在R中汇总/重塑数据

Question

对于示例数据框：

df <- structure(list(id = 1:18, region = structure(c(1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("a", 
"b"), class = "factor"), age.cat = structure(c(1L, 1L, 2L, 2L, 
2L, 3L, 3L, 4L, 1L, 1L, 1L, 1L, 2L, 2L, 3L, 4L, 4L, 4L), .Label = c("0-18", 
"19-35", "36-50", "50+"), class = "factor")), .Names = c("id", 
"region", "age.cat"), class = "data.frame", row.names = c(NA, 
-18L))

我想重塑数据，详情如下：

region 0-18 19-35 36-50 50+
a      2    3     2     1
b      4    2     1     3

我只是简单地聚合或重塑数据吗？任何帮助将不胜感激。

Answer 1

您只需使用table：

即可

 table(df$region, df$age.cat)

    0-18 19-35 36-50 50+
  a    2     3     2   1
  b    4     2     1   3

Answer 2

使用reshape2：

install.packages('reshape2')
library(reshape2)

df1 <- melt(df, measure.vars = 'age.cat')
df1 <- dcast(df1, region ~ value)