All, I have the following two data sets:   have1:   ID Date1 67749831 28AUG2015:08:49:00.000000 68011120 10SEP2015:11:03:00.000000   have2:  ID Date2 67749831 26AUG2015:08:49:00.000000 67749831 27AUG2015:08:49:00.000000 67749831 29AUG2015:08:49:00.000000   I want the following dataset:   Want: ID Date1 Date2 67749831 28AUG2015:08:49:00.000000 27AUG2015:08:49:00.000000 68011120 10SEP2015:11:03:00.000000     The idea is to merge the two files based on the exact same ID, but I also want the Date2 to be the latest date that is still before Date1. There might be many Instances of a Date2 that come before Date1 (I want the most recent one), one instance, or no instances.   Does anyone have any ideas?    Thanks! ... View more

Here is my data:   group-var datetime a 09AUG2014:07:52:00 b 17JUL2014:19:32:00 b 30JUL2014:16:15:00 c 12JUL2014:07:02:00 a 12JUL2014:09:41:00 c 15JUL2014:21:23:00 b 14AUG2014:20:52:00 c 15SEP2014:11:32:00 a 22SEP2014:09:14:00 b 01JUL2014:12:27:00 c 03JUL2014:09:33:00 a 03JUL2014:09:04:00 b 12JUL2014:17:58:00 b 28JUL2014:14:37:00 b 04JUL2014:14:56:00 b 26JUL2014:21:32:00 c 30OCT2014:18:42:00 c 06JAN2015:14:47:00 c 30SEP2014:19:18:00 Is there a way to do either of the following:   1) a simple set of histograms, one for each grouped_var, that adds up the number of observations for that group each month? (I would rather not type out each group_var, as there are more than just a,b, and c.)   2) a multiple series line chart that has a separate series for each grouped_var that shows the number of occurences of for each month?   I searched but couldn't find the answer, so thank you so much in advance! ... View more