Calculate percentile column from a numeric column - sas

I am trying to create a calculated column called percentile_Idle_Time(I am trying to calculate percentile for every value). The column is percentile value from idle_time% column.
So, the input data is
Total Time Idle Time Idle Time %
5:10:00 0:14:00 4.6%
3:09:00 0:20:00 9.49%
. . .
. . .
So, I am trying to create a new column called percentile_Idle_Time which is nothing but the percentile position of the Idle Time % value
So, the output data should be like
Total Time Idle Time Idle Time % percentile_Idle_Time
5:10:00 0:14:00 4.6% 75.4
3:09:00 0:20:00 9.49% 97.9
. . . .
. . . .
Note: The numbers are pretty rough(not accurate)
I tried using
proc univariate data=WORK.QUERY_FOR_PEOPLENET_DATA_00_0000 noprint;
by DriverId;
var 'Short Idle Time %'n;
output pctlpre=P_ ;
run;
But its not working. The other challenge is to take percentile score from the % column

Do it manually then. Sort the data ascending and use the NOBS to get the number of observations. Use n to divide by NOBS to get the total value.
proc sort data=sashelp.class out=class;
by weight;
run;
data want;
set class Nobs=myobs;
percentile = _n_ / myobs;
run;
NOTE that this does not deal with ties. If you do have ties that need to be dealt with, use PROC RANK instead. I usually do it with a group of 100 and then you'll get the 1 to 100 groups. But its' 96.5 percentile if that's what you're looking for.
proc rank data=sashelp.class out=ranked_class groups=100;
var weight;
ranks weight_percentile;
run;
EDIT: Fixed references in data step and sort to align.

Related

Sum a number of specific rows before and after

I want to do a sum of 250 previous rows for each row, starting from the row 250th.
X= lag1(VWRETD)+ lag2(VWRETD)+ ... +lag250(VWRETD)
X = sum ( lag1(VWRETD), lag2(VWRETD), ... ,lag250(VWRETD) )
I try to use lag function, but it does not work for too many lags.
I also want to calculate sum of 250 next rows after each row.
What you're looking for is a moving sum both forwards and backwards where the sum is missing until that 250th observation. The easiest way to do this is with PROC EXPAND.
Sample data:
data have;
do MKDate = '01JAN1993'd to '31DEC2000'd;
VWRET = rand('uniform');
output;
end;
format MKDate mmddyy10.;
run;
Code:
proc expand data=have out=want;
id MKDate;
convert VWRET = x_backwards_250 / transform=(movsum 250 trimleft 250);
convert VWRET = x_forwards_250 / transform=(reverse movsum 250 trimleft 250 reverse);
run;
Here's what the transformation operations are doing:
Creating a backwards moving sum of 250 observations, then setting the initial 250 to missing.
Reversing VWRET, creating a moving sum of 250 observations, setting the initial 250 to missing, then reversing it again. This effectively creates a forward moving sum.
The key is how to read observations from previous and post rows. As for your sum(n1, n2,...,nx) function, you can replace it with iterative summation.
This example uses multiple set skill to achieve summing a variable from 25 previous and post rows:
data test;
set sashelp.air nobs=nobs;
if 25<_n_<nobs-25+1 then do;
do i=_n_-25 to _n_-1;
set sashelp.air(keep=air rename=air=pre_air) point=i;
sum_pre=sum(sum_pre,pre_air);
end;
do j=_n_+1 to _n_+25;
set sashelp.air(keep=air rename=air=post_air) point=j;
sum_post=sum(sum_post,post_air);
end;
end;
drop pre_air post_air;
run;
Only 26th to nobs-25th rows will be calculated, where nobs stands for number of observations of the setting data sashelp.air.
Multiple set may take long time when meeting big dataset, if you want to be more effective, you can use array and DOW-loop to instead multiple set skill:
data test;
array _val_[1024]_temporary_;
if _n_=1 then do i=1 by 1 until(eof);
set sashelp.air end=eof;
_val_[i]=air;
end;
set sashelp.air nobs=nobs;
if 25<_n_<nobs-25+1 then do;
do i=_n_-25 to _n_-1;
sum_pre=sum(sum_pre,_val_[i]);
end;
do j=_n_+1 to _n_+25;
sum_post=sum(sum_post,_val_[j]);
end;
end;
drop i j;
run;
The weakness is you have to give a dimension number to array, it should be equal or great than nobs.
These skills are from a concept called "Table Look-Up", For SAS context, read "Table Look-Up by Direct Addressing: Key-Indexing -- Bitmapping -- Hashing", Paul Dorfman, SUGI 26.
You don't want use normal arithmetic with missing values becasue then the result is always a missing value. Use the SUM() function instead.
You don't need to spell out all of the lags. Just keep a normal running sum but add the wrinkle of removing the last one in by subtraction. So your equation only needs to reference the one lagged value.
Here is a simple example using running sum of 5 using SASHELP.CLASS data as an example:
%let n=5 ;
data step1;
set sashelp.class(keep=name age);
retain running_sum ;
running_sum=sum(running_sum,age,-(sum(0,lag&n.(age))));
if _n_ >= &n then want=running_sum;
run;
So the sum of the first 5 observations is 68. But for the next observation the sum goes down to 66 since the age on the 6th observation is 2 less than the age on the first observation.
To calculate the other variable sort the dataset in descending order and use the same logic to make another variable.

How to determine the frequency of a time series?

For an if-query I would like to create a macro varibale giving the respective frequency of the underlying time
series. I tried to get some descriptive statistics from proc time series. However, they unfortunately do not include the figure for the frequency.
The underlying times series does not necessarily conclude all periods of the frequency. That excludes a selected count by proc sql from my point of view.
Does anyone know an efficient procedure to determine the frequency without computing the frequency on my own (in a data step or a proc sql code)?
You can use the outspectra statement to help learn what kind of seasonality it has. Based on the data, give PROC TIMESERIES your best guess of day, month, etc. In the example below, we know we want to forecast by month but we do not know what seasonality it has.
proc timeseries data=sashelp.air outspectra=spectra;
id date interval=month;
var air;
run;
Plot this spectra dataset in proc sgplot and you'll see something that looks like this:
proc sgplot data=spectra;
where NOT missing(period);
series x=period y=p;
run;
This line will naturally increase over time, but we're looking for a bumps in the line. Notice the large bump somewhere between 0 and 24 months and the several smaller bumps before it. Let's zoom in on that by filtering out the longer periods.
proc sgplot data=spectra;
where period < 24 and NOT missing(period);
series x=period y=p;
run;
It's pretty clear that there is a strong seasonality of 12, with potentially smaller cycles at 3 and 6 months. From this plot, we can conclude that our seasonality should be 12 based on our spectra plot.
You can turn this into a macro to help identify the season if you'd like. Simply search for the largest bump within a reasonable timeframe. In our case we'll choose 36 because we do not suspect that we have any seasonality > 36 months.
proc sort data=spectra;
by period;
run;
data identify_period;
set spectra;
by period;
where NOT missing(period) AND period LE 36;
delta = abs(p - lag(p) );
run;
proc sql;
select period, max(delta) as max_delta
from identify_period
having delta = max(delta)
;
quit;
Output:
PERIOD max_delta
12 163712
I don't know how to do this without data step logic, but you could wrap the data step in a macro as follows:
%macro get_frequency(data,date_variable,output_variable);
proc sort data=&data (keep=&date_variable) out=__tempsorted;
by &date_variable;
run;
data _null_;
set __tempsorted end=lastobs;
prevdate=lag(&date_variable);
if _n_ > 1 then do;
interval_number+1;
interval_total + (&date_variable - prevdate);
end;
if lastobs then do;
average_interval = interval_total/interval_number;
frequency = round(365.25/average_interval);
call symput ("&output_variable",left(put(frequency,best32.)));
end;
run;
proc datasets nolist;
delete __tempsorted;
run;
quit;
%mend get_frequency;
Then you can call the macro on your original data set timeseries to examine the variable date and create a new macro variable frequency1 with the required frequency.
data work.timeseries;
input date date. value;
format date date9.;
datalines;
01Oct18 3000
01Nov18 4000
01Dec18 6500
01Jan19 7000
01Feb19 4000
01Mar19 5000
01Apr19 7500
01May19 4800
01Jun19 4500
;
run;
%get_frequency(timeseries,date,freqency1)
%put &=frequency1;
This seems to work on your sample data where each date is the first of the month. If your dates are evenly distributed (e.g. always near month start/end, or always near mid-month etc.) then this macro should work ok. Obviously if you have multiple observations per date then it will give the completely incorrect frequency.

Vertical column summation in sas

I have the following piece of result, which i need to add. Seems like a simple request, but i have spent a few days already trying to find the solution to this problem.
Data have:
Measure Jan_total Feb_total
Startup 100 200
Switcher 300 500
Data want:
Measure Jan_total Feb_total
Startup 100 200
Switcher 300 500
Total 400 700
I want individually placed vertical sum results of each column under the respective column please.
Can someone help me arrive at the solution for this request, please?
To do this in data step code, you would do something like:
data want;
set have end=end; * Var 'end' will be true when we get to the end of 'have'.;
jan_sum + jan_total; * These 'sum statements' accumulate the totals from each observation.;
feb_sum + feb_total;
output; * Output each of the original obbservations.;
if end then do; * When we reach the end of the input...;
measure = 'Total'; * ...update the value in Measure...;
jan_total = jan_sum; * ...move the accumulated totals to the original vars...;
feb_total = feb_sum;
output; * ...and output them in an additional observation.
end;
drop jan_sum feb_sum; * Get rid of the accumulator variables (this statement can go anywhere in the step).;
run;
You could do this many other ways. Assuming that you actually have columns for all the months, you might re-write the data step code to use arrays, or you might use PROC SUMMARY or PROC SQL to calculate the totals and add the resulting totals back using a much shorter data step, etc.
proc means noprint
data = have;
output out= want
class measure;
var Jan_total Feb_total;
run;
It depends on if this is for display or for a data set. It usually makes no sense to have a total in the data set and it's just used for reporting.
PROC PRINT has a SUM statement that will add the totals to the end of a report. PROC TABULATE also provides another mechanism for reporting like this.
example from here.
options obs=10 nobyline;
proc sort data=exprev;
by sale_type;
run;
proc print data=exprev noobs label sumlabel
n='Number of observations for the order type: '
'Number of observations for the data set: ';
var country order_date quantity price;
label sale_type='Sale Type'
price='Total Retail Price* in USD'
country='Country' order_date='Date' quantity='Quantity';
sum price quantity;
by sale_type;
format price dollar7.2;
title 'Retail and Quantity Totals for #byval(sale_type) Sales';
run;
options byline;
Results:

How can I create pivot table in SAS?

I have three columns in a dataset: spend, age_bucket, and multiplier. The data looks something like...
spend age_bucket multiplier
10 18-24 2x
120 18-24 2x
1 35-54 3x
I'd like a dataset with the columns as the age buckets, the rows as the multipliers, and the entries as the sum (or other aggregate function) of the spend column. Is there a proc to do this? Can I accomplish it easily using proc SQL?
There are a few ways to do this.
data have;
input spend age_bucket $ multiplier $;
datalines;
10 18-24 2x
120 18-24 2x
1 35-54 3x
10 35-54 2x
;
proc summary data=have;
var spend;
class age_bucket multiplier;
output out=temp sum=;
run;
First you can use PROC SUMMARY to calculate the aggregation, sum in this case, for the variable in question. The CLASS statement gives you things to sum by. This will calculate the N-Way sums and the output data set will contain them all. Run the code and look at data set temp.
Next you can use PROC TRANSPOSE to pivot the table. We need to use a BY statement so a PROC SORT is necessary. I also filter to the aggregations you care about.
proc sort data=temp(where=(_type_=3));
by multiplier;
run;
proc transpose data=temp out=want(drop=_name_);
by multiplier;
var spend;
id age_bucket;
idlabel age_bucket;
run;
In traditional mode 35-54 is not a valid SAS variable name. SAS will convert your columns to proper names. The label on the variable will retain the original value. Just be aware if you need to reference the variable later, the name has changed to be valid.

Contingency table in SAS

I have data on exam results for 2 years for a number of students. I have a column with the year, the students name and the mark. Some students don't appear in year 2 because they don't sit any exams in the second year. I want to show whether the performance of students persists or whether there's any pattern in their subsequent performance. I can split the data into two halves of equal size to account for the 'first-half' and 'second-half' marks. I can also split the first half into quintiles according to the exam results using 'proc rank'
I know the output I want is a 5 X 5 table that has the original 5 quintiles on one axis and the 5 subsequent quintiles plus a 'dropped out' category as well, so a 5 x 6 matrix. There will obviously be around 20% of the total number of students in each quintile in the first exam, and if there's no relationship there should be 16.67% in each of the 6 susequent categories. But I don't know how to proceed to show whether this is the case of not with this data.
How can I go about doing this in SAS, please? Could someone point me towards a good tutorial that would show how to set this up? I've been searching for terms like 'performance persistence' etc, but to no avail. . .
I've been proceeding like this to set up my dataset. I've added a column with 0 or 1 for the first or second half of the data using the first procedure below. I've also added a column with the quintile rank in terms of marks for all the students. But I think I've gone about this the wrong way. Shoudn't I be dividing the data into quintiles in each half, rather than across the whole two periods?
Proc rank groups=2;
var yearquarter;
ranks ExamRank;
run;
Proc rank groups=5;
var percentageResult;
ranks PerformanceRank;
run;
Thanks in advance.
Why are you dividing the data into quintiles?
I would leave the scores as they are, then make a scatterplot with
PROC SGPLOT data = dataset;
x = year1;
y = year2;
loess x = year1 y = year2;
run;
Here's a fairly basic example of the simple tabulation. I transpose your quintile data and then make a table. Here there is basically no relationship, except that I only allow a 5% DNF so you have more like 19% 19% 19% 19% 19% 5%.
data have;
do i = 1 to 10000;
do year = 1 to 2;
if year=2 and ranuni(7) < 0.05 then call missing(quintile);
else quintile = ceil(5*ranuni(7));
output;
end;
end;
run;
proc transpose data=have prefix=year out=have_t;
by i;
var quintile;
id year;
run;
proc tabulate data=have_t missing;
class year1 year2;
tables year1,year2*rowpctn;
run;
PROC CORRESP might be helpful for the analysis, though it doesn't look like it exactly does what you want.
proc corresp data=have_t outc=want outf=want2 missing;
tables year1,year2;
run;