📅 最后修改于: 2020-11-29 08:33:48 🧑 作者: Mango
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要分析的字段。 Tableau具有许多内置函数，可帮助创建用于复杂计算的表达式。
以下是对不同功能类别的描述。
这些是用于数值计算的函数。他们仅将数字作为输入。以下是一些重要数字函数的示例。
| 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 |
字符串函数用于字符串操作。以下是一些重要的字符串函数和示例
| 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” |
Tableau具有各种日期功能，可以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，指示日期的一部分，例如-月，日或年。下表列出了一些重要的日期函数示例。
| 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 |
这些函数对某个单个值或表达式的结果求值，并产生布尔输出。
| 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. | |
| 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. |