Hive内嵌字符处理函数：regexp_extract,regexp_replace,split，replace，translate-CFANZ编程社区

1.Hive内嵌函数说明

官方地址：hive函数大全官方地址

Hive字符处理函数系列1：hive内嵌字符串函数1

String Functions

Return Type	Name(Signature)	Description
	regexp_extract(string subject, string pattern, int index)	Returns the string extracted using the pattern. For example, regexp_extract('foothebar', 'foo(.?)(bar)', 2) returns 'bar.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '\\s' is necessary to match whitespace, etc. The 'index' parameter is the Java regex Matcher group() method index. See docs/api/java/util/regex/Matcher.html for more information on the 'index' or Java regex group() method.. 抽取字符串subject中符合正则表达式pattern的第index个部分的子字符串，注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格 hive> select regexp_extract('foothebar', 'foo(.?)(bar)', 2) ---注意2是匹配分组的 'bar.'**
	regexp_replace(string INITIAL_STRING, string PATTERN, string REPLACEMENT)	Returns the string resulting from replacing all substrings in INITIAL_STRING that match the java regular expression syntax defined in PATTERN with instances of REPLACEMENT. For example, regexp_replace("foobar", "oo\|ar", "") returns 'fb.' Note that some care is necessary in using predefined character classes: using '\s' as the second argument will match the letter s; '\\s' is necessary to match whitespace, etc.. 按照Java正则表达式PATTERN将字符串INTIAL_STRING中符合条件的部分成REPLACEMENT所指定的字符串，如里REPLACEMENT这空的话，抽符合正则的部分将被去掉如：regexp_replace("foobar", "oo\|ar", "") = 'fb.' 注意些预定义字符的使用，如第二个参数如果使用'\s'将被匹配到s,'\\s'才是匹配空格
string	replace(string A, string OLD, string NEW)	Returns the string A with all non-overlapping occurrences of OLD replaced with NEW (as of Hive 1.3.0 and 2.1.0). Example: select replace("ababab", "abab", "Z"); returns "Zab".
	split(string str, string pat)	Splits str around pat (pat is a regular expression).. 按照正则表达式pat来分割字符串str,并将分割后的数组字符串的形式返回
string	translate(string\|char\|varchar input, string\|char\|varchar from, string\|char\|varchar to)	Translates the input string by replacing the characters present in the `from` string with the corresponding characters in the `to` string. This is similar to the `translate` function in PostgreSQL. If any of the parameters to this UDF are NULL, the result is NULL as well. (Available as of Hive 0.10.0, for string types) Char/varchar support added as of Hive 0.14.0. 解释： hive>select translate('abcdefga','abc','wo') wodefgw 注意，结果不是wodefga， hive>select replace('abcdefga','abc','wo') wodefga 注意，两个结果，这就是replace和translate的区别。
map<string,string>	str_to_map(text[, delimiter1, delimiter2])	Splits text into key-value pairs using two delimiters. Delimiter1 separates text into K-V pairs, and Delimiter2 splits each K-V pair. Default delimiters are ',' for delimiter1 and ':' for delimiter2. 解释：使用两个分隔符将文本拆分为键值对。分隔符1将文本分成K-V对，分隔符2分割每个K-V对。对于分隔符1默认分隔符是 ','，对于分隔符2默认分隔符是 '='。 hive> select str_to_map(concat(path_id,':',filter_name )) ---是map类型的 from FDM_SOR.T_FIBA_MULTI_UBA_CFG_PATH_DETAIL_D group by path_id,filter_Name hive>

2.split,regexp_replace,regexp_extract的使用

2.1 split函数，支持使用正则表达式对字符串进行切割，返回值为数组

SELECT 
SPLIT('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1','\\?') [0] AS A,  
--对url进行使用？进行切割，返回值是数组，这里取？前面的值。
SPLIT('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1','\\?') [1] AS A1,
SPLIT('http://facebook.com/index.html','\\?') [0]   AS B ,
SPLIT('http://facebook.com/index.html','\\?') [1] AS B1,
SPLIT('http://facebook.com/path1/p.php?k1=v1&k2=v2#Ref1','\\\w\\/') [0] AS C1
FROM  FDM_SOR.T_PLPLFIS_TB_LOAN_APPLY_CEBANK_ED

Hive内嵌字符处理函数：regexp_extract,regexp_replace,split，replace，translate_Hive函数

注意：所有正则表达式中的预定义字符比如？，}，|等需要在这里用\\进行反转义才能表达本意。比如正则表达式中\w表示匹配字母，所以也属于预定义字符，单独的\w表示匹配的是字母w，而\\\w才表示匹配字母。

2.2. regexp_replace函数，比较简单，难的是里面参数正则表达式的书写。

select 
case when regexp_replace(uniscid,'[0-9A-HJ-NPQRTUWXY]{2}\\d{6}[0-9A-HJ-NPQRTUWXY]{10}','~~fbietl~~') = '~~fbietl~~' then uniscid 
       else null end uniscid,
from fdm_sor.aaaaaaaaaaaaaaa;

2.3 replace和translate的区别

replace：字符串级别的代替
translate：字符级别的代替 hive>select translate('abcdefga','abc','wo') wodefgw 注意，结果不是wodefga， hive>select replace('abcdefga','abc','wo') wodefga 注意，两个结果，这就是replace和translate的区别。