Daisy - Mapping Format

Mapping Format - Choose

Choosing a suitable mapping format can at first sight appear to be a difficult and challenging process.

There are around 100 mapping formats in Daisy, where some are much more obscure than others. Which ones are best? Which ones do I use? etc. etc.

** Tip - It is strongly recommended that you print this topic and read it thoroughly!

Take a simple example of mapping say the transaction value in a shop, such as a supermarket. This will have lots of different values, such as 76.24, 23.45, 123.00 etc.

Given say 1,000 or so transactions, there is likely to be almost as many different values.

So mapping the data using the obvious mapping format of Numeric is probably not a good idea.

** Tip - Never choose a mapping format that will result in thousands of nodes unless that is exactly what you intend. You won't learn much in most cases!

A better approach is to choose a mapping format that will result in a manageable number of nodes. Typically, this is less than 20, although if you have a large screen, then up to 50 might be easily visualised.

Three mapping formats can achieve this :-

Break - Numeric is used to create up to five nodes with break values separating each.
Partition is used to split the data according to a step value. In our simple example, 10 might be suitable.
Tens extracts the tens from the data calling the nodes, 0, 10, 20 etc.

** Tip - Always use a mapping format that creates a limited set of nodes.

Our example used a numeric value. But what about dates, times and text?

Date mapping formats should be chosen so that a manageable number of nodes is generated.

Recommended mapping formats are :-

Break - Date does for dates what Break - Numeric does for numerics.
Day of Week maps the date as Sun, Mon, Tue etc.
Year-Month maps the date as something like 1996-Mar. This order is better than Mar-1996 as the nodes sort more readily into the correct order.

Recommended Time mapping formats are :-

Break - Time maps times to up five nodes.
Hour maps the time as 0, 1, 2 etc.

** Tip - Use Hour with the related Day of Week to analyse date and time based databases for significant patterns.

Recommended Text mapping formats depend very much on the data being mapped.

For instance if you are mapping names and addresses then Street Number and Street Name can be very useful.

Other useful Text mapping formats are :-

First Character, First Word, Last Word etc. are used to extract relevant parts of the text.
Phone Area, Phone Country, Phone Exchange and Phone Number are used to decode and format both nation-wide and International phone numbers.
Soundex is used to analyse names that sound alike.

Don't forget that with the simple mapping format of Text you can specify a width and a start position.

** New - An extra set of Tests mapping formats have now been added.

These test values and return 'True' or 'False' according to the value of the field and any criteria entered.

Some are straight validity tests such as Test Numeric Valid, Test Date Valid etc.
Others test values against simple properties such as Test All Alpha, Test Non-Zero, Test Negative etc.

Others tets against entered values such as , Test Contains, Test Equals etc.

Don't underestimate the power of this set of tests in validating a database and also in performing simple checks that locate records outside of acceptable criteria.

Remember though that the reason Daisy has a lot of mapping formats is that there are a myriad number of ways that databases can be analysed.

Go forward and experiment!

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