Tableau 简明教程

Tableau - Functions

任何数据分析都涉及大量计算。在 Tableau 中，计算编辑器用于将计算应用于正在分析的字段。Tableau 具有许多内置函数，有助于创建复杂计算的表达式。

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.

以下是不同函数类别的说明。

Following are the description of different categories of functions.

  1. Number Functions

  2. String Functions

  3. Date Functions

  4. Logical Functions

  5. Aggregate Functions

Number Functions

这些是用于数字计算的函数。它们仅将数字作为输入。以下是一些重要的数字函数示例。

These are the functions used for numeric calculations. They only take numbers as inputs. Following are some examples of important number functions.

Function

Description

Example

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

字符串函数用于字符串处理。以下是带有示例的一些重要的字符串函数

String Functions are used for string manipulation. Following are some important string functions with examples

Function

Description

Example

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"

Date Functions

Tableau 具有各种日期函数来执行涉及日期的计算。所有日期函数都使用 date_part ，这是一个字符串，指定日期的一部分，例如月份、日期或年份。下表列出了一些重要的日期函数示例。

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.

Function

Description

Example

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

Logical Functions

这些函数计算某些单一值或表达式的结果，并生成布尔输出。

These functions evaluate some single value or the result of an expression and produce a boolean output.

Function

Description

Example

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.

Aggregate Functions

Function

Description

Example

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.