Alias
Definition: An alternate name for members in a dimension. It makes a label appear differently in the view.
Discrete dimensions only. Aliases cannot be used for continuous dimensions, dates, or measures.
Histogram
Looks like a bar chart
Each bar represents data points that fall within a given range (a “bin”)
Geographic Role
Tableau assigns latitude and longitude values to every geographic role.
How to assign a geographic role to a field: In the data pane, click the data type icon next to the field, select Geographic Role, and then select the precise role needed.
How to change a data field’s data type
Can be done on either the Data Source page or the Data pane.
Click the icon to the left of the field name and choose the new type.
Relationships vs. Joins
Relationships:
- The primary means of combining data in Tableau
- More dynamic and flexible than joins
- Are displayed as flexible noodles between logical tables
- Require you to select matching fields between two logical tables
- Do not require you to select join types
- Make all row and column data from related tables potentially available in the data source
- Maintain each table’s level of detail in the data source and during analysis
- Create independent domains at multiple levels of detail. Tables aren’t merged together in the data source.
- During analysis, create the appropriate joins automatically, based on the fields in use.
- Do not duplicate aggregate values (when Performance Options are set to Many-to-Many)
- Keep unmatched measure values (when Performance Options are set to Some Records Match)
Joins:
- No longer the primary means of combining data in Tableau
- More static than relationships
- Are displayed with Venn diagram icons between physical tables
- Require you to select join types and join clauses
- Joined physical tables are merged into a single logical table with a fixed combination of data
- May drop unmatched measure values
- May duplicate aggregate values when fields are at different levels of detail
- Support scenarios that require a single table of data, such as extract filters and aggregation
Types of LOD Expressions
There are three LOD expressions:
- FIXED - computes a value using the specified dimensions without reference to the dimensions in the view
- INCLUDE - computes a value using the specified dimensions in addition to whatever dimensions are in the view
- EXCLUDE - declares dimensions to omit from the view level of detail
Joins
The merging of multiple data sources based on each source’s leftmost column of data.
There are four join types:
- Inner: matches in both tables
- Left: all values from the left table and any matches from the right table. When a value in the left table doesn’t have a match in the right table, you see a null value.
- Right: all values from the right table and any matches from the left table. When a value in the right table doesn’t have a match in the left table, you see a null value.
- Full Outer: all values from both tables. When a value from either table doesn’t have a math with the other table, you see a null value.
Unions
Combining data sources by appending rows of one table into another table.
Fields (aka column headers) must match for the union to work correctly.
Discrete Date Parts vs. Continuous Date Values
Discrete Date Parts
- Blue
- Produce headers in a view
- Behave like dimensions
Continuous Date Values
- Green
- Produce axes in a view
- Behave like measures
Parameter
A workbook variable that replaces a constant value in a calculation, filter, or reference line.
Parameters can depend on the input of the user.
Aggregation type: Dimension
Returns a list of all unique values in a measure or dimension.
Example: if the measure contains values [1, 2, 2, 3] the Dimension aggregation will return [1, 2, 3]
Aggregation type: Attribute
Returns the value only if all rows have the same value, otherwise it returns an asterisk.
Dimension vs. Measure
Dimension = qualitative values. Examples: names, dates, geographical data
Measure = numeric, quantitative values. Measures are aggregated when added to a view. The type of default aggregation depends on the context of the view.
Dimensions and measures can be either discrete or continuous.
Data Sources: Live Connection vs. Extract
Live connection: direct connection to underlying data, providing real-time data. Fresher data but slower performance. Stored in storage (hard drive) as opposed to memory (RAM).
Extract: a snapshot of data. Optimized for aggregation. Faster performance but less fresh data. .tde or .hyper file types. Extracts are stored in memory (RAM) as opposed to storage (hard drive).
Discrete fields vs. Continuous fields
Discrete = Blue. Finite. Column headers.
Continuous = Green. Infinite. Axes.
Calculated Field
Calculated fields allow you to create new data from data that already exists in your data source. When you create a calculated field, you are essentially creating a new field (or column) in your data source, the values or members of which are determined by a calculation that you control. This new calculated field is saved to your data source in Tableau, and can be used to create more robust visualizations. But don’t worry: your original data remains untouched.
You create calculated fields using calculations. There are three main types of calculations you can use to create calculated fields in Tableau:
- Basic calculations - Basic calculations allow you to transform values or members at the data source level of detail (a row-level calculation) or at the visualization level of detail (an aggregate calculation).
- Level of Detail (LOD) expressions - Just like basic calculations, LOD calculations allow you to compute values at the data source level and the visualization level. However, LOD calculations give you even more control on the level of granularity you want to compute. They can be performed at a more granular level (INCLUDE), a less granular level (EXCLUDE), or an entirely independent level (FIXED) with respect to the granularity of the visualization.
- Table calculations - Table calculations allow you to transform values at the level of detail of the visualization only.
Table Calculation
A special type of calculated field that computes on the local data in Tableau. It transforms values in a visualization. They’re calculated based on what is currently in the visualization.
Examples:
- Transform values into rankings
- Transform values to show running totals
- Transform values to show percent of total
Crosstab
Just another term for a text table
In the Worksheet menu, there is a “duplicate as crosstab” option which will create a new worksheet with the data formatted as a text table.
Order of Operations
- Extract Filters
- Data Source Filters
- Context Filters
- -Sets, conditional filters, top N, Fixed LOD - Dimension Filters
- -Include/Exclude LOD, data blending - Measure Filters
- -Forecasts, table calcs, clusters, totals - Table Calc Filters
- -Trend lines, reference lines
(EDC-DMT)
https://help.tableau.com/current/pro/desktop/en-us/order_of_operations.htm
1.1.1. Choose an appropriate data source
https://help.tableau.com/current/pro/desktop/en-us/datasource_plan.htm
Important distinction between the Tableau data source and the source data itself. A Tableau data source is the link between your source data and Tableau. A Tableau data source is created when connecting to data.
Important distinction between a Tableau data source and a data connection. A single Tableau data source may contain multiple data connections to different databases or files.
1.1.9. Replace the connected data source with another data source for an existing chart or sheet
While viewing a sheet, go to Data -> New Data Source. Select the replacement data source. Both data sources should then be listed at the top of the data pane.
In order to replace a data source, there must be at least one field in the view.
With at least one field in the view, go to Data -> Replace data source. A dialog window appears to allow the user to perform the replacement.
How to create Data Source Filters and Extract Filters
Data source filter: On the data source page, in the top right corner, it says “Filters”. Click “Add”. When creating an extract from a data source, any existing data source filters will be recommended to become extract filters.
Extract filter: On the data source page, click the radio button for Extract, then click edit. In the dialog window that appears, extract filters can be created.
Calculation building blocks
There are four basic components to calculations in Tableau:
- Functions - Statements used to transform the values or members in a field.
- Fields - Dimensions or measures (columns) from your data source.
- Operators - Symbols that denote an operation.
- Literal expressions - Constant values that are represented “as is”, such as “Profitable” and “Unprofitable”.
Additionally, calculations can contain:
- Parameters - Placeholder variables that can be inserted into calculations to replace constant values.
- Comments - Notes about a calculation or its parts, not included in the computation of the calculation.
Transforming Data
Two main types of operations to transform data
- Field operations. Change the field type or geographic role.
- Value operations. Rename the field values themselves.
