Excel does provide a function for calculating new values within a pivot table. One example is extending a pivot table containing pricing and quantity data to compute an average selling price. For example, given the table below:

a new label called “ASP”, which is the Net Booking divided by the Quantity, can be added quickly and easily with Excel’s Calculated Field capability.

This feature is handy for adding labels on the fly that require a simple calculation.

In other cases, deriving the new field may not be so simple, yet needs to be performed each time the spreadsheet is updated. Python can programmatically add new data fields to the source table so that the data is ready for viewing whenever the pivot table is opened.

The script developed last time automated the data cleanup and pivot table generation tasks. Doing some further analysis based on the output spreadsheet, I created a chart of the Top 10 Customers for ABCD Catering:

Note that some of the company names are 15 characters or longer in length and occupy much of the chart space. It would be nice to have a shorter “nickname” for each company that could be used in the charts. One solution is to cut and paste the pivot table data, then modify the Company Name information by hand. Unfortunately, this would be very tedious. Another approach is to automate the process in the script and create a new column derived from a comprehensive reference table of company names and nicknames. The downside is that maintaining the list could be an issue as the business grows and the list of customers grows longer. A third method is to create an algorithm that uses the first word in the company name wherever possible, and uses a defined nickname for other special cases. “Sun Microsystems” becomes “Sun” and “Cisco Systems” becomes “Cisco”, while other company names such as “Hewlett-Packard” could be listed in a lookup with a nickname such as “HP”. The snippet below shows how this is done.

logolookup = {'Applied Materials':'AMAT', 'Electronic Arts':'EA',
              'Hewlett-Packard':'HP', 'KLA-Tencor':'KLA'}
if ("Company Name" in newdata[0]):
    cindx = newdata[0].index("Company Name")
    newdata[0][cindx+1:cindx+1] = ["Logo Name"]
    for rcnt in range(1,len(newdata)):
        if newdata[rcnt][cindx] in logolookup:
            newdata[rcnt][cindx+1:cindx+1] = [logolookup[newdata[rcnt][cindx]]]
        else:
            newname = newdata[rcnt][cindx].split()[0]
            newdata[rcnt][cindx+1:cindx+1] = [newname]
            logolookup[newdata[rcnt][cindx]] = newname

This code begins with a simple lookup for company names and can be easily extended as special case company names are added. Next, the column location of the “Company Name” field is identified and the new header “Logo Name” is inserted after “Company Name” in the list using the list[index:index] construct. The for loop iterates over each row in the table, checking whether the company name for that row exists in the logolookup dictionary, then inserting the abbreviated name. If not found, then the original company name is split() into words and the first word used as the new abbreviated name. Finally, the logolookup dictionary is updated with the new abbreviated name.

After running the program, the new column “Logo Name” has been inserted after “Company Name” and contains the shortened company names.

The new “Logo Name” column can be used in the previous pivot table and chart, replacing the “Company Name” field and producing a cleaner chart with less area used for displaying company name information.

Another use of this technique is to add a label for “Food Category” based on the type of food purchased. For example, the food items sold by ABCD Catering are: Caesar Salad, Cheese Pizza, Cheeseburger, Chocolate Sundae, Churro, Hamburger, Hot Dog, Pepperoni Pizza, Potato Chips and Soda. Let’s say that your manager wants to track the sales of different food categories, such as Burger, Dessert, HotDog, Drink, Pizza, Salad and Snack. Using the same technique outlined above, this code will add a column for Food Category with the appropriate entry for each food item:

foodlookup = {'Caesar Salad':'Salad', 'Cheese Pizza':'Pizza',
              'Cheeseburger':'Burger', 'Chocolate Sundae':'Dessert',
              'Churro':'Snack', 'Hamburger':'Burger', 'Hot Dog':'HotDog',
              'Pepperoni Pizza':'Pizza', 'Potato Chips':'Snack',
              'Soda':'Drink'}
if ("Food Name" in newdata[0]):
    cindx = newdata[0].index("Food Name")
    newdata[0][cindx+1:cindx+1] = ["Food Category"]
    for rcnt in range(1,len(newdata)):
        if newdata[rcnt][cindx] in foodlookup:
            newdata[rcnt][cindx+1:cindx+1] = [foodlookup[newdata[rcnt][cindx]]]
        else:
            newdata[rcnt][cindx+1:cindx+1] = ['UNDEFINED']

If a food item is not found in the lookup, the category is labeled UNDEFINED. This is an indication that there is a problem with the script and the lookup for food categories needs to be extended.

The section of the script which creates the pivot tables can be easily extended to build a new table based on the newly created label “Food Category”:

# What food category had the highest unit sales in Q4?
ptname = addpivot(wb,src,
         title="Unit Sales by Food Category",
         filters=("Fiscal Quarter",),
         columns=(),
         rows=("Food Category",),
         sumvalue="Sum of Quantity",
         sortfield=("Food Category",win32c.xlDescending))
wb.Sheets("Unit Sales by Food Category").PivotTables(ptname).PivotFields("Fiscal Quarter").CurrentPage = "2009-Q4"

Based on the output spreadsheet, the best selling food category in Q4 based on quantity is “Snack”, with sales of 13700 units.

Here is the completed script, also available on GitHub

#
# erppivotextended.py:
# Load raw EPR data, clean up header info,
# insert additional data fields and build 5 pivot tables
#
import win32com.client as win32
win32c = win32.constants
import sys
import itertools
tablecount = itertools.count(1)

def addpivot(wb,sourcedata,title,filters=(),columns=(),
             rows=(),sumvalue=(),sortfield=""):
    """Build a pivot table using the provided source location data
    and specified fields
    """
    newsheet = wb.Sheets.Add()
    newsheet.Cells(1,1).Value = title
    newsheet.Cells(1,1).Font.Size = 16

    # Build the Pivot Table
    tname = "PivotTable%d"%tablecount.next()

    pc = wb.PivotCaches().Add(SourceType=win32c.xlDatabase,
                                 SourceData=sourcedata)
    pt = pc.CreatePivotTable(TableDestination="%s!R4C1"%newsheet.Name,
                             TableName=tname,
                             DefaultVersion=win32c.xlPivotTableVersion10)
    wb.Sheets(newsheet.Name).Select()
    wb.Sheets(newsheet.Name).Cells(3,1).Select()
    for fieldlist,fieldc in ((filters,win32c.xlPageField),
                            (columns,win32c.xlColumnField),
                            (rows,win32c.xlRowField)):
        for i,val in enumerate(fieldlist):
            wb.ActiveSheet.PivotTables(tname).PivotFields(val).Orientation = fieldc
            wb.ActiveSheet.PivotTables(tname).PivotFields(val).Position = i+1

    wb.ActiveSheet.PivotTables(tname).AddDataField(
        wb.ActiveSheet.PivotTables(tname).PivotFields(sumvalue[7:]),
        sumvalue,
        win32c.xlSum)
    if len(sortfield) != 0:
        wb.ActiveSheet.PivotTables(tname).PivotFields(sortfield[0]).AutoSort(sortfield[1], sumvalue)
    newsheet.Name = title

    # Uncomment the next command to limit output file size, but make sure
    # to click Refresh Data on the PivotTable toolbar to update the table
    # newsheet.PivotTables(tname).SaveData = False

    return tname

def runexcel():
    """Open the spreadsheet ABCDCatering.xls, clean it up,
    and add pivot tables
    """
    excel = win32.gencache.EnsureDispatch('Excel.Application')
    #excel.Visible = True
    try:
        wb = excel.Workbooks.Open('ABCDCatering.xls')
    except:
        print "Failed to open spreadsheet ABCDCatering.xls"
        sys.exit(1)
    ws = wb.Sheets('Sheet1')
    xldata = ws.UsedRange.Value
    newdata = []
    for row in xldata:
        if len(row) == 13 and row[-1] is not None:
            newdata.append(list(row))
    lasthdr = "Col A"
    for i,field in enumerate(newdata[0]):
        if field is None:
            newdata[0][i] = lasthdr + " Name"
        else:
            lasthdr = newdata[0][i]

    logolookup = {'Applied Materials':'AMAT', 'Electronic Arts':'EA',
                  'Hewlett-Packard':'HP', 'KLA-Tencor':'KLA'}
    if ("Company Name" in newdata[0]):
        cindx = newdata[0].index("Company Name")
        newdata[0][cindx+1:cindx+1] = ["Logo Name"]
        for rcnt in range(1,len(newdata)):
            if newdata[rcnt][cindx] in logolookup:
                newdata[rcnt][cindx+1:cindx+1] = [logolookup[newdata[rcnt][cindx]]]
            else:
                newname = newdata[rcnt][cindx].split()[0]
                newdata[rcnt][cindx+1:cindx+1] = [newname]
                logolookup[newdata[rcnt][cindx]] = newname

    foodlookup = {'Caesar Salad':'Salad', 'Cheese Pizza':'Pizza',
                  'Cheeseburger':'Burger', 'Chocolate Sundae':'Dessert',
                  'Churro':'Snack', 'Hamburger':'Burger', 'Hot Dog':'HotDog',
                  'Pepperoni Pizza':'Pizza', 'Potato Chips':'Snack',
                  'Soda':'Drink'}
    if ("Food Name" in newdata[0]):
        cindx = newdata[0].index("Food Name")
        newdata[0][cindx+1:cindx+1] = ["Food Category"]
        for rcnt in range(1,len(newdata)):
            if newdata[rcnt][cindx] in foodlookup:
                newdata[rcnt][cindx+1:cindx+1] = [foodlookup[newdata[rcnt][cindx]]]
            else:
                newdata[rcnt][cindx+1:cindx+1] = ['UNDEFINED']

    rowcnt = len(newdata)
    colcnt = len(newdata[0])
    wsnew = wb.Sheets.Add()
    wsnew.Range(wsnew.Cells(1,1),wsnew.Cells(rowcnt,colcnt)).Value = newdata
    wsnew.Columns.AutoFit()

    src = "%s!R1C1:R%dC%d"%(wsnew.Name,rowcnt,colcnt)

    # What were the total sales in each of the last four quarters?
    addpivot(wb,src,
             title="Sales by Quarter",
             filters=(),
             columns=(),
             rows=("Fiscal Quarter",),
             sumvalue="Sum of Net Booking",
             sortfield=())

    # What are the sales for each food item in each quarter?
    addpivot(wb,src,
             title="Sales by Food Item",
             filters=(),
             columns=("Food Name",),
             rows=("Fiscal Quarter",),
             sumvalue="Sum of Net Booking",
             sortfield=())

    # Who were the top 10 customers for ABCD Catering in 2009?
    addpivot(wb,src,
             title="Top 10 Customers",
             filters=(),
             columns=(),
             rows=("Company Name",),
             sumvalue="Sum of Net Booking",
             sortfield=("Company Name",win32c.xlDescending))

    # Who was the highest producing sales rep for the year?
    addpivot(wb,src,
             title="Top Sales Reps",
             filters=(),
             columns=(),
             rows=("Sales Rep Name","Company Name"),
             sumvalue="Sum of Net Booking",
             sortfield=("Sales Rep Name",win32c.xlDescending))

    # What food item had the highest unit sales in Q4?
    ptname = addpivot(wb,src,
             title="Unit Sales by Food",
             filters=("Fiscal Quarter",),
             columns=(),
             rows=("Food Name",),
             sumvalue="Sum of Quantity",
             sortfield=("Food Name",win32c.xlDescending))
    wb.Sheets("Unit Sales by Food").PivotTables(ptname).PivotFields("Fiscal Quarter").CurrentPage = "2009-Q4"

    # What food category had the highest unit sales in Q4?
    ptname = addpivot(wb,src,
             title="Unit Sales by Food Category",
             filters=("Fiscal Quarter",),
             columns=(),
             rows=("Food Category",),
             sumvalue="Sum of Quantity",
             sortfield=("Food Category",win32c.xlDescending))
    wb.Sheets("Unit Sales by Food Category").PivotTables(ptname).PivotFields("Fiscal Quarter").CurrentPage = "2009-Q4"

    if int(float(excel.Version)) >= 12:
        wb.SaveAs('newABCDCatering.xlsx',win32c.xlOpenXMLWorkbook)
    else:
        wb.SaveAs('newABCDCatering.xls')
    excel.Application.Quit()

if __name__ == "__main__":
    runexcel()

Prerequisites
Python (refer to http://www.python.org)

Win32 Python module (refer to http://sourceforge.net/projects/pywin32)

Microsoft Excel (refer to http://office.microsoft.com/excel)

Source Files and Scripts
Source for the program erppivotextended.py and spreadsheet file ABCDCatering.xls are available at
http://github.com/pythonexcels/examples

Thanks — Dan

The goal of this exercise is to automate the generation of pivot tables from the last post, and save them to a new Excel file.

I started with the file newABCDCatering.xls from the previous post and record the macro to create this simple pivot table showing Net Bookings by Sales Rep and Food Name for the last four quarters.

Captured in Excel 2007, the recorded macro looks like this:

Sub Macro1()
'
' Macro1 Macro
'

'
    Selection.CurrentRegion.Select
    Sheets.Add
    ActiveWorkbook.PivotCaches.Create(SourceType:=xlDatabase, SourceData:= _
        "Sheet2!R1C1:R791C13", Version:=xlPivotTableVersion10).CreatePivotTable _
        TableDestination:="Sheet3!R3C1", TableName:="PivotTable1", DefaultVersion _
        :=xlPivotTableVersion10
    Sheets("Sheet3").Select
    Cells(3, 1).Select
    With ActiveSheet.PivotTables("PivotTable1").PivotFields("Fiscal Year")
        .Orientation = xlPageField
        .Position = 1
    End With
    With ActiveSheet.PivotTables("PivotTable1").PivotFields("Fiscal Quarter")
        .Orientation = xlColumnField
        .Position = 1
    End With
    With ActiveSheet.PivotTables("PivotTable1").PivotFields("Sales Rep Name")
        .Orientation = xlRowField
        .Position = 1
    End With
    With ActiveSheet.PivotTables("PivotTable1").PivotFields("Food Name")
        .Orientation = xlRowField
        .Position = 2
    End With
    ActiveSheet.PivotTables("PivotTable1").AddDataField ActiveSheet.PivotTables( _
        "PivotTable1").PivotFields("Net Booking"), "Sum of Net Booking", xlSum
End Sub

The post Mapping Excel VB Macros to Python covered a technique for recording a Visual Basic macro and porting it to Python. Using that approach, you could simply turn on the macro recorder and generate all the required tables, producing a long script with lots of redundancy. A better approach is to build a general purpose function that can be used over and over to generate the pivot tables.

Looking at the macro, you see lines specifying the Orientation of the field name, such as .Orientation = xlRowField and .Orientation = xlColumnField. A pivot table has four basic areas for fields:

• Report Filter (.Orientation = xlPageField)
• Column area (.Orientation = xlColumnField)
• Row area (.Orientation = xlRowField)
• Values area (PivotTables().AddDataField())

Each of these supports multiple fields (column fields for Sales Rep Name and Food Name were added in the example). The ordering of the fields changes the appearance of the table.

A general pattern should be apparent in this macro. First, the pivot table is created with the ActiveWorkbook.PivotCaches.Create() statement. Next, the columns and rows are configured with a series of ActiveSheet.PivotTables("PivotTable1").PivotFields() statements. Finally, the field used in the Values section of the table is configured using the ActiveSheet.PivotTables("PivotTable1").AddDataField statement. The general purpose function will need to contain all of these constructs. Note the parts that can’t be hard-coded: the source of the data, "Sheet2!R1C1:R791C13", and destination for the table, "Sheet3!R3C1" need to be determined based on the characteristics of the source data and can’t be hard coded in the general solution.

In Python, this pattern can be reduced to the following loop that covers fields for the Report Filter, Columns and Rows:

def addpivot(wb,sourcedata,title,filters=(),columns=(),
             rows=(),sumvalue=(),sortfield=""):
    """Build a pivot table using the provided source location data
    and specified fields
    """
    ...
    for fieldlist,fieldc in ((filters,win32c.xlPageField),
                            (columns,win32c.xlColumnField),
                            (rows,win32c.xlRowField)):
        for i,val in enumerate(fieldlist):
            wb.ActiveSheet.PivotTables(tname).PivotFields(val).Orientation = fieldc
        wb.ActiveSheet.PivotTables(tname).PivotFields(val).Position = i+1
    ...

Processing the Values field is more or less copied from the Visual Basic. To keep things simple in this example, this code is limited to adding “Sum of” values only, and doesn’t handle other Summarize Value functions such as Count, Min, Max, etc.

    wb.ActiveSheet.PivotTables(tname).AddDataField(
        wb.ActiveSheet.PivotTables(tname).PivotFields(sumvalue[7:]),
        sumvalue,
        win32c.xlSum)

The actual values for filters,columns and rows in the function are defined in the call to the function. The complete function creates a new sheet within the workbook, then adds an empty pivot table to the sheet and builds the table using the field information provided. For example, to answer the question: What were the total sales in each of the last four quarters?, the pivot table is built with the following call to the addpivot function:

# What were the total sales in each of the last four quarters?
addpivot(wb,src,
         title="Sales by Quarter",
         filters=(),
         columns=(),
         rows=("Fiscal Quarter",),
         sumvalue="Sum of Net Booking",
         sortfield=())

which defines a pivot table using the row header “Fiscal Quarter” and data value “Sum of Net Booking”. The title “Sales by Quarter” is used to name the sheet itself.

To make the output spreadsheet more understandable, the title parameter passed into the function and used as a title in each worksheet and as the tab name.

The complete script is shown below. Caveats:

• This script has been modified to run on both Excel 2007 and Excel 2003 and has been tested on those versions.
• Adding pivot tables increases the size of the output Excel file, which can be mitigated by disabling caching of pivot table data. Line 48 of the script contains the command newsheet.PivotTables(tname).SaveData = False, which has been commented out. Uncommenting this command will reduce the size of the output Excel file, but will require that the pivot table be refreshed before use by clicking on Refresh Data on the PivotTable toolbar.

#
# erpdatapivot.py:
# Load raw EPR data, clean up header info and
# build 5 pivot tables
#
import win32com.client as win32
win32c = win32.constants
import sys
import itertools
tablecount = itertools.count(1)

def addpivot(wb,sourcedata,title,filters=(),columns=(),
             rows=(),sumvalue=(),sortfield=""):
    """Build a pivot table using the provided source location data
    and specified fields
    """
    newsheet = wb.Sheets.Add()
    newsheet.Cells(1,1).Value = title
    newsheet.Cells(1,1).Font.Size = 16

    # Build the Pivot Table
    tname = "PivotTable%d"%tablecount.next()

    pc = wb.PivotCaches().Add(SourceType=win32c.xlDatabase,
                                 SourceData=sourcedata)
    pt = pc.CreatePivotTable(TableDestination="%s!R4C1"%newsheet.Name,
                             TableName=tname,
                             DefaultVersion=win32c.xlPivotTableVersion10)
    wb.Sheets(newsheet.Name).Select()
    wb.Sheets(newsheet.Name).Cells(3,1).Select()
    for fieldlist,fieldc in ((filters,win32c.xlPageField),
                            (columns,win32c.xlColumnField),
                            (rows,win32c.xlRowField)):
        for i,val in enumerate(fieldlist):
            wb.ActiveSheet.PivotTables(tname).PivotFields(val).Orientation = fieldc
            wb.ActiveSheet.PivotTables(tname).PivotFields(val).Position = i+1

    wb.ActiveSheet.PivotTables(tname).AddDataField(
        wb.ActiveSheet.PivotTables(tname).PivotFields(sumvalue[7:]),
        sumvalue,
        win32c.xlSum)
    if len(sortfield) != 0:
        wb.ActiveSheet.PivotTables(tname).PivotFields(sortfield[0]).AutoSort(sortfield[1], sumvalue)
    newsheet.Name = title

    # Uncomment the next command to limit output file size, but make sure
    # to click Refresh Data on the PivotTable toolbar to update the table
    # newsheet.PivotTables(tname).SaveData = False

    return tname

def runexcel():
    excel = win32.gencache.EnsureDispatch('Excel.Application')
    #excel.Visible = True
    try:
        wb = excel.Workbooks.Open('ABCDCatering.xls')
    except:
        print "Failed to open spreadsheet ABCDCatering.xls"
        sys.exit(1)
    ws = wb.Sheets('Sheet1')
    xldata = ws.UsedRange.Value
    newdata = []
    for row in xldata:
        if len(row) == 13 and row[-1] is not None:
            newdata.append(list(row))
    lasthdr = "Col A"
    for i,field in enumerate(newdata[0]):
        if field is None:
            newdata[0][i] = lasthdr + " Name"
        else:
            lasthdr = newdata[0][i]
    rowcnt = len(newdata)
    colcnt = len(newdata[0])
    wsnew = wb.Sheets.Add()
    wsnew.Range(wsnew.Cells(1,1),wsnew.Cells(rowcnt,colcnt)).Value = newdata
    wsnew.Columns.AutoFit()

    src = "%s!R1C1:R%dC%d"%(wsnew.Name,rowcnt,colcnt)

    # What were the total sales in each of the last four quarters?
    addpivot(wb,src,
             title="Sales by Quarter",
             filters=(),
             columns=(),
             rows=("Fiscal Quarter",),
             sumvalue="Sum of Net Booking",
             sortfield=())

    # What are the sales for each food item in each quarter?
    addpivot(wb,src,
             title="Sales by Food Item",
             filters=(),
             columns=("Food Name",),
             rows=("Fiscal Quarter",),
             sumvalue="Sum of Net Booking",
             sortfield=())

    # Who were the top 10 customers for ABCD Catering in 2009?
    addpivot(wb,src,
             title="Top 10 Customers",
             filters=(),
             columns=(),
             rows=("Company Name",),
             sumvalue="Sum of Net Booking",
             sortfield=("Company Name",win32c.xlDescending))

    # Who was the highest producing sales rep for the year?
    addpivot(wb,src,
             title="Top Sales Reps",
             filters=(),
             columns=(),
             rows=("Sales Rep Name","Company Name"),
             sumvalue="Sum of Net Booking",
             sortfield=("Sales Rep Name",win32c.xlDescending))

    # What food item had the highest unit sales in Q4?
    ptname = addpivot(wb,src,
             title="Unit Sales by Food",
             filters=("Fiscal Quarter",),
             columns=(),
             rows=("Food Name",),
             sumvalue="Sum of Quantity",
             sortfield=("Food Name",win32c.xlDescending))
    wb.Sheets("Unit Sales by Food").PivotTables(ptname).PivotFields("Fiscal Quarter").CurrentPage = "2009-Q4"

    if int(float(excel.Version)) >= 12:
        wb.SaveAs('newABCDCatering.xlsx',win32c.xlOpenXMLWorkbook)
    else:
        wb.SaveAs('newABCDCatering.xls')
    excel.Application.Quit()

if __name__ == "__main__":
    runexcel()

Prerequisites
Python (refer to http://www.python.org)

Microsoft Excel (refer to http://office.microsoft.com/excel)

Source Files and Scripts
Source for the program erpdatapivot.py and input spreadsheet file ABCDCatering.xls are available at
http://github.com/pythonexcels/examples

Thanks — Dan

But in my professional life, I’ve found few people who have a solid knowledge of pivot tables and are really comfortable using them in Excel. If you aren’t aware of pivot tables or haven’t had the time to try out this function in Excel, pivot tables provide a way to cross tabulate, sort, segregate and aggregate tabular data, enabling you to quickly summarize data and extract totals, averages, and other information from the source data. I first found out about pivot tables when I was working with our business unit financial analyst more than 10 years ago. She didn’t like our corporate ERP system (SAP) any more than I did, and found it much faster to dump the raw data into Excel and get the answers to her questions by using a pivot table. I’ve been a pivot table convert ever since.

Using the spreadsheet newABCDCatering.xls developed in the last post, let’s add a pivot table and answer the questions raised previously:

• What were the total sales in each of the last four quarters?
• What are the sales for each food item in each quarter?
• Who were the top 10 customers for ABCD Catering in 2009?
• Who was the highest producing sales rep for the year?
• What food item had the highest unit sales in Q4?

To build the pivot table, begin by selecting the entire data table in the Sheet2 worksheet by clicking cell A1, and typing the Control-* key combination (hold down Ctrl and press *). This selects the data in the table without also grabbing blank cells surrounding the table. This is effectively the same as selecting cell A1 and scrolling to the last column and row of data while holding down the left mouse key.

Next, if you’re using Excel 2007 or later, select the Insert tab then select PivotTable from the Pivot Table icon

Because you’ve selected the spreadsheet data, the dialog should already be populated with the range Sheet2!$A1:$M791 as shown below