R 中时间序列横截面数据中的循环
Loops in Time-Series-Cross-Section Data in R
我现在已经为我的时间序列横截面数据集苦苦挣扎了一段时间，尤其是在试图找到一种方法来为每个国家和年份定义一列的最大值时。我尝试了不同版本的 for 和 if/else 循环，但并没有真正成功。你能帮我找线索吗？
这将是我的数据结构的一个可重现的小例子：
country <- c("a","a","a","a","a","a","b","b","b","b","b","b","c","c","c","c","c","c")
year <- c(2002, 2003, 2004, 2005, 2006, 2007, 2002, 2003, 2004, 2005, 2006, 2007, 2002, 2003, 2004, 2005, 2006, 2007)
topic <-c("u", "v", "w", "x","y","z","u", "v", "w", "x","y","z","u", "v", "w", "x","y","z")
perc <-c(0.3,0.4,0.1,0.2,0,0,0.2,0.3,0.1,0.1,0.1,0.2,0.1,0.2,0.2,0.3,0, 0.2)
dta <- data.frame(country, year, topic, perc)
最后，我想创建一个新变量来说明在给定年份和国家/地区中百分比最高的主题：
topicmax <-c("v","v","v","v","v","v","v","v","v","v","v","v","x","x","x","x","x","x")
最好我还会生成另一个变量，指定具有最高 perc 值的主题的确切百分比。
如有任何帮助，我们将不胜感激。我发现的所有关于循环的教程都没有解决时间序列的横截面问题……谢谢！
解决该问题的一种方法是使用 which.max。它定位最大值的索引位置。该索引可用于子集 topic:
library(data.table)
setDT(dta)[, topicmax := topic[which.max(perc)], by=country]
# country year topic perc topicmax
# 1: a 2002 u 0.3 v
# 2: a 2003 v 0.4 v
# 3: a 2004 w 0.1 v
# 4: a 2005 x 0.2 v
# 5: a 2006 y 0.0 v
# 6: a 2007 z 0.0 v
# 7: b 2002 u 0.2 v
# 8: b 2003 v 0.3 v
# 9: b 2004 w 0.1 v
# 10: b 2005 x 0.1 v
# 11: b 2006 y 0.1 v
# 12: b 2007 z 0.2 v
# 13: c 2002 u 0.1 x
# 14: c 2003 v 0.2 x
# 15: c 2004 w 0.2 x
# 16: c 2005 x 0.3 x
# 17: c 2006 y 0.0 x
# 18: c 2007 z 0.2 x
我现在已经为我的时间序列横截面数据集苦苦挣扎了一段时间，尤其是在试图找到一种方法来为每个国家和年份定义一列的最大值时。我尝试了不同版本的 for 和 if/else 循环，但并没有真正成功。你能帮我找线索吗？
这将是我的数据结构的一个可重现的小例子：
country <- c("a","a","a","a","a","a","b","b","b","b","b","b","c","c","c","c","c","c")
year <- c(2002, 2003, 2004, 2005, 2006, 2007, 2002, 2003, 2004, 2005, 2006, 2007, 2002, 2003, 2004, 2005, 2006, 2007)
topic <-c("u", "v", "w", "x","y","z","u", "v", "w", "x","y","z","u", "v", "w", "x","y","z")
perc <-c(0.3,0.4,0.1,0.2,0,0,0.2,0.3,0.1,0.1,0.1,0.2,0.1,0.2,0.2,0.3,0, 0.2)
dta <- data.frame(country, year, topic, perc)
最后，我想创建一个新变量来说明在给定年份和国家/地区中百分比最高的主题：
topicmax <-c("v","v","v","v","v","v","v","v","v","v","v","v","x","x","x","x","x","x")
最好我还会生成另一个变量，指定具有最高 perc 值的主题的确切百分比。
如有任何帮助，我们将不胜感激。我发现的所有关于循环的教程都没有解决时间序列的横截面问题……谢谢！
解决该问题的一种方法是使用 which.max。它定位最大值的索引位置。该索引可用于子集 topic:
library(data.table)
setDT(dta)[, topicmax := topic[which.max(perc)], by=country]
# country year topic perc topicmax
# 1: a 2002 u 0.3 v
# 2: a 2003 v 0.4 v
# 3: a 2004 w 0.1 v
# 4: a 2005 x 0.2 v
# 5: a 2006 y 0.0 v
# 6: a 2007 z 0.0 v
# 7: b 2002 u 0.2 v
# 8: b 2003 v 0.3 v
# 9: b 2004 w 0.1 v
# 10: b 2005 x 0.1 v
# 11: b 2006 y 0.1 v
# 12: b 2007 z 0.2 v
# 13: c 2002 u 0.1 x
# 14: c 2003 v 0.2 x
# 15: c 2004 w 0.2 x
# 16: c 2005 x 0.3 x
# 17: c 2006 y 0.0 x
# 18: c 2007 z 0.2 x