我有下表:-
data <- data.table(alpha = c(rep(letters[1:5], each=4), "f", "f", "g", "h", "h", rep("i", 4)),
year = c(rep(2014:2017, 5), 2014, 2015, 2016, 2015, 2016, 2014:2017),
values = runif(29))
data
# alpha year values
# 1: a 2014 0.58602291
# 2: a 2015 0.84320915
# 3: a 2016 0.15504613
# 4: a 2017 0.81064753
# 5: b 2014 0.89886539
# 6: b 2015 0.81288998
# 7: b 2016 0.92019694
# 8: b 2017 0.64171626
# 9: c 2014 0.07585062
#10: c 2015 0.90201830
#11: c 2016 0.68783471
#12: c 2017 0.80405486
#13: d 2014 0.45197629
#14: d 2015 0.84657377
#15: d 2016 0.25700501
#16: d 2017 0.44786659
#17: e 2014 0.73255596
#18: e 2015 0.45027413
#19: e 2016 0.52385583
#20: e 2017 0.62541879
#21: f 2014 0.38690750
#22: f 2015 0.43807544
#23: g 2016 0.47070025
#24: h 2015 0.57167596
#25: h 2016 0.40591139
#26: i 2014 0.16081680
#27: i 2015 0.71446476
#28: i 2016 0.70543309
#29: i 2017 0.57190553
我想要做的是删除那些多年来没有值的alpha组，即从2014年到2017年。
生成的 data.table 仅包含 a、b、d、e 和 i 组行。因此，它看起来像下面的data.table:-
# alpha year values
# 1: a 2014 0.58602291
# 2: a 2015 0.84320915
# 3: a 2016 0.15504613
# 4: a 2017 0.81064753
# 5: b 2014 0.89886539
# 6: b 2015 0.81288998
# 7: b 2016 0.92019694
# 8: b 2017 0.64171626
# 9: c 2014 0.07585062
#10: c 2015 0.90201830
#11: c 2016 0.68783471
#12: c 2017 0.80405486
#13: d 2014 0.45197629
#14: d 2015 0.84657377
#15: d 2016 0.25700501
#16: d 2017 0.44786659
#17: e 2014 0.73255596
#18: e 2015 0.45027413
#19: e 2016 0.52385583
#20: e 2017 0.62541879
#21: i 2014 0.16081680
#22: i 2015 0.71446476
#23: i 2016 0.70543309
#24: i 2017 0.57190553
最佳答案
我们可以使用 all 和按“alpha”分组的 %in%，并提取序列 (.I) 进行子集
library(data.table)
data[data[, .I[all(2014:2017 %in% year)], by = alpha]$V1]
-输出
alpha year values
<char> <num> <num>
1: a 2014 0.07179522
2: a 2015 0.75057740
3: a 2016 0.93851481
4: a 2017 0.46446911
5: b 2014 0.09386143
6: b 2015 0.83745829
7: b 2016 0.45925816
8: b 2017 0.79701217
9: c 2014 0.52311675
10: c 2015 0.68618138
11: c 2016 0.98856152
12: c 2017 0.54151560
13: d 2014 0.10919439
14: d 2015 0.86810873
15: d 2016 0.07182192
16: d 2017 0.38575802
17: e 2014 0.88276318
18: e 2015 0.01134039
19: e 2016 0.99038433
20: e 2017 0.59897147
21: i 2014 0.07223494
22: i 2015 0.79560440
23: i 2016 0.05423041
24: i 2017 0.24912163
关于r - 删除那些没有指定年份值的行组，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/71387037/