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Sorting observations

Lesson Description
-
  • Sometimes, we want to work with the concept of "Sorting observations" in a clear, repeatable way.
  • This lesson walks through a simple example and shows the key steps.
  • We will see one approach on how we can do it in SAS and R.
data CLASS;
 infile datalines dlm='|' dsd missover;
input Name : $8. Sex : $1. Age : best32. Height : best32. Weight : best32.;
label ;
 format ;
 datalines4;
Alfred|M|14|69|112.5
Henry|M|14|63.5|102.5
James|M|12|57.3|83
;;;;
 run;

proc sort data=class out=sorted;
     by age descending height;
 run;

 
  • This SAS code snippet demonstrates how to sort a dataset named "class" based on multiple variables, "age" and "height," in descending order and store the sorted dataset in a new dataset named "sorted."
  • The proc sort procedure is used to perform the sorting operation. The data statement specifies the input dataset to be sorted, which is "class" in this case. The out option specifies the output dataset name, which is "sorted." The by statement is used to define the sorting order by specifying the variables to sort by, which are "age" and "height" in this case.
  • By default, SAS performs ascending sorting for each variable specified in the by statement. To sort a variable in descending order, the descending keyword should be placed immediately after that variable. In this code snippet, the "age" variable is sorted in descending order, and the "height" variable is sorted in ascending order since no descending keyword is specified for it.
  • After executing the proc sort procedure, the sorted dataset "sorted" will contain the same columns and observations as the original "class" dataset, but the rows will be arranged in descending order based on the "age" variable and ascending order based on the "height" variable.
library(tidyverse)

class<-tribble(
~Name,~Sex,~Age,~Height,~Weight,
"Alfred","M",14,69,112.5,
"Henry","M",14,63.5,102.5,
"James","M",12,57.3,83,
)

sorted<-arrange(class,Age,desc(Height))
  • This R Tidyverse code snippet demonstrates how to sort a data frame named "class" based on multiple variables, "Age" and "Height," in ascending and descending order, respectively, using the arrange function from the dplyr package. The sorted data frame is stored in a new data frame named "sorted."
  • The arrange function is used to perform the sorting operation. The first argument specifies the input data frame to be sorted, which is "class" in this case. The subsequent arguments define the sorting order by specifying the variables to sort by, which are "Age" and "Height" in this case.
  • By default, arrange performs ascending sorting for each variable specified. To sort a variable in descending order, the desc function is used, which is applied to the "Height" variable in this code snippet.
  • After executing the arrange function, the "sorted" data frame will contain the same columns and observations as the original "class" data frame, but the rows will be arranged in ascending order based on the "Age" variable and descending order based on the "Height" variable.
class <- data.frame(
  Name = c("Alfred", "Henry", "James"),
  Sex = c("M", "M", "M"),
  Age = c(14, 14, 12),
  Height = c(69, 63.5, 57.3),
  Weight = c(112.5, 102.5, 83)
  , stringsAsFactors = FALSE
)

sorted <- class[order(class$Age, -class$Height), ]
  • order() returns row order; use - for descending sort.
  • data[order(...), ] applies the sort to the data frame.