topic Re: SAS Code to calculate difference (in days) between last and second-last date in SAS Programming

SAS Code to calculate difference (in days) between last and second-last date

HansSteenhuis — Wed, 21 Feb 2018 18:35:09 GMT

Hello,

Example of data:

ID Date amount_of_days

1 01-01-2017

1 04-01-2017

1 12-01-2017 12

2 01-04-2017

2 01-05-2017 31

3 01-02-2018

3 05-02-2018

3 11-02-2018

3 21-02-2018 10

is it possible to calculate the amount of days between the last and second-last date within the ID?

Thank you very much for any comments.

Re: SAS Code to calculate difference (in days) between last and second-last date

Astounding — Wed, 21 Feb 2018 18:42:22 GMT

Your dates have to be actual SAS dates, not character strings. As long as your data is in order by ID:

data want;

set have;

by id;

amount_of_days = dif(date);

if last.id=0 or first.id=1 then amount_of_days = .;

run;

Re: SAS Code to calculate difference (in days) between last and second-last date

HansSteenhuis — Wed, 21 Feb 2018 19:01:36 GMT

thank you very much, it works 🙂

Is is also possible to calculate the amount of days like this Example:

Example of data:

ID Date number_of_days

1 01-01-2017 0

1 04-01-2017 4

1 12-01-2017 9

2 01-04-2017 0

2 01-05-2017 2

3 01-02-2018 276

3 05-02-2018 5

3 11-02-2018 7

3 21-02-2018 11

Re: SAS Code to calculate difference (in days) between last and second-last date

Reeza — Wed, 21 Feb 2018 19:04:08 GMT

Use the DIF() function and then set it to 0 at the first of each group using FIRST.

@HansSteenhuis wrote:

thank you very much, it works 🙂

Is is also possible to calculate the amount of days like this Example:

Example of data:

ID        Date                            number_of_days

1          01-01-2017                 0

1          04-01-2017                 4

1         12-01-2017 9

2         01-04-2017                 0

2         01-05-2017                 2

3          01-02-2018                 276

3          05-02-2018                 5

3          11-02-2018                 7

3          21-02-2018                 11

Re: SAS Code to calculate difference (in days) between last and second-last date

Astounding — Wed, 21 Feb 2018 19:11:29 GMT

Well, your formula is not consistent. Do you want to count both the first and last day in the total number of days? At any rate, you can certainly do this:

data want;

set have;

by id;

amount_of_days = dif(date);

if first.id=1 then amount_of_days = 0;

run;

But it's not clear from your example if you want to use:

amount_of_days = dif(date) + 1;

Test the formulas, to see which one is right for you.

Re: SAS Code to calculate difference (in days) between last and second-last date

HansSteenhuis — Wed, 21 Feb 2018 19:16:46 GMT

Thanks you. I now also use this code for the calculation

data want;
set have;
by id;
amount_of_days = dif(date);
if first.id=1 then amount_of_days = 0;
run;

Re: SAS Code to calculate difference (in days) between last and second-last date

HansSteenhuis — Wed, 21 Feb 2018 19:18:02 GMT

Thank you. I also use this code for the calculation

data want;
set have;
by id;
amount_of_days = dif(date);
if last.id=0 or first.id=1 then amount_of_days = .;
run;