如何从面板/纵向数据中选择一年以图表形式显示？

如何解决如何从面板/纵向数据中选择一年以图表形式显示？

我为167个国家/地区以及2009-2017年提供了以下数据集。 head（df）如下：

area_code year   area_name   area_group Executive Constraints Government Effectiveness Government Integrity
1       AFG 2009 Afghanistan Asia-Pacific              5.940404                 5.601888             5.817723
2       AFG 2010 Afghanistan Asia-Pacific              5.940404                 5.614891             5.817723
3       AFG 2011 Afghanistan Asia-Pacific              5.940404                 4.164573             6.077723
4       AFG 2012 Afghanistan Asia-Pacific              5.940404                 4.171181             6.077723
5       AFG 2013 Afghanistan Asia-Pacific              5.940404                 4.265419             6.837723
6       AFG 2014 Afghanistan Asia-Pacific              5.940404                 4.238977             6.837723
  Political Accountability Regulatory Quality Rule of Law Contract Enforcement Investor Protection
1                 3.852381           4.622449    5.684202             4.211907            4.514932
2                 3.495238           4.582903    5.684202             4.211907            4.514932
3                 3.495238           4.688990    5.684202             4.211907            4.612633
4                 3.495238           4.683196    5.684202             4.211907            4.641368
5                 3.495238           4.943797    5.684202             4.211907            4.635621
6                 4.780952           4.943783    5.684202             4.211907            4.641368
  Property Rights  Val.Avg   HDI     LE                   Subject Descriptor          Units Scale
1        8.746632 5.443613 0.453 60.484 General government total expenditure Percent of GDP    NA
2        9.032347 5.432727 0.463 61.028 General government total expenditure Percent of GDP    NA
3        8.937204 5.312542 0.471 61.553 General government total expenditure Percent of GDP    NA
4        8.937204 5.315825 0.482 62.054 General government total expenditure Percent of GDP    NA
5        8.937204 5.439057 0.487 62.525 General government total expenditure Percent of GDP    NA
6        8.937204 5.579613 0.491 62.966 General government total expenditure Percent of GDP    NA
                                              Country/Series-specific Notes Estimates Start After
1 See notes for:  General government total expenditure (National currency).                  2018
2 See notes for:  General government total expenditure (National currency).                  2018
3 See notes for:  General government total expenditure (National currency).                  2018
4 See notes for:  General government total expenditure (National currency).                  2018
5 See notes for:  General government total expenditure (National currency).                  2018
6 See notes for:  General government total expenditure (National currency).                  2018
             e_p_GDP
1              21.17
2 20.800999999999998
3 21.937000000000001
4 25.027999999999999
5             24.977
6 25.402000000000001

我想知道如何仅绘制给定年份或国家的数据？ 例如。在2009年至2017年期间某个国家（例如阿富汗）的某个变量（例如HDI）的散点图，或在一年中（例如2017年）所有国家的一些变量的散点图。

这是dput（head（df））：

structure(list(area_code = c("AFG","AFG","AFG"),year = c("2009","2010","2011","2012","2013","2014"
),area_name = c("Afghanistan","Afghanistan","Afghanistan"),area_group = c("Asia-Pacific","Asia-Pacific","Asia-Pacific"),`Executive Constraints` = c(5.9404040404,5.9404040404,5.9404040404),`Government Effectiveness` = c(5.6018883995,5.6148910662,4.164573318,4.171181318,4.2654191847,4.238976518
),`Government Integrity` = c(5.8177230501,5.8177230501,6.0777230501,6.8377230501,6.8377230501),`Political Accountability` = c(3.8523809524,3.4952380952,4.780952381
),`Regulatory Quality` = c(4.6224485009,4.5829025009,4.6889900009,4.6831962509,4.9437972509,4.9437830009),`Rule of Law` = c(5.684202383,5.684202383,5.684202383
),`Contract Enforcement` = c(4.2119071093,4.2119071093,4.2119071093),`Investor Protection` = c(4.5149315168,4.5149315168,4.6126326662,4.6413682984,4.6356211719,4.6413682984
),`Property Rights` = c(8.7466324809,9.0323467666,8.9372039095,8.9372039095),Val.Avg = c(5.44361315925556,5.43272739205556,5.31254161917778,5.31582493942222,5.439057355,5.57961341006667),HDI = c(0.453,0.463,0.471,0.482,0.487,0.491),LE = c(60.484,61.028,61.553,62.054,62.525,62.966
),`Subject Descriptor` = c("General government total expenditure","General government total expenditure","General government total expenditure"),Units = c("Percent of GDP","Percent of GDP","Percent of GDP"),Scale = c(NA,NA,NA),`Country/Series-specific Notes` = c("See notes for:  General government total expenditure (National currency).","See notes for:  General government total expenditure (National currency).","See notes for:  General government total expenditure (National currency)."
),`Estimates Start After` = c(2018,2018,2018),e_p_GDP = c("21.17","20.800999999999998","21.937000000000001","25.027999999999999","24.977","25.402000000000001")),row.names = c(NA,6L),class = "data.frame")

解决方法

选择要绘制的数据子集

ggplot(subset(df,year==2019 & area_name=="Denmark"),aes(HDI,LE)) + 
geom_point()

或全部绘制：

ggplot(df,LE)) + 
geom_point() +
facet_grid(year~area_name)