📅 最后修改于: 2020-12-02 05:38:31 🧑 作者: Mango
Apache Pig提供了各种内置函数，即eval，load，store，math， 字符串，bag和tuple函数。
以下是Apache Pig提供的评估函数列表。
| S.N. | Function & Description |
|---|---|
| 1 | AVG()
To compute the average of the numerical values within a bag. |
| 2 | BagToString()
To concatenate the elements of a bag into a string. While concatenating, we can place a delimiter between these values (optional). |
| 3 | CONCAT()
To concatenate two or more expressions of same type. |
| 4 | COUNT()
To get the number of elements in a bag, while counting the number of tuples in a bag. |
| 5 | COUNT_STAR()
It is similar to the COUNT() function. It is used to get the number of elements in a bag. |
| 6 | DIFF()
To compare two bags (fields) in a tuple. |
| 7 | IsEmpty()
To check if a bag or map is empty. |
| 8 | MAX()
To calculate the highest value for a column (numeric values or chararrays) in a single-column bag. |
| 9 | MIN()
To get the minimum (lowest) value (numeric or chararray) for a certain column in a single-column bag. |
| 10 | PluckTuple()
Using the Pig Latin PluckTuple() function, we can define a string Prefix and filter the columns in a relation that begin with the given prefix. |
| 11 | SIZE()
To compute the number of elements based on any Pig data type. |
| 12 | SUBTRACT()
To subtract two bags. It takes two bags as inputs and returns a bag which contains the tuples of the first bag that are not in the second bag. |
| 13 | SUM()
To get the total of the numeric values of a column in a single-column bag. |
| 14 | TOKENIZE()
To split a string (which contains a group of words) in a single tuple and return a bag which contains the output of the split operation. |