I am using the data from the AdventureWorksDW2017 database. The third column gives the values, which are aggregated over rows and columns.Īs you are probably already used to in my data science articles, I will start with preparing some data. The second column is transposed its values are used for the new columns’ names. The first column is giving the row groups. You need three columns for the operation. Pivoting, using SQL pivot is a similar operation. Transposing data does not involve aggregations. However, you might get data in SQL Server form a matrix from other systems, and meet the need to transpose it. A row represents an entity, and a column an attribute of an entity. A SQL Server table is a slightly different structure, where rows and columns are not equivalent and interchangeable. The data frames in R and Python are actually matrices, and therefore transposing is not a problem. Transposing a matrix means reversing rows and columns. In this article, in the series, we’ll discuss understanding and preparing data by using SQL transpose and SQL pivot techniques. Other options available in the PROC TRANSPOSE statement that can be found in the SAS Help Guide.In data science, understanding and preparing data is critical, such as the use of the SQL pivot operation. The resulting dataset will have one row for each variable identified in the VAR statement. For wide-to-long datasets, there are usually multiple variables in the VAR statement.For long-to-wide datasets, there is usually one variable in the VAR statement.These are the values that will appear in the cells of the transposed variables. The VAR statement is where you actually tell SAS what variables you want transposed.However, if you do supply an ID variable, it will determine the column structure. For wide-to-long transposes, you typically do not need an ID variable.There will be one column for each unique value of the ID variable (or if multiple ID variables are present, one column for each unique combination of values). For long-to-wide transposes, the ID variable(s) determine the structure of the columns in the transposed dataset.The ID statement assigns names to the transposed value columns that match the values in the variable listed in the ID statement.For wide-to-long transposes, the BY variable(s) determine the row structure of the long data that is, it determines the repetition of the rows.For long-to-wide transposes, the BY variable(s) should uniquely identify each row.Your data must be sorted on your BY variables before running PROC TRANSPOSE. You can include more than one variable in the BY statement. The BY statement is used to determine the row structure of the transposed dataset.The OUT keyword says that the transposed dataset should be created as a new dataset called New-dataset-name.The PROC TRANSPOSE statement tells SAS to execute the transpose procedure on an existing dataset called Dataset-name.PROC TRANSPOSE DATA=Dataset-name OUT=New-dataset-name In SAS, PROC TRANSPOSE can perform simple transposes, as well as wide-to-long and long-to-wide restructuring of datasets. To do this, you might want to transpose the data so that each patient has one line of data that includes both weight values (i.e., a wide dataset), like below: Unique Patient ID Now suppose you want to create a scatterplot of how the patients' weights changed between their 1-month and 3-month follow-up visits, or compute the correlation between these measurements. This arrangement would be considered "long format", since there are multiple rows associated with each subject. In this situation, the patient identifier and the type of visit are both "key" variables that uniquely identify each record while the patient identifier uniquely identifies a given subject. A single visit record might contain information about the patient's name, the type of visit, and the weight of the patient during that visit. That is, each row of the "appointments" dataset corresponds to visit. As patients come into the clinic, each visit is recorded in the clinic’s records. Visualizing a set of data in "long" and "wide" formsĬonsider a clinic where patients come in for 1-month and 3-month follow-up visits after some procedure.
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