r - R中的双循环

Question

我是 R 的新手，对循环有疑问

在我的真实数据集中，有 80 个国家/地区的 15 个部门和 6 类组织的 7000 个观测值，但这里是一个简化的示例。

country <- c("a","a","a","a","a","a","b","b","b","b","b","b",
             "c","c","c","c","c","c","d","d","d","d","d","d")
sector <- c("a","a","a","b","c","c","a","b","b","b","c","c",
            "b","b","b","b","c","c","a","a","b","b","c","c")
organization <-c("a","b","c","c","b","a","a","b","b","c","b","b",
                 "c","a","a","b","b","c","c","b","a","a","b","c")
budget <-c(2,4,3,5,9,7,5,4,3,6,1,2,4,5,6,1,5,3,4,2,3,5,4,6)
table <- data.frame(country, sector, organization, budget)

我想要的是:

1. 特定国家/地区特定部门中不同类型组织的数量。
2. 分配给不同类型组织的部门总预算的百分比。

我首先必须制作一个子集以仅选择来自国家“a”和部门“a”的信息

smalltable <-subset(table, (country == "a") & (sector == "a"))

然后回答我的第一个问题，一个国家的一个部门中每种类型的组织有多少

smalltable$count <- table(smalltable$organization)

然后我需要找到财务的百分比

smalltable$percentage <- smalltable$budget / sum(smalltable$budget)

然后我用了tapply

 N <- tapply(smalltable$count, smalltable$organization, FUN=sum)
 financialshare <- tapply(smalltable$percentage, smalltable$organization, FUN=sum)    

最后结合这个:

 total <- data.frame (smalltable$country,smalltable$sector,smalltable$organization, N,financialshare)
 total

这是我需要的小 table !

但是我的所有 15 个部门和所有 80 个国家/地区都需要这个，所以我需要某种循环功能来运行所有部门的循环并为每个国家/地区重复此循环。 我需要尽可能精简这些表格，将有关 1 个国家(即 15 个部门)的所有信息汇总到一张表格中。还应从表中删除零值以节省空间。

我需要如何进行？

Answer 1

我会给出一个data.table答案

library(data.table)
my_table=data.table(country, sector, organization, budget)
by_org=my_table[, list(count=.N, budget=sum(budget)),
                  keyby=list(country, sector, organization)]
total_budgets=my_table[, list(total_budget=sum(budget)),
                  keyby=list(country, sector)]
joined_table= total_budgets[by_org]
joined_table[,percentage:=budget/total_budget]

来自 Matthew 的编辑:在 v1.8.1 中，按组使用 :=，不需要连接，因此它更容易和更快，并且 total_budget 列被添加到右边比它在 v1.8.0 中使用 join 的地方更自然:

DT = data.table(country, sector, organization, budget) 
ans = DT[, list(count=.N, budget=sum(budget)),
           keyby=list(country, sector, organization)] 
ans[, total_budget:=sum(budget), by=list(country,sector)]
ans[, percentage:=budget/total_budget]

结果(使用 v1.8.1):

    country sector organization count budget total_budget percentage
 1:       a      a            a     1      2            9  0.2222222
 2:       a      a            b     1      4            9  0.4444444
 3:       a      a            c     1      3            9  0.3333333
 4:       a      b            c     1      5            5  1.0000000
 5:       a      c            a     1      7           16  0.4375000
 6:       a      c            b     1      9           16  0.5625000
 7:       b      a            a     1      5            5  1.0000000
 8:       b      b            b     2      7           13  0.5384615
 9:       b      b            c     1      6           13  0.4615385
10:       b      c            b     2      3            3  1.0000000
11:       c      b            a     2     11           16  0.6875000
12:       c      b            b     1      1           16  0.0625000
13:       c      b            c     1      4           16  0.2500000
14:       c      c            b     1      5            8  0.6250000
15:       c      c            c     1      3            8  0.3750000
16:       d      a            b     1      2            6  0.3333333
17:       d      a            c     1      4            6  0.6666667
18:       d      b            a     2      8            8  1.0000000
19:       d      c            b     1      4           10  0.4000000
20:       d      c            c     1      6           10  0.6000000

这里需要注意两点:首先，就计数和总和而言，您的问题有点模糊和矛盾，但希望我的代码片段在我所做的计算方面足够 self 解释。

其次，在 R 中循环大量观察并不是惯用的，因为这往往很慢。大多数使用 R 编程一段时间的人都倾向于使用向量运算、plyr、data.table 或其他类似的包。

但为了完整起见，循环构造如下:

for (item in list)
{
    ...
}

遍历公共(public)索引...

for (i in 1:length(object))
{
    ...
}