Question

我将一堆变量粘贴到一个明确的网址列表中

id <- 1:10
animal <- c("dog", "cat", "fish")
base <- "www.google.com/"

urls <- paste0(base, "id=", id, "search=", animal)

输出如下：

 [1] "www.google.com/id=1search=dog"  "www.google.com/id=2search=cat"  "www.google.com/id=3search=fish"
 [4] "www.google.com/id=4search=dog"  "www.google.com/id=5search=cat"  "www.google.com/id=6search=fish"
 [7] "www.google.com/id=7search=dog"  "www.google.com/id=8search=cat"  "www.google.com/id=9search=fish"
[10] "www.google.com/id=10search=dog"

但实际上我希望ids和animals按顺序重复：

 [1] "www.google.com/id=1search=dog"  "www.google.com/id=2search=dog"  "www.google.com/id=3search=dog"
 [4] "www.google.com/id=4search=dog"  "www.google.com/id=5search=dog"  "www.google.com/id=6search=dog"
 [7] "www.google.com/id=7search=dog"  "www.google.com/id=8search=dog"  "www.google.com/id=9search=dog"
[10] "www.google.com/id=10search=dog" "www.google.com/id=1search=cat"   ...

Answer 1

您可以在rep或paste0

中添加sprintf来修改代码

 sprintf('%sid=%dsearch=%s', base, id, rep(animal,each=length(id)))

或者

 paste0(base, 'id=',id, 'search=', rep(animal,each=length(id)))

或者@MrFlick建议，我们可以使用expand.grid获取动物＆＃39;之间的所有组合。并且＆＃39; id＆＃39;

  with(expand.grid(a=animal, i=id), paste0(base, "id=", i, "search=", a))

paste0多个不同长度的列表，没有循环

1 个答案: