OBS= tells SAS when to stop processing observations. To determine when to stop processing, SAS uses the value for OBS= in a formula that includes the value for OBS= and the value for FIRSTOBS=. The formula is (obs - firstobs) + 1 = results

2020年1月2日 · 程序在编译时nobs=观测总数就会传送给last变量，接下来程序读入class进入PDV，数据指针直接获取last值并读取最后一条数据，输出并停止Data步。 这样的代码要读入所有数据直到发现是最后末尾才输出，显然前面nobs-1条读取操作都是没有用的。

The OBS= data set option enables you to select observations from SAS data sets. You can select observations to be read from external data files by using the OBS= option in the INFILE statement. Examples

OBS= tells SAS when to stop processing observations or records. To determine when to stop processing, SAS uses the value for OBS= in a formula that includes the value for OBS= and the value for FIRSTOBS=. The formula is (obs - firstobs) + 1 = results

The SET statement's OBS= option tells SAS to stop reading the data from the input SAS data set at the line number specified by OBS. We'll start by using the OBS= option to create the data set that we'll be working with throughout this lesson.

2018年7月3日 · Reading the descriptor portion is one of the most efficient and quickest ways of determining the number of observations in a SAS data set. Here are some examples: /* SAS V9.x and higher */ data _NULL_; if 0 then set sashelp.class nobs=n; call symputx('nrows',n); stop; run; %put nobs=&nrows;

The OBS= data set option enables you to select observations from SAS data sets. You can select observations to be read from external data files by using the OBS= option in the INFILE statement.

OBS= tells SAS when to stop processing observations or records. To determine when to stop processing, SAS uses the value for OBS= in a formula that includes the value for OBS= and the value for FIRSTOBS=.

在SAS中，使用obs（observation）来限定数据集中需要处理的数据观察个数。obs是SAS中的一个系统变量，用于控制分析过程中的观察个数。 使用obs可以对数据集进行限定，实现只处理数据集的前n行观察值的目的。obs可以单独使用，也可以与其他SAS语句组合使用。

2018年3月14日 · OBS can be a system option or a dataset option, it limits the number of observarions read in a proc or a datastep. OBS normally decides the number of the last observation read. If, however, you have tables with "holes" in them (deleted observations), the results can vary a bit. Look at this: