How to add new observation to already created dataset in SAS ? For example, if I have dataset 'dataX' with variable 'x' and 'y' and I want to add new observation which is multiplication by two of the
of the observation number n, how can I do it ?
dataX :
x y
1 1
1 21
2 3
I want to create :
dataX :
x y
1 1
1 21
2 3
10 210
where observation number four is multiplication by ten of observation number two.
data X;
input x y;
datalines;
1 1
1 21
2 3
;
run;
data X ;
set X end=eof;
if eof then do;
output;
x=10 ;y=210;
end;
output;
run;
Here is one way to do this:
data dataX;
input x y;
datalines;
1 1
1 21
2 3
run;
/* Create a new observation into temp data set */
data _addRec;
set dataX(firstobs=2); /* Get observation 2 */
x = x * 10; /* Multiply each by 10 */
y = y * 10;
output; /* Output new observation */
stop;
run;
/* Add new obs to original data set */
proc append base=dataX data=_addRec;
run;
/* Delete the temp data set (to be safe) */
proc delete data=_addRec;
run;
data a ;
do kk=1 to 5 ;
output ;
end ;
run;
data a2 ;
kk=999 ;
output ;
run;
data a; set a a2 ;run ;
proc print data=a ;run ;
Result:
The SAS System 1
OBS kk
1 1
2 2
3 3
4 4
5 5
6 999
You can use macro to obtain your desired result :
Write a macro which will read first DataSet and when _n_=2 it will multiply x and y with 10.
After that create another DataSet which will hold only your muliplied value let say x'=10x and y'=10y.
Pass both DataSet in another macro which will set the original datset and newly created dataset.
Logic is you have to create another dataset with value 10x and 10y and after that set wih previous dataset.
I hope this will help !
Related
I don't know how to describe this question but here is an example. I have an initial dataset looks like this:
input first second $3.;
cards;
1 A
1 B
1 C
1 D
2 E
2 F
3 S
3 A
4 C
5 Y
6 II
6 UU
6 OO
6 N
7 G
7 H
...
;
I want an output dataset like this:
input first second $;
cards;
1 "A,B,C,D"
2 "E,F"
3 "S,A"
4 "C"
5 "Y"
6 "II,UU,OO,N"
7 "G,H"
...
;
Both tables will have two columns. Unique value of range of the column "first" could be 1 to any number.
Can someone help me ?
something like below
proc sort data=have;
by first second;
run;
data want(rename=(b=second));
length new_second $50.;
do until(last.first);
set have;
by first second ;
new_second =catx(',', new_second, second);
b=quote(strip(new_second));
end;
drop second new_second;
run;
output is
first second
1 "A,B,C,D"
2 "E,F"
3 "A,S"
4 "C"
5 "Y"
6 "II,N,OO,UU"
7 "G,H"
You can use by-group processing and the retain function to achieve this.
Create a sample dataset:
data have;
input id value $3.;
cards;
1 A
1 B
1 C
1 D
2 E
2 F
3 S
3 A
4 C
5 Y
6 II
6 UU
6 OO
6 N
7 G
7 H
;
run;
First ensure that your dataset is sorted by your id variable:
proc sort data=have;
by id;
run;
Then use the first. and last. notation to identify when the id variable is changing or about to change. The retain statement tells the datastep to keep the value within concatenated_value over observations rather than resetting it to a blank value. Use the quote() function to apply the " chars around the result before outputting the record. Use the cats() function to perform the actual concatenation and separate the records with a ,.
data want;
length contatenated_value $500.;
set have;
by id;
retain contatenated_value ;
if first.id then do;
contatenated_value = '';
end;
contatenated_value = catx(',', contatenated_value, value);
if last.id then do;
contatenated_value = quote(cats(contatenated_value));
output;
end;
drop value;
run;
Output:
contatenated_
value id
"A,B,C,D" 1
"E,F" 2
"S,A" 3
"C" 4
"Y" 5
"II,UU,OO,N" 6
"G,H" 7
I want to output the last value of a variable pr. sub-group to a SAS dataset, preferably in just a few steps. The code below do it, but I was hoping to do it in one step a la by variable; if last.variable then output; as for the case with just 1 by-variable.
data two;
input year firm price;
cards;
1 1 48
1 1 45
2 2 50
1 2 42
2 1 41
2 2 51
2 1 52
1 1 43
1 2 52;
run;
proc sort data = two;by year firm;run;
/* a) Create id across both sub-groups */
data two1;
set two;
by year firm;
retain case_id;
if FIRST.year OR first.firm then case_id + 1;
run;
/* b) Use id to output last values across both by-groups */
data two2;
set two1;
by case_id;
if last.case_id then output;
run;
proc print data = two1;run;
proc print data = two2;run;
With just 1 by-variable the two steps marked a) and b) can be combined. Is it possible with more than one by-group?
In data step a) add condition if lst.firm then output two2.
The final code should looks like:
data two1 two2;
set two;
by year firm;
retain case_id;
if FIRST.year OR first.firm then case_id + 1;
if last.firm then output two2;
output two1;
run;
how can i perform calculation for the last n observation in a data set
For example if I have 10 observations I would like to create a variable that would sum the last 5 values of another variable. Please do not suggest that I lag 5 times or use module ( N ). I need a bit more elegant solution than that.
with the code below alpha is the data set that i have and bravo is the one i need.
data alpha;
input lima ## ;
cards ;
3 1 4 21 3 3 2 4 2 5
;
run ;
data bravo;
input lima juliet;
cards;
3 .
1 .
4 .
21 .
3 32
3 32
2 33
4 33
2 14
5 16
;
run;
thank you in advance!
You can do this in the data step or using PROC EXPAND from SAS/ETS if available.
For the data step the idea is that you start with a cumulative sum (summ), but keep track of the number of values that were added so far (ninsum). Once that reaches 5, you start outputting the cumulative sum to the target variable (juliet), and from the next step you start subtracting the lagged-5 value to only store the sum of the last five values.
data beta;
set alpha;
retain summ ninsum 0;
summ + lima;
ninsum + 1;
l5 = lag5(lima);
if ninsum = 6 then do;
summ = summ - l5;
ninsum = ninsum - 1;
end;
if ninsum = 5 then do;
juliet = summ;
end;
run;
proc print data=beta;
run;
However there is a procedure that can do all kind of cumulative, moving window, etc calculations: PROC EXPAND, in which this is really just one line. We just tell it to calculate the backward moving sum in a window of width 5 and set the first 4 observations to missing (by default it will expand your series by 0's on the left).
proc expand data=alpha out=gamma;
convert lima = juliet / transformout=(movsum 5 trimleft 4);
run;
proc print data=gamma;
run;
Edit
If you want to do more complicated calculations, you need to carry the previous values in retained variables. I thought you wanted to avoid that, but here it is:
data epsilon;
set alpha;
array lags {5};
retain lags1 - lags5;
/* do whatever calculation is needed */
juliet = 0;
do i=1 to 5;
juliet = juliet + lags{i};
end;
output;
/* shift over lagged values, and add self at the beginning */
do i=5 to 2 by -1;
lags{i} = lags{i-1};
end;
lags{1} = lima;
drop i;
run;
proc print data=epsilon;
run;
I can offer rather ugly solution:
run data step and add increasing number to each group.
run sql step and add column of max(group).
run another data step and check if value from (2)-(1) is less than 5. If so, assign to _num_to_sum_ variable (for example) the value that you want to sum, otherwise leave it blank or assign 0.
and last do a sql step with sum(_num_to_sum_) and group results by grouping variable from (1).
EDIT: I have added a live example of the concept in a bit more compacted way.
input var1 $ var2;
cards;
aaa 3
aaa 5
aaa 7
aaa 1
aaa 11
aaa 8
aaa 6
bbb 3
bbb 2
bbb 4
bbb 6
;
run;
data step1;
set sourcetable;
by var1;
retain obs 0;
if first.var1 then obs = 0;
else obs = obs+1;
if obs >=5 then to_sum = var2;
run;
proc sql;
create table rezults as
select distinct var1, sum(to_sum) as needed_summs
from step1
group by var1;
quit;
In case anyone reads this :)
I solved it the way I needed it to be solved. Although now I am more curious which of the two(the retain and my solution) is more optimal in terms of computing/processing time.
Here is my solution:
data bravo(keep = var1 summ);
set alpha;
do i=_n_ to _n_-4 by -1;
set alpha(rename=var1=var2) point=i;
summ=sum(summ,var2);
end;
run;
Suppose a data are as follows:
A B C
1 3 2
1 4 9
2 6 0
2 7 3
where A B and C are the variable names.
Is there a way to transform the table to
A 1
A 1
A 2
A 2
B 3
B 4
B 6
B 7
C 2
C 9
C 0
C 3
Expanding on the advice from #donPablo, here's how you would code it. Create an array to read across the data, then output each iteration of that array so you end up with the number of rows being the rows * columns from the original dataset. The VNAME function enables you to store the variable name (A, B, C) as a value in a separate variable.
data have;
input A B C;
datalines;
1 3 2
1 4 9
2 6 0
2 7 3
;
run;
data want;
set have;
length var1 $10;
array vars{*} _numeric_;
do i=1 to dim(vars);
var1=vname(vars{i});
var2=vars{i};
keep var1 var2;
output;
end;
run;
proc sort data=want;
by var1;
run;
The least amount of (expensive) development time might be --
Read and store the first row
For each subsequent row
Read the row
Create three records
Until end
Sort
How many times will this be run? Per day/ per year?
What number of rows are there?
Might we save 1 hr / month? 1 min / year? Something will need to read the entire file. Optomize last. Make it work first.
tkx
It should work correctly:
DATA A(keep A);
new_var = 'A';
SET your_data;
RUN;
DATA B(keep B);
new_var = 'B';
SET your_data;
RUN;
DATA C(keep C);
new_var = 'C';
SET your_data;
RUN;
PROC APPEND base=A data=B FORCE;
RUN;
PROC APPEND base=A data=C FORCE;
RUN;
Data A is a result data set.
In this data step I do not understand what if last.y do...
Could you tell me ?
data stop2;
set stop2;
by x y z t;
if last.y; /*WHAT DOES THIS DO ??*/
if t ne 999999 then
t=t+1;
else do;
t=0;
z=z+1;
end;
run;
LAST.Y refers to the row immediately before a change in the value of Y. So, in the following dataset:
data have;
input x y z;
datalines
1 1 1
1 1 2
1 1 3
1 2 1
1 2 2
1 2 3
1 3 1
1 3 2
1 3 3
2 3 1
2 3 2
2 3 3
;;;;
run;
LAST.Y would occur on the third, sixth, ninth, and twelfth rows in that dataset (on each row where Z=3). The first two times are when Y is about to change from 1 to 2, and when it is about to change from 2 to 3. The third time is when X is about to change - LAST.Y triggers when Y is about to change or when any variable before it in the BY list changes. Finally, the last row in the dataset is always LAST.(whatever).
In the specific dataset above, the subsetting if means you only take the last row for each group of Ys. In this code:
data want;
set have;
by x y z;
if last.y;
run;
You would end up with the following dataset:
data want;
input x y z;
datalines;
1 1 3
1 2 3
1 3 3
2 3 3
;;;;
run;
at the end.
One thing you can do if you want to see how FIRST and LAST operate is to use PUT _ALL_;. For example:
data want;
set have;
by x y z;
put _all_;
if last.y;
run;
It will show you all of the variables, including FIRST.(whatever) and LAST.(whatever) on the dataset. (FIRST.Y and LAST.Y are actually variables.)
In SAS, first. and last. are variables created implicitly within a data step.
Each variable will have a first. and a last. corresponding to each record in the DATA step. These values will be wither 0 or 1. last.y is same as saying if last.y = 1.
Please refer here for further info.
That is an example of subsetting IF statement. Which is different than an IF/THEN statement. It basically means that if the condition is not true then stop this iteration of the data step right now.
So
if last.y;
is equivalent to
if not last.y then delete;
or
if not last.y then return;
or
if last.y then do;
... rest of the data step before the run ...
end;