Question

我的data.frame类似于以下简化版：

ddf
  id                  country          area
1  1 United States of America North America
2  2           United Kingdom        Europe
3  3     United Arab Emirates          Arab
4  4             Saudi Arabia          Arab
5  5                   Brazil South America

ddf = structure(list(id = 1:5, country = c("United States of America", 
"United Kingdom", "United Arab Emirates", "Saudi Arabia", "Brazil"
), area = c("North America", "Europe", "Arab", "Arab", "South America"
)), .Names = c("id", "country", "area"), class = "data.frame", row.names = c(NA, 
-5L))

我想要打印文本＆＃39; america＆＃39; （不区分大小写）来自

任何专栏
列名为＆＃39; area＆＃39;

行数和列数以及列名是可变的，所以我不能使用ddf [，1]等。

我试过以下但不行：

ddf[apply(ddf, 1, function(x) grepl('america',x, ignore.case=T) ),]
   id              country   area
2   2       United Kingdom Europe
3   3 United Arab Emirates   Arab
NA NA                 <NA>   <NA>

Answer 1

这是使用qdap包的方法：

library(qdap)
Search(ddf, "america")

##   id                  country          area
## 1  1 United States of America North America
## 5  5                   Brazil South America

查看源代码，了解有关其工作原理的更多信息。

对于第二个请求......

Search(ddf, "america", "area")

Answer 2

在基地R：

ddf[do.call(mapply,c(any,lapply(ddf,grepl,pattern="america",ignore.case=TRUE))),]

#  id                  country          area
#1  1 United States of America North America
#5  5                   Brazil South America

Answer 3

 hasAm <-  sapply( ddf, grepl, patt="america", ignore.case=TRUE)
 ddf[ rowSums(hasAm) > 0 , ]
  id                  country          area
1  1 United States of America North America
5  5                   Brazil South America

第一个值hasAm只是一个逻辑图像＆＃39;数据帧，第二行通过逻辑索引传递任何存在TRUE的行。

Answer 4

有人建议我取消删除这个答案，所以在这里。

另一种使用mapply

的方式

> m <- mapply(grep, "america", ddf, ignore.case = TRUE)
> ddf[unique(unlist(m)), ]
#   id                  country          area
# 1  1 United States of America North America
# 5  5                   Brazil South America

您也可以同样方式使用lapply和sapply

> s <- sapply(ddf, grep, pattern = "america", ignore.case = TRUE)
> ddf[unique(unlist(s)), ]
#   id                  country          area
# 1  1 United States of America North America
# 5  5                   Brazil South America

在R中搜索data.frame

4 个答案: