Data.table: कुंजी विराम `द्वारा` कार्यात्मकता

मैं पूरी तरह से निश्चित नहीं हूं कि इसका क्या कारण है, इसलिए यहां सबसे न्यूनतम हम हैं जो मुझे मिल सकते हैं

library(data.table) # Tested on v 1.9.7
dt <-  data.table( origin = c("A", "A", "A", "A", "A", "A", "B", "B", "A", "A", "C", "C", "B", "B", "B", "B", "B", "C", "C", "B", "A", "C", "C", "C", "C", "C", "A", "A", "C", "C", "B", "B"),
                   destination = c("A", "A", "A", "A", "B", "B", "A", "A", "C", "C", "A", "A", "B", "B", "B", "C", "C", "B", "B", "A", "B", "C", "C", "C", "A", "A", "C", "C", "B", "B", "C", "C"),
                   points_in_dest = c(5, 5, 5, 5, 4, 4, 5, 5, 3, 3, 5, 5, 4, 4, 4, 3, 3, 4, 4, 5, 4, 3, 3, 3, 5,5, 3, 3, 4, 4, 3, 3),
                   depart_time = c(7, 8, 16, 18, 7, 8, 16, 18, 7, 8, 16, 18, 7, 8, 16, 7, 8, 16, 18, 8, 16, 7, 8, 18, 7, 8, 16, 18, 7, 8, 16, 18),   
                   travel_time = c(0, 0, 0, 0, 70, 10, 70, 10, 10, 10, 70, 70, 0, 0, 0, 70, 10, 10, 70, 70, 10, 0, 0, 0, 10, 70, 10, 70, 10, 70, 70, 10) )

dt[ depart_time<=8  & travel_time < 60, condition1 := TRUE]
dt[ depart_time>=16 & travel_time < 60, condition2 := TRUE] 

setkey(dt, origin, destination)
res <- unique(dt[(condition1)])[unique(dt[(condition2)]), 
                                on = c(destination = "origin", origin = "destination"), 
                                nomatch = 0L]
res[, .(points = sum(points_in_dest)),  keyby = origin]
#    origin points
#1:      A      5
#2:      A      4
#3:      B      4
#4:      B      3
#5:      C      5
#6:      C      4
#7:      C      3

जैसा कि आप देख सकते हैं, by ने इरादा के अनुसार काम नहीं किया और सभी पंक्तियों को वापस कर दिया गया। यह स्पष्ट रूप से एक कुंजीयन समस्या है क्योंकि निम्नलिखित इसे ठीक करता है:

setattr(res, "sorted", NULL)
res[, .(points = sum(points_in_dest)), keyby = origin]
#    origin points
#1:      A      9
#2:      B      7
#3:      C     12

या, वैकल्पिक रूप से origin को एक कारक के लिए पूर्व-वर्गीकृत करना

res[, .(points = sum(points_in_dest)), keyby = factor(origin)]
#    factor points
#1:      A      9
#2:      B      7
#3:      C     12

यह इस तो सवाल से लिया गया है http://stackoverflow.com/questions/37239649/aggregate-data-table-based-on-condition-in-another-row