问题
I have input table having more than 750 K raws. It has a field called quarter. I want to create sample such that I get 10% records from each quarter. Main attributes of the data.frame are:
- "SERIAL_NBR"
- "MODELNO"
- "War.Start.Monthly"
"Start.Qua.Yr" is the field where quarter is mentioned. Is there any way through which I can generate sample data which has data(10% of record) for each quarter?
Using sample function I can get sample regardless of the quarter. Code for the same will be:
raw_claim_input[sample(1:nrow(raw_claim_input),as.integer(nrow(raw_claim_input)/10)),]
When I am doing following for one quarter I am not getting expected results as there a logical problem while considering values
raw_claim_input[sample(1:nrow(raw_claim_input[raw_claim_input$War.Start.Monthly=="08-M2",]),as.integer(nrow(raw_claim_input[raw_claim_input$War.Start.Monthly=="08-M2",])/10)),]
The value 08-M2 is the filter, I want to do it for all the values available. There are 70 values for War.Start.Monthly, and I want to generate sample for each value of War.Start.Monthly.
Part of data
Day.Covered SHIP_DATE Warranty.Start.Qua.Yr War.Start.Monthly AssemblyDateUpdated Warranty.End.Date Warranty.End.Qur.Yr War.End.Monthly
252754 365 06-04-2008 00:00 08-Q2 08-M6 06-03-2008 00:00 08-04-2064 64-Q2 64-M4
441605 1095 08-17-2010 11:13:07 10-Q3 10-M8 08-16-2010 12:09:57 08-04-2064 64-Q2 64-M4
583636 731 10-17-2012 00:00:00 12-Q4 12-M10 10-16-2012 00:00:00 08-04-2064 64-Q2 64-M4
115586 731 01-04-2013 00:00 13-Q1 13-M1 01-03-2013 00:00 08-04-2064 64-Q2 64-M4
334221 1095 06-13-2011 12:29:23 11-Q2 11-M6 06-11-2011 11:25 08-04-2064 64-Q2 64-M4
146656 1095 03-16-2011 10:54:37 11-Q1 11-M3 03-15-2011 08:14:40 08-04-2064 64-Q2 64-M4
249956 1095 06-18-2008 12:35:06 08-Q2 08-M6 06-06-2008 10:51 08-04-2064 64-Q2 64-M4
276295 731 05-18-2011 00:00:00 11-Q2 11-M5 05-18-2011 00:00:00 19-11-2014 14-Q4 14-M11
582423 731 10-22-2012 00:00:00 12-Q4 12-M10 10-22-2012 00:00:00 08-04-2064 64-Q2 64-M4
380369 730 08-04-2009 17:43 09-Q3 09-M7 07-31-2009 07:14:17 18-01-2012 12-Q1 12-M1
Please let me know if more details needed.
回答1:
This will do:
X <- read.csv(text="Day.Covered,SHIP_DATE,Warranty.Start.Qua.Yr,War.Start.Monthly,AssemblyDateUpdated,Warranty.End.Date,Warranty.End.Qur.Yr,War.End.Monthly
365, 06-04-2008 00:00, 08-Q2, 08-M6, 06-03-2008 00:00, 08-04-2064 ,64-Q2, 64-M4
1095, 08-17-2010 11:13:07, 10-Q3, 10-M8, 08-16-2010 12:09:57, 08-04-2064 ,64-Q2, 64-M4
731, 10-17-2012 00:00:00, 12-Q4, 12-M10, 10-16-2012 00:00:00, 08-04-2064 ,64-Q2, 64-M4
731, 01-04-2013 00:00, 13-Q1, 13-M1, 01-03-2013 00:00, 08-04-2064 ,64-Q2, 64-M4
1095, 06-13-2011 12:29:23, 11-Q2, 11-M6, 06-11-2011 11:25, 08-04-2064 ,64-Q2, 64-M4
1095, 03-16-2011 10:54:37, 11-Q1, 11-M3, 03-15-2011 08:14:40, 08-04-2064 ,64-Q2, 64-M4
1095, 06-18-2008 12:35:06, 08-Q2, 08-M6, 06-06-2008 10:51, 08-04-2064 ,64-Q2, 64-M4
731, 05-18-2011 00:00:00, 11-Q2, 11-M5, 05-18-2011 00:00:00, 19-11-2014 ,14-Q4, 14-M11
731, 10-22-2012 00:00:00, 12-Q4, 12-M10, 10-22-2012 00:00:00, 08-04-2064 ,64-Q2, 64-M4
730, 08-04-2009 17:43, 09-Q3, 09-M7, 07-31-2009 07:14:17, 18-01-2012 ,12-Q1, 12-M")
# Replicate X to have enough data for this example.
X <- X[rep(seq(nrow(X)), 100),]
# Partition the data according to quarter.
partitions <- split(X, X$Warranty.Start.Qua.Yr)
# Draw samples from each partition.
samples <- lapply(partitions, function(p) p[sample(nrow(p), nrow(p)/10),])
来源：https://stackoverflow.com/questions/19657679/creating-sets-of-samples-from-given-dataframe-using-condition-r