我试图从tweets内部捕获图片url。

REGISTER 'hdfs:///user/cloudera/elephant-bird-pig-4.1.jar';
REGISTER 'hdfs:///user/cloudera/elephant-bird-core-4.1.jar';
REGISTER 'hdfs:///user/cloudera/elephant-bird-hadoop-compat-4.1.jar';

--Load Json

loadJson = LOAD '/user/cloudera/tweetwall' USING com.twitter.elephantbird.pig.load.JsonLoader('-nestedLoad') AS (json:map []);
B = FOREACH loadJson GENERATE flatten(json#'tweets') as (m:map[]);
tweetText = FOREACH B GENERATE FLATTEN(m#'text') as (str:chararray);

中间日期如下所示：

(@somenameontwitter your nan makes me laugh with some of the things she comes out with like http://somepics.com/my.jpg)

然后，我尝试执行以下操作以仅返回图像url：

x = foreach tweetText generate REGEX_EXTRACT_ALL(str, '((http)(.*)(.jpg|.bmp|.png))');

dump x;

但这似乎行不通。我也一直在尝试过滤器，但没有结果。
即使在使用.*尝试上述操作时，它也会返回空结果（）或（（））
我不擅长regex，对pig也很陌生，所以我可能错过了一些简单的东西。
更新
输入数据示例

{"tweets":[{"created_at":"Sat Nov 01 23:15:45 +0000 2014","id":5286804225,"id_str":"5286864225","text":"@Beace_ your nan makes me laugh with some of the things she comes out with blabla http://t.co/b7hjMWNg is an url, but not a valid one http://www.something.com/this.jpg should be a valid url","source":"\u003ca href=\"http:\/\/twitter.com\/download\/iphone\" rel=\"nofollow\"\u003eTwitter for iPhone\u003c\/a\u003e","truncated":false,"in_reply_to_status_id":52812992878592,"in_reply_to_status_id_str":"522","in_reply_to_user_id":398098,"in_reply_to_user_id_str":"3","in_reply_to_screen_name":"Be_","user":{"id":425,"id_str":"42433395","name":"SAINS","screen_name":"sa3","location":"Lincoln","profile_location":null,"description":"","url":null,"entities":{"description":{"urls":[]}},"protected":false,"followers_count":92,"friends_count":526,"listed_count":0,"created_at":"Mon May 25 16:18:05 +0000 2009","favourites_count":6,"utc_offset":0,"time_zone":"London","geo_enabled":true,"verified":false,"statuses_count":19,"lang":"en","contributors_enabled":false,"is_translator":false,"is_translation_enabled":false,"profile_background_color":"EDECE9","profile_background_image_url":"http:\/\/abs.twimg.com\/images\/themes\/theme3\/bg.gif","profile_background_image_url_https":"https:\/\/abs.twimg.com\/images\/themes\/theme3\/bg.gif","profile_background_tile":false,"profile_image_url":"http:\/\/pbs.twimg.com\/profile_images\/52016\/DGDCj67z_normal.jpeg","profile_image_url_https":"https:\/\/pbs.twimg.com\/profile_images\/526\/DGDCj67z_normal.jpeg","profile_banner_url":"https:\/\/pbs.twimg.com\/profile_banners\/424395\/13743515","profile_link_color":"088253","profile_sidebar_border_color":"D3D2CF","profile_sidebar_fill_color":"E3E2DE","profile_text_color":"634047","profile_use_background_image":true,"default_profile":false,"default_profile_image":false,"following":false,"follow_request_sent":false,"notifications":false},"geo":null,"coordinates":null,"place":null,"contributors":null,"retweet_count":0,"favorite_count":1,"entities":{"hashtags":[],"symbols":[],"user_mentions":[{"screen_name":"e_","name":"\u2601\ufe0f effy","id":3998,"id_str":"398","indices":[0,15]}],"urls":[]},"favorited":false,"retweeted":false,"lang":"en"}]}