for your samples(Tip:use a PivotTable), then you can use these user-defined functions to calculate the t-test stat value and degrees of freedom required to do hypothesis testing. Both the functions provide an optional argument for the assumption of equal variances; by default it is set to false.

Here’s the code for t-test:
‘—————————————————————————————
‘ Procedure : TTESTM
‘ DateTime  : 10/29/2008 08:35
‘ Author    :
‘ Purpose   : To get the t-stat value when comparing two means with an optional input
‘               for equal or unequal variances
‘               by default the function assumes that the user is comparing means with unequal variances
‘—————————————————————————————
‘
Public Function TTESTM(davg1 As Double, dcnt1 As Double, dvar1 As Double, davg2 As Double, dcnt2 As Double, dvar2 As Double, Optional blnEqVar As Boolean = False) As Double

On Error GoTo TTESTM_Error
    Dim dResult As Double, dNumer As Double, dDenon As Double, dPooledVar As Double

dNumer = davg1 – davg2

‘if equal variances are not assumed
‘http://www.itl.nist.gov/div898/handbook/eda/section3/eda353.htm
If Not blnEqVar Then
    dDenon = Sqr((dvar1 ^ 2 / dcnt1) + (dvar2 ^ 2 / dcnt2))
Else
‘if equal variances are assumed, then calculated the pooled variance
    dPooledVar = Sqr((((dcnt1 – 1) * dvar1 ^ 2) + ((dcnt2 – 1) * dvar2 ^ 2)) / (dcnt1 + dcnt2 – 2))
    dDenon = dPooledVar * Sqr((1 / dcnt1) + (1 / dcnt2))
End If

dResult = dNumer / dDenon

TTESTM = dResult
    Exit Function

TTESTM_Error:
    TTESTM = Null

End Function

Here’s the code for the degrees of freedom:
‘—————————————————————————————
‘ Procedure : DOFTTESTM
‘ DateTime  : 10/29/2008 08:50
‘ Author    :
‘ Purpose   : To get the degrees of freedom for the t-test when comparing two means with an optional input
‘               for equal or unequal variances
‘               by default the function assumes that the user is comparing means with unequal variances
‘—————————————————————————————
‘
Public Function DOFTTESTM(dcnt1 As Double, dvar1 As Double, dcnt2 As Double, dvar2 As Double, Optional blnEqVar As Boolean = False) As Double

    Dim dResult As Double, dNumer As Double, dDenon As Double

On Error GoTo DOFTTESTM_Error
‘if equal variances are not assumed, then use a complicated formula to compute degrees of freedom
‘http://www.itl.nist.gov/div898/handbook/eda/section3/eda353.htm
    If Not blnEqVar Then
        dNumer = ((dvar1 ^ 2 / dcnt1) + (dvar2 ^ 2 / dcnt2)) ^ 2
        dDenon = ((dvar1 ^ 2 / dcnt1) ^ 2 / (dcnt1 – 1)) + ((dvar2 ^ 2 / dcnt2) ^ 2 / (dcnt2 – 1))
        dResult = dNumer / dDenon
    Else
        dResult = dcnt1 + dcnt2 – 2
    End If
    
DOFTTESTM = dResult

    Exit Function

DOFTTESTM_Error:
    DOFTTESTM = Null

End Function

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Categories: String Operations, Uncategorized, Useful Procedures Tags: , ,

Convert Text to Uppercase

September 17th, 2007 2 comments

If you want to convert the text to uppercase, use the following code; however, I recommend downloading ASAP Utilities, it has many functionalities, including text conversion. It doesn’t offer source code though.

Here’s my code for uppercase conversion:
(If you want to convert your text to lowercase, replace Ucase with Lcase function in the code)

‘Will convert selected range to Upper case, using array
Sub Conv2UCase()
On Error GoTo Conv2UCase_Error

Dim vDataArr As Variant
Dim lUpperBndRow As Long, lUpperBndCol As Long
Dim lRow As Long, lCol As Long

’store selected values in an array
vDataArr = Selection
‘get the upper bound of rows
lUpperBndRow = UBound(vDataArr, 1)
‘get the upper bound of cols
lUpperBndCol = UBound(vDataArr, 2)

‘Start a loop to go through all the elements of the array
For lRow = 1 To lUpperBndRow
    For lCol = 1 To lUpperBndCol
        ‘Check if the value is text, if not don’t convert
        If WorksheetFunction.IsText(vDataArr(lRow, lCol)) Then
            ‘Convert values to upper case
            vDataArr(lRow, lCol) = UCase(vDataArr(lRow, lCol))
        End If
    Next lCol
Next lRow
‘Return the converted values to the range
Selection = vDataArr
Exit Sub

Conv2UCase_Error:
    MsgBox “Error ” & Err.Number & ” (” & Err.Description & “) in Sub:Conv2UCase”
End Sub

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Categories: String Operations, Uncategorized, Useful Procedures Tags: , ,

A function to reverse a string

August 16th, 2007 1 comment

Very simple, uses the VBA function StrReverse to reverse the input string.

‘A function to reverse a string provided as input
‘For example, the string “abcd” will become “dcba”
‘Uses the VBA function StrReverse
Public Function ReverseString(sInputString As String) As String
On Error GoTo ReverseString_Error
    
ReverseString = StrReverse(sInputString)
    Exit Function

ReverseString_Error:
    ReverseString = “#ERROR#”
End Function

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