Any data analysis involves a lot of calculations. In Tableau, the calculation editor is used to apply calculations to the fields being analyzed. Tableau has a number of inbuilt functions which help in creating expressions for complex calculations.
Following are the description of different categories of functions.
These are the functions used for numeric calculations. They only take numbers as inputs. Following are some examples of important number functions.
|CEILING (number)||Rounds a number to the nearest integer of equal or greater value.||CEILING(2.145) = 3|
|POWER (number, power)||Raises the number to the specified power.||POWER(5,3) = 125|
|ROUND (number, [decimals])||Rounds the numbers to a specified number of digits.||ROUND(3.14152,2) = 3.14|
String Functions are used for string manipulation. Following are some important string functions with examples
|LEN (string)||Returns the length of the string.||LEN("Tableau") = 7|
|LTRIM (string)||Returns the string with any leading spaces removed.||LTRIM(" Tableau ") = "Tableau"|
|REPLACE (string, substring, replacement)||Searches the string for substring and replaces it with a replacement. If the substring is not found, the string is not changed.||REPLACE("GreenBlueGreen", "Blue", "Red") = "GreenRedGreen"|
|UPPER (string)||Returns string, with all characters uppercase.||UPPER("Tableau") = "TABLEAU"|
Tableau has a variety of date functions to carry out calculations involving dates. All the date functions use the date_part which is a string indicating the part of the date such as - month, day, or year. Following table lists some examples of important date functions.
|DATEADD (date_part, increment, date)||Returns an increment added to the date. The type of increment is specified in date_part.||DATEADD ('month', 3, #2004-04-15#) = 2004-0715 12:00:00 AM|
|DATENAME (date_part, date, [start_of_week])||Returns date_part of date as a string. The start_of_week parameter is optional.||DATENAME('month', #200404-15#) = "April"|
|DAY (date)||Returns the day of the given date as an integer.||DAY(#2004-04-12#) = 12|
|NOW( )||Returns the current date and time.||NOW( ) = 2004-04-15 1:08:21 PM|
These functions evaluate some single value or the result of an expression and produce a boolean output.
|IFNULL (expression1, expression2)||The IFNULL function returns the first expression if the result is not null, and returns the second expression if it is null.||IFNULL([Sales], 0) = [Sales]|
|ISDATE (string)||The ISDATE function returns TRUE if the string argument can be converted to a date, and FALSE if it cannot.||
ISDATE("11/05/98") = TRUE
ISDATE("14/05/98") = FALSE
|MIN(expression)||The MIN function returns the minimum of an expression across all records or the minimum of two expressions for each record.|
|AVG(expression)||Returns the average of all the values in the expression. AVG can be used with numeric fields only. Null values are ignored.|
|COUNT (expression)||Returns the number of items in a group. Null values are not counted.|
|MEDIAN (expression)||Returns the median of an expression across all records. Median can only be used with numeric fields. Null values are ignored.|
|STDEV (expression)||Returns the statistical standard deviation of all values in the given expression based on a sample of the population.|
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