DIF函数取的是变量当前值与前一个值的差值,可以这样理解DIF(X)=X - LAG(X)。看示例代码,很容里理解这两个Function的用法,下面我说一个LAG函数的注意点,看如下代码。 示例代码 示例代码结果 代码中,有个条件语句:只有当X>2时,才会执行lag_x = lag(x)。也就是说,只有当X=3,5,7的时候,LAG函数才会被...
However, when it is executed conditionally, the LAG function only retrieves values from observations for which the condition is satisfied.YunchaoSilver SpringScientific Systems
Learning to love the SAS LAG functionThe LAG and DIF functions (introduced in the SAS 1979 edition) are often used to get access to the previous value of a variable in a DATA step. For each defined LAG and DIF function in a data step a separate queue is maintained.Because programmers ...
Variables: To correctly identify the first and last observations in a BY group, the data must be sorted. Retaining Values: When using the RETAIN statement to carry forward values within BY groups, sorting is crucial. Lag Functions: Functions like LAG require sorted data to correctly reference ...
That becomes evident when the LAG function is executed conditionally, as in the treatment of BY groups below. As an illustration, consider observations 232 through 237 generated by Example 1 program, and presented in Ta- ble 3. This shows the last two cases for IBM and the first four for ...
By customer; Lag_sell_ind=lag(sell_ind); If first.customer then Lag_sell_ind=.; Run; But it does not return the expected output. In sql I would probably use partition by customer over time but I do not know how to do the same in SAS....
我不使用sas，所以请把我的答案作为使用sas的提示lag函数，其他问题，如日期转换或计算差异由您决定。这...
我不使用sas，所以请把我的答案作为使用sas的提示lag函数，其他问题，如日期转换或计算差异由您决定。这...
Use theLAGfunction to examine the priorstsvalue. Be careful about using LAGinsidea conditional clause (which is not happening here). In this example the LAG is occurring in thetest expression. Example: The test expression is a little tricky if you are new to SAS and DATA Step. ...
另外, 從CIFoutdataset也可以擷取每12個月的number at risk數值. 我的作法是先建立一個兩組分別有0, 12, 24, 36, 48, 60 這幾列的dataset (ie. NAtRiskTable); 將它跟CIFout合併之後, 依觀察時間 (Follow) 倒序 (descending) 排列, 才能將 >= 該時間點的數值, 例用 lag function取下來. 新增的XAt...