R - 按组查找共同元素[重复]

Question

我正在使用以下数据集

library(data.table)
dat <- fread("https://www.dropbox.com/s/kj66h9shv6zge91/mydat.csv?dl=1")

看起来像这样：

            source_id experiment_id variable_id
   1: CESM2-WACCM-FV2    historical          pr
   2: CESM2-WACCM-FV2    historical          pr
   3: CESM2-WACCM-FV2    historical         tas
   4: CESM2-WACCM-FV2    historical         tas
   5:     FGOALS-f3-L    historical          pr
  ---                                          
5657:      MRI-ESM2-0        ssp585          pr
5658:     CESM2-WACCM        ssp585          pr
5659:     CESM2-WACCM        ssp585         tas
5660:     CESM2-WACCM        ssp585         tas
5661:     CESM2-WACCM        ssp585      tasmax

对于每个variable_id，我正在尝试查找source_id 中同时存在于experiment_id 的所有元素中的元素列表（例如“历史”、“ssp126”、“ssp245”、“ssp370 ", "ssp585")。

关于如何到达那里的任何想法？看起来像一个简单的问题，但我在 SO 上找不到适用于字符而不是数值的充分答案。

Answer 1

也许这会有所帮助：

by(dat, dat$variable_id, function(x) 
        Reduce(intersect, split(x$source_id, x$experiment_id)))

#dat$variable_id: pr
# [1] "BCC-CSM2-MR" "MRI-ESM2-0"  "CESM2-WACCM" "INM-CM5-0"  "INM-CM4-8"    
# [6] "MPI-ESM1-2-HR" "CMCC-CM2-SR5"  "NorESM2-MM"  "EC-Earth3"  "EC-Earth3-Veg"
#[11] "GFDL-ESM4"    
#-------------------------------------------------------------------------- 
#dat$variable_id: tas
# [1] "BCC-CSM2-MR"   "MRI-ESM2-0"    "CESM2-WACCM"   "AWI-CM-1-1-MR" "INM-CM4-8"
# [6] "INM-CM5-0"     "MPI-ESM1-2-HR" "CMCC-CM2-SR5"  "NorESM2-MM"    "EC-Earth3"
#[11] "EC-Earth3-Veg" "GFDL-ESM4"    
#-------------------------------------------------------------------------- 
#dat$variable_id: tasmax
# [1] "BCC-CSM2-MR"   "MRI-ESM2-0"    "AWI-CM-1-1-MR" "INM-CM4-8"     "INM-CM5-0"
# [6] "MPI-ESM1-2-HR" "NorESM2-MM"    "EC-Earth3"     "EC-Earth3-Veg" "GFDL-ESM4"
#-------------------------------------------------------------------------- 
#dat$variable_id: tasmin
# [1] "BCC-CSM2-MR"   "MRI-ESM2-0"    "AWI-CM-1-1-MR" "INM-CM4-8"     "INM-CM5-0"
# [6] "MPI-ESM1-2-HR" "NorESM2-MM"    "EC-Earth3"     "EC-Earth3-Veg" "GFDL-ESM4"

对于每个variable_id，这将返回所有experiment_id 中存在的常见source_id。

---

如果您想找出每个variable_id 和每个experiment_id 的共同source_id

Reduce(intersect, split(dat$source_id, list(dat$variable_id, dat$experiment_id)))

#[1] "BCC-CSM2-MR"   "MRI-ESM2-0"    "INM-CM5-0"     "INM-CM4-8"    
#[5] "MPI-ESM1-2-HR" "NorESM2-MM"    "EC-Earth3"     "EC-Earth3-Veg"
#[9] "GFDL-ESM4"