Excel Gurus Gone Wild: Do the IMPOSSIBLE with Microsoft Excel

Excel Gurus Gone Wild: Do the IMPOSSIBLE with Microsoft Excel

by Bill Jelen
     
 

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Drawn from actual excel conundrums posted on the author's website, mrexcel.com, this high-level resource is designed for people who want to stretch Excel to its limits. Tips for solving 100 incredibly difficult problems are covered in depth and include extracting the first letter of each word in a paragraph, validating URL's, generating random numbers without

Overview

Drawn from actual excel conundrums posted on the author's website, mrexcel.com, this high-level resource is designed for people who want to stretch Excel to its limits. Tips for solving 100 incredibly difficult problems are covered in depth and include extracting the first letter of each word in a paragraph, validating URL's, generating random numbers without repeating, and hiding rows if cells are empty. The answers to these and other questions have produced results that have even surprised the Excel development team.

Product Details

ISBN-13:
9781615474011
Publisher:
Holy Macro! Books
Publication date:
04/01/2009
Sold by:
Barnes & Noble
Format:
NOOK Book
Pages:
224
Sales rank:
996,409
File size:
8 MB

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Read an Excerpt

Excel Gurus Gone Wild


By Bill Jelen, Kitty Wilson

Holy Macro! Books

Copyright © 2009 Bill Jelen
All rights reserved.
ISBN: 978-1-932802-50-4



CHAPTER 1

Find the First Non-Blank Value in a Row


Challenge: You want to build a formula to return the first non-blank cell in a row. Perhaps columns B:K reflect data at various points in time. Due to the sampling methodology, certain items are checked infrequently.

Solution: In Figure 1, the formula in A4 is:

=INDEX (C4 : K4, 1, MATCH (1, INDEX (1-ISBLANK (C4 : K4), 1, 0), 0))


Although this formula deals with an array of cells, it ultimately returns a single value, so you do not need to use Ctrl+Shift+Enter when entering this formula.

Breaking It Down: Let's start from the inside. The ISBLANK function returns TRUE when a cell is blank and FALSE when a cell is non-blank. Look at the row of data in C4:K4. The ISBLANK(C4:K4) portion of the formula will return:

{TRUE, TRUE, FALSE, TRUE, TRUE, FALSE, TRUE, FALSE, TRUE}

Notice that this array is subtracted from 1. When you try to use TRUE and FALSE values in a mathematical formula, a TRUE value is treated as a 1, and a FALSE value is treated as a 0. By specifying 1-ISBLANK (C4:K4), you can convert the array of TRUE/FALSE values to 1s and 0s. Each TRUE value in the ISBLANK function changes to a 0. Each FALSE value changes to a 1. Thus, the array becomes:

{0,0,1,0,0,1,0,1,0}

The formula fragment 1 - I SBLANK (C4 : K4) specifies an array that is 1 row by 9 columns. However, you need Excel to expect an array, and it won't expect an array based on this formula fragment. Usually, the INDEX function returns a single value, but if you specify 0 for the column parameter, the INDEX function returns an array of values. The fragment INDEX (1-ISBLANK (C4:K4),1,0) asks for row 1 of the previous result to be returned as an array. Here's the result:

{0,0,1,0,0,1,0,1,0}

The MATCH function looks for a certain value in a one-dimensional array and returns the relative position of the first found value. =MATCH (1, Array, 0) asks Excel to find the position number in the array that first contains a 1. The MATCH function is the piece of the formula that identifies which column contains the first non-blank cell. When you ask the MATCH function to find the first 1 in the array of 0s and 1s, it returns a 3 to indicate that the first non-blank cell in C4 : K4 occurs in the third cell, or E4:

Formula fragment: MATCH (1, INDEX (1-ISBLANK (C4 : K4), 1, 0), 0)

Sub-result: MATCH (1, {0, 0, 1, 0, 0, 1, 0, 1, 0}, 0)

Result: 3

At this point, you know that the third column of C4 : K4 contains the first non-blank value. From here, it is a simple matter of using an INDEX function to return the value in that non-blank cell. =INDEX (Array, 1, 3) returns the value from row 1, column 3 of an array:

Formula fragment: =INDEX (C4 :K4, 1, MATCH (1, INDEX (1-ISBLANK (C4 : K4),1,0),0))

Sub-result: =INDEX (C4 : K4 , 1, 3)

Result: 4

Additional Details: If none of the cells are non-blank, the formula returns an #N/A error.

Alternate Strategy: Subtracting the ISBLANK result from 1 does a good job of converting TRUE/FALSE values to 0s and 1s. You could skip this step, but then you would have to look for FALSE as the first argument of the MATCH function:

=INDEX (C4 : K4, 1, MATCH (1, INDEX (1-ISBLANK (C4 : K4), 1, 0), 0))

Summary: The formula to return the first non-blank cell in a row starts with a simple ISBLANK function. Using INDEX to coax the string of results into an array allows this portion of the formula to be used as the lookup array of the MATCH function.

Source: http://www.mrexcel.com/forum/showthread.php?t=53223

CHAPTER 2

CALCULATE WORKDAYS FOR 5-, 6-, AND 7-DAY WORKWEEKS


Challenge: Calculate how many workdays fall between two dates. Excel's NETWORKDAYS function does this if you happen to work the five days between Monday and Friday inclusive. This topic will show you how to perform the calculation for a company that works 5, 6, or 7 days a week.

Background: The NETWORKDAYS function calculates the number of workdays between two dates, inclusive of the beginning and ending dates. You specify the earlier date as the first argument, the later date as the second argument, and optionally an array of holidays as the third argument. In Figure 2, cell C3 calculates only 5 workdays because February 16, 2009, is a holiday. This is a cool function, but if you happen to work Monday through Saturday, it will not calculate correctly for you.

Setup: Define a range named Holidays to refer to the range of holidays.

Solution: The formula in C3 is:

= SUMPRODUCT(--(COUNTIF(Holidays, ROW(INDIRECT(A3&":"&&B3)))=0), --(WEEKDAY(ROW(INDIRECT(A3&":"&&B3)),3)<6))

Although this formula deals with an array of cells, it ultimately returns a single value, so you do not need to use Ctrl+Shift+Enter when entering this formula.

Breaking It Down: The formula seeks to check two things. First, it checks whether any of the days within the date range are in the holiday list. Second, it checks to see which of the dates in the date range are Monday-through-Saturday dates.

You need a quick way to compare every date from A3 to B3 to the holiday list. In the current example, this encompasses only 8 days, but down in row 5, you have more than 300 days.

The formula makes use of the fact that an Excel date is stored as a serial number. Although cell A3 displays February 10, 2009, Excel actually stores the date as 39854. (To prove this to yourself, pressCtrl+' to enter Show Formulas mode. Press Ctrl+' to return to Normal mode.)

It is convenient that Excel dates in the modern era are in the 39,000 — 41,000 range, well within the 65,536 rows available in Excel 97-2003. The date corresponding to 65,536 is June 5, 2079, so this formula will easily continue to work for the next 70 years. (And if you haven't upgraded to Excel 2007 by 2079, well, you have a tenacious IT department.)

Excel starts evaluating this formula with the first INDIRECT function. The arguments inside INDIRECT build an address that concatenates the serial number for the date in A3 with the serial number for the date in B3. As you can see in the sub-result, you end up with a range that points to rows 39854:39861:

Formula fragment: INDIRECT(A3&" : "&B3)

Sub-result: INDIRECT ("39854 : 39861")

Normally, you would see something like "A2:IU2" as the argument for INDIRECT.

However, if you have ever used the POINT method of entering a formula and gone from column A to the last column, you will recognize that =SUM(2:2) is equivalent to =SUM (A2 : IV2) in Excel 2003 and =SUM(A2: XFD2) in Excel 2007.

The first step of the formula is to build a reference that is one row tall for each date between the start and end dates.

Next, the formula returns the ROW function for each row in that range. In the case of the dates in A3 and A4, the formula returns an array of eight row numbers (in this case, { 39854; 39855; 39856; ... ; 39861} ). This is a clever way of returning the numbers from the first date to the last date. In row 5, the ROW function returns an array of 364 numbers:

Formula fragment: ROW(INDIRECT(A3&" : "&B3))

Sub-result: {39854;39855;39856;39857;39858;39859;39860;39861}

Now you can compare the holiday list to the range of dates. =COUNTIF (Holidays, sub-result) counts how many times each holiday is in the range of dates. In this case, you expect the function to return a 1 if a holiday is found in the range of dates and a 0 if the holiday is not found. Because you want to count only the non-holiday dates, the formula compares the COUNTIF result to find the dates where the holiday COUNTIF is 0:

Formula fragment: --COUNTIF (Holidays, ROW (INDIRECT (A3&" : "&B3) ) ) =0

Result: {1;1;1;1;1;1;0;1;1}

For every date in the date range, the COUNTIF formula asks, "Are any of the company holidays equal to this particular date?" Figure 3 illustrates what is happening in the first half of the formula. Column E represents the values returned by the ROW function. Column F uses COUNTIF to see if any of the company holidays are equal to the value in column E. For example, in E3, none of the holidays are equal to 39855, so COUNTIF returns 0. However, in F8, the formula finds that one company holiday is equivalent to 39860, so COUNTIF returns 1.

In column G, you test whether the result of the COUNTIF is 1. If it is, the TRUE says to count this day.

In column H, the minus-minus formula converts each TRUE value in column G to 1 and each FALSE value in column G to 0.

In Figure 3, cells H2:H9 represent the virtual results of the first half of the formula, which finds the dates that are not holidays.

The second half of the formula uses the WEEKDAY function to find which dates are not Sundays. The WEEKDAY function can return three different sets of results, depending on the value passed as the Return Type argument. Figure 4 show the values returned for various Return Type arguments. In order to isolate Monday through Saturday, you could check to see if the WEEKDAY function with a Return Type of 1 is greater than 1. You could check to see if the WEEKDAY function with a Return Type of 2 is less than 7. You could check to see if the WEEKDAY function with a Return Type of 3 is less than 6. All these methods are equivalent.

The second half of the formula uses many of the tricks from the first half. The INDIRECT function returns a range of rows. The ROW function converts those rows to row numbers that happen to correspond to the range of dates. The WEEKDAY (, 3) function then converts those dates to values from 0 to 6, where 6 is equivalent to Sunday. The virtual result of the WEEKDAY function is shown in column L of Figure 5. The formula compares the WEEKDAY result to see if it is less than 6. This virtual result is shown in column M of Figure 5. Finally, a double minus converts the TRUE/FALSE values to 0s and 1s, as shown in column N. Basically, this says that we are working every day in the range, except for N7, which is a Sunday.

Formula fragment: -- (WEEKDAY (ROW (INDIRECT (A3&" : "&B3) ) , 3) <6)

Result: {1;1;1;1;1;1;0;1}

Finally, SUMPRODUCT multiplies the Not Holiday array by the Not Sunday array. When both arrays contain a 1, we have a workday. When either the Not Holiday array has a 0 (as in row 8) or the Not Sunday array has a 0 (as in row 7), the result is a 0. The final result is shown in the SUM function in P10: There are 6 workdays between the two dates.

As with most array solutions, this one formula manages to do a large number of sub-calculations to achieve a single result.

Additional Details: What if you work 7 days a week but want to exclude company holidays? The formula is simpler:

=SUMPRODUCT (--(COUNTIF(Holidays, ROW(INDIRECT(A2&":"&&B2)))=0))

The problem becomes trickier if days in the middle of the week are the days off. Say that you have a part-time employee who works Monday, Wednesday, and Friday. The Not Sunday portion of the formula now needs to check for 3 specific weekdays. Note that the Return Type 2 version of the WEEKDAY function never returns a 0. Because this version of the WEEKDAY function returns digits 1 through 7, you can use it as the first argument in the CHOOSE function to specify which days are workdays. Using =CHOOSE(WEEKDAY(Some Date,2),1,0,1,0,1,0,0) would be a way of assigning 1s to Monday, Wednesday, and Friday.

Because CHOOSE does not usually return an array, you have to enter the following formula, using Ctrl+Shift+Enter:

=SUMPRODUCT (--(COUNTIF(Holidays, ROW(INDIRECT(A3&":"&&B3)))=0),--(CHOOSE(WEEKDAY(ROW( INDIRECT(A3&":"&&B3))),2),1,0,1,0,1,0,0)))


Summary: This topic introduces the concept of creating a huge array from two simple values. For example, =ROW(INDIRECT("1:10000")) generates a 10,000-cell array filled with the numbers from 1 to 10,000. You can use this concept to test many dates while only specifying a starting and ending point, thus solving the NETWORKDAYS problem for any type of workweek.

Source: http://www.mrexcel.com/forum/showthread.php?t=69761

CHAPTER 3

STORE HOLIDAYS IN A NAMED RANGE

Challenge: The NETWORKDAYS and WORKDAY functions can take a list of company holidays as the third argument. If you store the list of holidays in AZ1: AZ10, there is a chance that someone will inadvertently delete a row, so you want to move the range of company holidays to a named range.

Solution: There is an easy way to convert the range of holidays to a named range. Follow these steps:

1. Type your company holidays as a column of dates in E1:E10.

2. In a blank cell, type =E 1: E 10. Do not press Enter. Instead, press the F9 key. Excel calculates the formula and returns an array of date serial numbers, as shown in Figure 6. Notice that everything after the equals sign is already selected.

3. Press Ctrl+C to copy the array to the Clipboard.

4. Press Esc to exit Formula Edit mode. The formula disappears.

5. Visit the Name dialog box. (In Excel 97-2003, select Insert, Name, Define. In Excel 2007, select Formulas, Define Name.)

6. Type Holidays as the name.

7. In the Refers To box, clear the current text. Type an equals sign. Press Ctrl+V to paste the array of dates to the box. Click OK.

Now you can use the named range Holidays as the third argument of the WORKDAY and NETWORKDAYS functions.

Gotcha: While these names work fine with WORKDAY and NETWORKDAYS, they fail in complex array formulas.

Summary: You can convert a range of dates to a named array to simplify the use of the WORKDAY and NETWORKDAYS functions.

CHAPTER 4

SUM EVERY OTHER ROW OR EVERY THIRD ROW

Challenge: In Figure 7, someone set up a worksheet with dollars in rows 2, 4, 6, 8, and so on and percentages in rows 3, 5, 7, 9, and so on. You want to sum only the dollars, which are stored in the even rows. While you're at it, you'd like to know how to sum the odd rows or every third row.

Solution: There are a lot of possible approaches to this problem, some of which require you to figure out which rows to sum.

• To sum the odd rows: =SUMPRODUCT (MOD (ROW (3: 100), 2), (C3: C100))

• To sum the even rows: =SUMPRODUCT (-- (MOD (ROW (2: 99), 2)=0), (C2:C99)) or =SUMPRODUCT (MOD (ROW (1:98),2), (C2:C99))

• To sum every third row (2, 5, 8, etc.): =SUMPRODUCT (-- (MOD (ROW (2 : 148),3)=2), (C2:C148)). See Figure 8


(Continues...)

Excerpted from Excel Gurus Gone Wild by Bill Jelen, Kitty Wilson. Copyright © 2009 Bill Jelen. Excerpted by permission of Holy Macro! Books.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Meet the Author

Bill Jelen is an Excel expert at mrexcel.com, a regular on TechTV Canada's Call for Help, and a video podcaster who is regularly listed in the iTunes top 50. He is the author of Learn Excel from Mr. Excel, Pivot Table Data Crunching, and 14 titles in the Excel for Professionals series. He lives in Akron, Ohio.

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