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数据中有-9.9用drop删除为什么处理不掉？具体如图

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关键词：drop

试试drop if p8_4=-9.9呢？

可尝试：

1. drop if p8_4 == float(-9.9)

复制代码

具体原因可见：

1. help float
   
2. 
   
3. Although you may store your numeric variables as byte, int, long, float, or double, Stata converts all numbers to double before performing any calculations.
   
4.                      Consequently, difficulties can arise in comparing numbers that have no finite binary representations.
   
5. 
   
6.                      For example, if the variable x is stored as a float and contains the value 1.1 (a repeating "decimal" in binary), the expression x==1.1 will evaluate to false because
   
7.                      the literal 1.1 is the double representation of 1.1, which is different from the float representation stored in x.  (They differ by 2.384 x 10^(-8).) The expression
   
8.                      x==float(1.1) will evaluate to true because the float() function converts the literal 1.1 to its float representation before it is compared with x. (See [U] 13.11
   
9.                      Precision and problems therein for more information.)

复制代码

andruw 发表于 2015-7-2 21:47
可尝试：具体原因可见：

非常非常感谢