Tableau Calculated Fields

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En provenance du cours de University of California, Davis

Visual Analytics with Tableau

554 notes

University of California, Davis

Visual Analytics with Tableau

554 notes

Cours 3 sur 5 dans Specialization Data Visualization with Tableau

In this third course of the specialization, we’ll drill deeper into the tools Tableau offers in the areas of charting, dates, table calculations and mapping. We’ll explore the best choices for charts, based on the type of data you are using. We’ll look at specific types of charts including scatter plots, Gantt charts, histograms, bullet charts and several others, and we’ll address charting guidelines. We’ll define discrete and continuous dates, and examine when to use each one to explain your data. You’ll learn how to create custom and quick table calculations and how to create parameters. We’ll also introduce mapping and explore how Tableau can use different types of geographic data, how to connect to multiple data sources and how to create custom maps.

À partir de la leçon

Dates

This module highlights the important topic of dates within Tableau. You will be able to differentiate between discrete and continuous dates and when to use each. You will be able to use date hierarchies and use the date field to better customize your charts. You will be able to convert between discrete and continuous dates and know when and why you want to switch from one to the other. You will create dates using calculated fields.

Introduction to Dates1:03

Discrete vs. Continuous Dates2:36

Date Hierarchies3:33

Converting Discrete and Continuous Dates2:31

Tableau Calculated Fields4:59

Rencontrer les enseignants

Suk S. Brar, M.B.A.
Lead Business Consultant
Blue Shield of California

Welcome to this final lesson in this module.

Previously, you discovered how to convert between discrete and

continues dates and why you would want to switch from one date type to the other.

After this lesson, you will be able to create dates using

calculated fields for those moments when a date field is not available.

So, we will continue to use the superstore data set.

Now, we will first open that calculated box dialog window lets right

click anywhere in the data window or sidebar and click on Create calculated field.

If you right clicked on a particular dimension or measure to create your calculation,

then it will appear in the calculated field window in the formula text area.

To filter the functions to show only the date functions,

let's use a dropdown box and select date.

Now that we got our function selected,

let's first define the potential values for DATEPART,

which is used in many of the date functions.

DATEPART can hold the following values.

Seconds, 0-60.

Minutes, 0-59.

Hours 0-23.

Days, 1-31.

Weekdays, 1-7 or by name such as Sunday.

Week, 1-52. Day of year, 1-365.

Month,1-12 or by name such as January.

Quarter, 1-4 or a four digit representation for year.

Now that you know the different values,

let's examine the date functions.

The DATEADD function allows you to specify a portion of a date and increase it.

The number that you use for the interval will change the date by increasing the DATEPART.

The DATEDIFF function allows you to return the difference between date

one and date two expressed in units determined by DATEPART.

The start of week parameter is optional and if it is not

defined then the start of week is determined by the associated data source.

The DATENAME function returns a DATEPART parameter of the date as a string.

Again, the start of week parameter is optional.

The DATEPARSE function essentially works in reverse of DATENAME

by converting the string into a date time with specified format.

If the string does not match the date time format,

then it will return a value of null.

The DATEPART function allows you to return a specified DATEPART as an integer.

Again, the start of week parameter is optional.

The DATETRUNC function truncates date to

the accuracy of the DATEPART that you specify in the function.

In other words, it rounds towards that DATEPART.

The DAYDATE function returns a day of the specified date as an integer.

The ISDATE string is a logical test that is

also included in the list of logical functions.

It tests a strange determine if it is a valid date,

a true, or false.

The MAX function exists in several categories of functions including the date functions.

The MAX function returns a maximum of a single expression

across all records or the maximum of two expressions for each record.

The two arguments must be the same type.

This function will return a value of null,

if either argument is null.

Like the max function above,

the MIN function is commonly used as a number function but can also be used with dates.

The MIN function returned the minimum of a single expression across

all records or the minimum of two expressions for each record.

MIN returns the value of No if either of the two arguments is null.

The MONTHDATE function returns

the month of the specified date as an integer just like the DAY function does for DAY.

The NOW function returns a current date and time,

the TODAY function returns a current and date.

The YEARDATE function returns a year of the specified date as an integer.

You can use any of these functions to create a new date variable to use in your analyses.

Let's look at an example.

If you want to create a variable that shows today's date,

we can use the NOW function.

And let's change the name of our variable to today's date.

Now we have a variable that will show us today's date in our dimensions.

So far in this course,

you have learned the difference between discrete and continuous dates,

how to use date hierarchies,

how to convert between discrete and continuous dates,

why you would want to switch from one date type to the other,

and how to create dates using

calculated fields for those moments when the date field is not available.

Remember to continue to practice everything you are learning. See you next time.

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