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What is a result vector in Excel?

Published in Excel Lookup Functions 4 mins read

In Excel, a result vector is a dedicated range of cells used primarily within lookup functions, such as the LOOKUP function, to specify where the desired output should be found. It acts as the destination range from which a corresponding value is retrieved after a successful search operation.

Understanding the Role of a Result Vector

A result vector defines the exact location where Excel will find and return a value once your specified search item (the lookup value) has been located within another designated range, known as the lookup_vector or lookup_range. The core idea is that if the lookup_value is found at a certain position (e.g., the third item) within the lookup_vector, then the value returned will be from the same relative position (the third item) within the result_vector.

Key Characteristics of a Result Vector

To effectively use a result vector, it's important to understand its specific properties:

  • Range Type: A result vector must always be a one-row or one-column range. This means it can be a horizontal array of cells (e.g., A1:E1) or a vertical array of cells (e.g., B1:B10), but not a multi-row and multi-column block.
  • Purpose: Its primary function is to serve as the source from which the final result is returned. It separates the data you are searching in from the data you want to retrieve from.
  • Sizing Constraint: The result vector must be the same size (have the same number of cells) as the lookup_vector or lookup_range it is associated with. This ensures a one-to-one correspondence between the positions in both ranges.
  • Optionality: In the LOOKUP function's vector form (LOOKUP(lookup_value, lookup_vector, [result_vector])), the result vector argument is optional.
  • Default Behavior (if omitted): If the result vector is omitted when using the LOOKUP function, Excel will automatically return the result directly from the lookup_vector itself. In this scenario, the lookup_vector serves a dual purpose: both as the search range and the result range.

Result Vector in Action: The LOOKUP Function

The LOOKUP function is a classic example where the concept of a result vector is fundamental. It allows you to find a value in one range and return a corresponding value from another range.

The syntax for the vector form of the LOOKUP function is:
LOOKUP(lookup_value, lookup_vector, [result_vector])

  • lookup_value: The value you want to find.
  • lookup_vector: The one-row or one-column range where you expect to find the lookup_value. This range must be sorted in ascending order for LOOKUP to work correctly.
  • result_vector: (Optional) The one-row or one-column range from which you want to return the corresponding result. As mentioned, it must be the same size as the lookup_vector.

Example Scenario

Consider a list of student IDs, their scores, and corresponding grades in an Excel worksheet:

Student ID Score Grade
101 88 B
102 95 A
103 72 C
104 65 D
105 90 A

Suppose you want to quickly find the Grade for a specific Student ID using the LOOKUP function.

To find the grade for Student ID 103:

  • lookup_value: 103 (the Student ID you are searching for)
  • lookup_vector: The range containing the Student IDs, for example, A2:A6 (which contains {101, 102, 103, 104, 105}). This is the range where Excel will search for '103'.
  • result_vector: The range containing the Grades, for example, C2:C6 (which contains {"B", "A", "C", "D", "A"}). This is the range from which Excel will pull the answer.

The formula would be: =LOOKUP(103, A2:A6, C2:C6)

Excel would first find 103 in the lookup_vector A2:A6. Since 103 is the third value in this range, Excel then looks at the third value in the result_vector C2:C6, which is "C", and returns "C" as the result.

For more details on lookup functions in Excel, you can refer to the official Microsoft documentation for the LOOKUP function.

Practical Implications

Using a result vector in functions like LOOKUP offers flexibility by allowing you to search in one column or row and return a value from a completely different, non-adjacent column or row. This is particularly useful when your data is structured in a way that separates identifier columns from descriptive or result-oriented columns. It provides a clear separation of concerns between your search criteria and the desired outcome.