Filter 球拍/方案过滤
我将如何过滤此文件以显示所有蔬菜?先谢谢你Filter 球拍/方案过滤,filter,scheme,racket,Filter,Scheme,Racket,我将如何过滤此文件以显示所有蔬菜?先谢谢你 ("Pecan" . (1982 .("nut". "AL"))) ("Blackberry" . (2004 .("fruit". "AL"))) ("Peach" . (2006 .("fruit". "AL"))) ("Rice" . (2007 .("grain". "AR"))) ("Orange" . (2005 .("fruit". "FL"))) ("Huckleberry" . (2000 .("fruit". "ID"))
("Pecan" . (1982 .("nut". "AL")))
("Blackberry" . (2004 .("fruit". "AL")))
("Peach" . (2006 .("fruit". "AL")))
("Rice" . (2007 .("grain". "AR")))
("Orange" . (2005 .("fruit". "FL")))
("Huckleberry" . (2000 .("fruit". "ID")))
("Blackberry" . (2004 .("fruit". "KY")))
("Strawberry" . (1980 .("fruit". "LA")))
("WildBlueberry" . (1991 .("fruit". "ME")))
("BlueCrab" . (2000 .("food". "MD")))
("HoneycrispApple" . (2006 .("fruit". "MN")))
("Pumpkin" . (2000 .("fruit". "NH")))
("Chile" . (1965 .("vegetable". "NM")))
("Blueberry" . (2001 .("fruit". "NC")))
("ChokeCherry" . (2007 .("fruit". "ND")))
("WaterMelon" . (2007 .("vegetable". "OK")))
("Pear" . (2000 .("fruit". "OR")))
("Hazelnut" . (2000 .("nut". "OR")))
("Peach" . (1984 .("fruit". "SC")))
("Tomato" . (2003 .("fruit". "TN")))
("Jalapeno" . (1995 .("vegetable". "TX")))
("Apple" . (2000 .("fruit". "WA")))
将所有元素打包到一个列表中(在下面的代码中称为
lst
),并在其上运行此筛选器:
(filter (lambda (x) (string=? "vegetable" (caddr x)))
lst)
=> '(("Chile" 1965 "vegetable" . "NM")
("WaterMelon" 2007 "vegetable" . "OK")
("Jalapeno" 1995 "vegetable" . "TX"))
非常感谢!,这正是我开始工作所需要的