此时的数据读取方式如下:在SAS读取某一行观测值时,首先读取足够的变量以便决定是否需要保留此行的观测值。然后在input语句结尾加符号@,叫做a trailing at(called atrailing at),这告诉SAS先停在(hold)此行,同时用IF语句检测此观测值是否满足需要,如果是,那么可以再用一个input语句来读取现有的变量。 例子有一个关...
在DATA STEP 使用:构造子集 IF 语句.(subsetting IF statement) 语法: IF expression; 例: IF Sex = ' f ' ; IF expression; 这样的看起来有点怪,但是正确的. 表明:当expression 是TRUE时, SAS继续执行 DATA step。 如果expression 是 FALSE, 对当前observation不继续执行下面的语句,且,该observation不加入...
(1)IF语句是面向“程序数据向量”(Program Data Vector)的,对当前PDV中的数据进行判断,满足条件时将其写入到外部数据集;WHERE语句也是面向PDV的,它使用于从外部数据源读数据到PDV之前进行判断,当满足条件时才被写入到PDV。显然一个在写入PDV之前,一个在写入PDV之后,两者是有差异的。 (2)当没有数据集选项firstobs...
data dataset; set input_dataset; if y = 0 then x = 0; else x = 1; run; 在上面的代码中,我们使用IF语句来判断y的值。如果y等于0,则将x设置为0,否则将x设置为1。这样,我们就根据条件设置了等于0或1的变量x。 SAS是一种功能强大的统计分析软件,广泛应用于数据分析、数据挖掘、商业智能等领域...
If you use an undeclared variable, it will be assigned a default length of 8 when the SUBSTR function is compiled. When you use the SUBSTR function on the left side of an assignment statement, SAS replaces the value of variable with the expression on ...
Of course, it is definitely ok that if we use “if…then/else”statement to complete this task. But I think we apply user-defined format is more efficient to handle this work. And programs are more easily to maintain if plenty of codes are r...
1:where和If最本质的区别,以及一些小的区别 1.1:The WHERE statement examines what is in the input page buffer and selects observations before they are loaded in the program data vector, which results in a savings in CPU operations(Where从buffer中进行筛选再读入pdv) ...
上面的代码中有几点需要注意的,第一,infile statement,这个语句指明了raw data数据存储的路径,类似于R中的setwd。当然了,与R中一样,存储路径是可以设定默认的,如果数据集正好存储在默认的路径之下,这句话也就可以简化成raw data的名称了。此外,除以引号不能省略。在一些场合,我们还会使用到infile的一些 ...
sas条件判断语句where,if的区别，以及where选项 1：where和If最本质的区别，以及⼀些⼩的区别 1.1：The WHERE statement examines what is in the input page buffer and selects observations before they are loaded in the program data vector, which results in a savings in CPU operations(Where从buffer...
Re: If statement - SAS practice exam Posted 05-26-2021 04:04 AM (2511 views) | In reply to jimbarbour Thank you very much. Left intending the datalines did the trick. I am running the code in SAS OnDemand. Has this always been the case? I was under the impression that SAS st...