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Introducing Array Formulas 17
Figure 17.15 shows an example in which the range A1:A10 is named Data. The SMALL function is evaluated
three times, each time with a different second argument. The first time, the SMALL function has a second
argument of 1, and it returns –5. The second time, the second argument for the SMALL function is 2,
and it returns 0 (the second smallest value in the range). The third time, the SMALL function has a second
argument of 3 and returns the third smallest value of 2.
FIGURE 17.15
An array formula returns the sum of the three smallest values in A1:A10.
Therefore, the array that’s passed to the SUM function is
{-5,0,2)
The formula returns the sum of the array (–3).
Counting text cells in a range
Suppose that you need to count the number of text cells in a range. The COUNTIF function seems like it
might be useful for this task — but it’s not. COUNTIF is useful only if you need to count values in a range
that meet some criterion (for example, values greater than 12).
To count the number of text cells in a range, you need an array formula. The following array formula uses
the IF function to examine each cell in a range. It then creates a new array (of the same size and dimensions
as the original range) that consists of 1s and 0s, depending on whether the cell contains text. This new
array is then passed to the SUM function, which returns the sum of the items in the array. The result is a
count of the number of text cells in the range.
CROSS-REF
{=SUM(IF(ISTEXT(A1:D5),1,0))}
This general array formula type (that is, an IF function nested in a SUM function) is very useful
for counting. Refer to Chapter 14 for additional examples.
Figure 17.16 shows an example of the preceding formula in cell C8. The array created by the IF function is
{0,1,1,1;1,0,0,0;1,0,0,0;1,0,0,0;1,0,0,0}
Notice that this array contains four rows of three elements (the same dimensions as the range).
A slightly more efficient variation on this formula follows:
{=SUM(ISTEXT(A1:D5)*1)}
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