Data Tables and Arrays

Look at the following data What could it mean? What are the missing values? £8.88 9.0 10%

Here is the complete dataset Notice ‘Records’ and ‘Fields’ have been added to give a context (you now have ‘information’)

Formatting Fields are stored with particular ‘Formats’ to help control appropriate input

Summary You can have several different ‘formats’ e.g. Text, Number, Hyperlink etc…. The numbers in the dataset are formatted appropriately to make the table easy to read and understand. The ‘sources table’ you created for Skills Builder 1 only contained ‘sources’ and text fields. This table also contains numbers – and they can be used for calculations. What software application is best for calculations and ‘number crunching’?

Open Spreadsheet 1! SB2 L1 VTable.xls

In this lesson students are learning about: Arrays How to look up information in an array

At the end of this lesson students will be able to: define an array describe how to look up information in a vertical data table

Task: Before you do any calculations, I want you to look up in the table the information that goes with information I give you….

Lookup For ‘Item5’, what is the ‘Discount’? 5% For ‘Item12’, what is the ‘Source’? www.link12 For ‘Item10’, what is the ‘Weight’? 10.0kg

The process you automatically undertook to achieve the answer… Describe where you started from… how did you move within the table? and where did you end up? The direction of travel is always: top down the first column of the table (spreadsheet column B) to find the match, then right along the same row (left to right) to locate the desired information.

Like so…..

What if I know a particular ‘Weight’ – can you look up other information that goes with it? YES BUT… The Lookup follows a similar principle as before except it has a different starting point (in this case it is ‘Weight’ instead of ‘Item number’) E.g. If the ‘Weight’ is 6.0, what is the ‘Discount’? 6%

So how can we get a Spreadsheet to automatically return answers to these questions? A spreadsheet can be used to return this data very quickly. We will look at the ‘function’ that does this next lesson but it is important that you first understand what an ‘array’ is…

Tables and arrays Look at ‘Table arrays sheet’ on SB2 L1 VTable.xls It shows the same table with the two examples just used (‘Items’ and ‘Weight’), colour-coded and labelled Array V1 (blue) and Array V2 (pink). an array is a range of cells specified from top-left to bottom-right.

Array properties One spreadsheet column, e.g. spreadsheet columns F – K, can be in different arrays and thus can have different array-specific labels. For a successful lookup to occur the user enters what is known is in Column 1, and what needs to be looked up is in a column to the right of it.

For example For ‘Item7’, where is the ‘Discount’? Column 5

For example If the ‘Weight’ is 6.0, where is the ‘Discount’? pink Column 2

Defining a new array You can define as many arrays as you need. You will need to do this in preparation for next lesson. Your Teacher will now show you haw to set up an array in a spreadsheet.

Task You must now set up at least two arrays in SB2 L1 VTable.xls pick a starting point for your own array and colour-code it number your array’s columns and code them in the same colour type in the range of cells within your array. ask each other ‘If …’ questions based on your array and answer them by giving the array column number.

And finally (1) an array defines a range of cells from top-left to bottom-right (2) looking up information in an array takes three steps: (i) name information you know, (ii) match it in first column of the array, (iii) move right to locate the information you want.