Hello,
I have a data similar to the one below, but without the max3_value column. This is the one I would like to find, but I do not know how.
max3_value takes the last 3 values of the value column (within a group of person) and finds the maximum value of them. Of course, if it is the first or the second observation, it outputs a missing value.
For example: max3_value=10 in period 3 for person A is calculated as a max(10,5,3).
I thought of transposing the data with lagged values, but still I do not know how calculate it within groups of person.
I would kindly appreciate any help.
person | period | value | max3_value |
A | 1 | 10 | . |
A | 2 | 5 | . |
A | 3 | 3 | 10 |
A | 4 | 5 | 5 |
A | 5 | 2 | 5 |
A | 6 | 3 | 5 |
A | 7 | 4 | 4 |
A | 8 | 14 | 14 |
B | 1 | 6 | . |
B | 2 | 5 | . |
B | 3 | 1 | 6 |
B | 4 | 1 | 4 |
B | 5 | 4 | 4 |
One way is populate variables with the previous 2 values and keep count of how many obs you have seen for this person.
data want;
set have;
by person ;
lag1=lag1(value);
lag2=lag2(value);
if first.person then cnt=0;
cnt + 1;
if cnt < 3 then max3=.;
else max3 = max(lag1,lag2,value);
run;
One way is populate variables with the previous 2 values and keep count of how many obs you have seen for this person.
data want;
set have;
by person ;
lag1=lag1(value);
lag2=lag2(value);
if first.person then cnt=0;
cnt + 1;
if cnt < 3 then max3=.;
else max3 = max(lag1,lag2,value);
run;
Thank you for prompt response, it works perfectly.
Why is it obvious that the first two values will be missing? Do you always want them to be?
Also, why is the next to the last value for person A assigned the value 4? Was that supposed to be 14?
You are right, this is not obvious, but that is the way I want them to be (it makes sense in the original dataset).
max3_value=4 is OK, as it is a max(2,3,4).
Tom's suggested code appears to accomplish what you want.
Actually it should be 5 as the max of 5,1,1 is 5.
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