SAS 基础：KEEP 语句和 KEEP = 选项

Question

您好，我是 SAS 新手，我发现了 SAS 基础编程参考表。在“数据步骤：控制变量输出”部分中，框中的示例代码让我感到困惑。

示例代码是否错误？因为 KEEP 语句中的 store_name 列从未被引用过，所以 SAS 应该无法执行 KEEP 语句。

我使用以下代码测试了代码并收到错误：

DATA work.cars (KEEP = Model Type);
    SET sashelp.cars (DROP = Invoice);
    KEEP MSRP drivetrain;
RUN;

错误消息显示 “警告：从未引用过 DROP、KEEP 或 RENAME 列表中的变量 Model。 警告：从未引用过 DROP、KEEP 或 RENAME 列表中的变量 Type。”

这是否意味着示例代码是错误的？

Answer 1

OUTPUT 数据集上的 KEEP= 数据集选项将应用于 DATA 步骤定义的数据集。 因此，在这种情况下，数据步骤中的 KEEP 语句意味着仅输出 MSRP 和 DRIVETRAIN 变量。 因此，在 WORK.CARS 输出数据集名称的 KEEP= 数据集选项中引用任何其他变量都会发出您看到的警告。

请注意，您可以使用 DKROCOND（对于输入数据集，DKRICOND）系统选项控制 SAS 如何处理此类事物。

示例：

1    options dkrocond=nowarn;
2    DATA work.cars (KEEP = Model Type);
3        SET sashelp.cars (DROP = Invoice);
4        KEEP MSRP drivetrain;
5    RUN;

NOTE: There were 428 observations read from the data set SASHELP.CARS.
NOTE: The data set WORK.CARS has 428 observations and 0 variables.
NOTE: DATA statement used (Total process time):
      real time           0.01 seconds
      cpu time            0.01 seconds


6    options dkrocond=error;
7    DATA work.cars (KEEP = Model Type);
8        SET sashelp.cars (DROP = Invoice);
9        KEEP MSRP drivetrain;
10   RUN;

ERROR: The variable Model in the DROP, KEEP, or RENAME list has never been referenced.
ERROR: The variable Type in the DROP, KEEP, or RENAME list has never been referenced.
NOTE: The SAS System stopped processing this step because of errors.
WARNING: The data set WORK.CARS may be incomplete.  When this step was stopped there were 0 observations and 0 variables.
WARNING: Data set WORK.CARS was not replaced because this step was stopped.
NOTE: DATA statement used (Total process time):
      real time           0.01 seconds
      cpu time            0.01 seconds