That's exactly what I was thinking. Thanks tons.
Sent from Yahoo Mail on Android
From:"arun" <smartpink...@yahoo.com>
Date:Sun, Feb 15, 2015 at 2:47 AM
Subject:Re: Difference in dates for unique ID
HI Farnoosh,
Not sure I understand the expected output.� The difference between the first 2
days is "136 days"
May be this helps
� library(data.table)
� � � dcast.data.table(setDT(df)[, list(Visit=.N, Diff=
as.numeric(abs(diff(as.Date(Date, format='%d-%b-%y'))))) ,
� � � � by = ID], ID+Visit~ Diff, value.var='Diff', length)
� � ID Visit 136 255 857
� � 1:� 1� � 2� 1� 0� 0
� � 2:� 2� � 3� 0� 1� 1
On Wednesday, February 11, 2015 5:47 PM, farnoosh sheikhi
<farnoosh...@yahoo.com> wrote:
Hi Arun,
I have a data set that look s like below. I wanted to get a difference in dates
for each unique ID and record it as a new X and have binary input for each one.
ID� Date
1� � � � 06-Sep-13
1� � � � 20-Jan-14
2� � � � 06-Mar-12
2� � � � 25-Jun-11
2� � � � 29-Oct-13
For example for the first two date for ID=1 ( 20-Jan-14 - 06-Sep-13 ~ 121) and
I want the data to be like follow:
ID� Visit� 121
1� � � 2� � � � 1
2� � � 3� � � � 0
I really appreciate if you can help me with this. I know I need to write some
kind of loop, but I don't know how to think of the logic behind it.
Thanks a lot.
Farnoosh
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