变量的数据格式问题

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现有变量x，数据为float型，format为numeric

其中一个观测值的x为9.2，输入后自动存储为9.1999998。

并且，在使用语句诸如 drop if x==9.2 时，选取不到该观测值；
drop if x <9.2 也会把该观测值drop掉。
看来是真的把该观测值的x作为9.1999998处理了。

请问大家，该怎么解决呢？
谢谢！

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关键词：数据格式 numeric format float FORMA

format x %10.1f

ermutuxia 发表于 2014-10-28 11:28
format x %10.1f

非常感谢解答！
但是，使用该命令后，还是没能解决，可以再帮我看看吗

format x %10.1f
执行后的数据格式是这样的。==, > 等符号还是存在识别问题

gen x_3=string(x,"%10.1f")
browse if x_3=="9.2"

capture drop x_4
gen double x_4=real(string(x,"%10.1f"))

Stata stores numbers in binary, and this has a second effect on numbers less than 1.  1/10 has no perfect binary representation just as 1/11 has no perfect decimal
    representation.  In float, .1 is stored as .10000000149011612.  Note that there are 7 digits of accuracy, just as with numbers larger than 1.  Stata, however, performs all
    calculations in double precision.  If you were to store 0.1 in a float called x and then ask, say, list if x==.1, there would be nothing in the list.  The .1 that you just
    typed was converted to double, with 16 digits of accuracy (.100000000000000014...), and that number is never equal to 0.1 stored with float accuracy.

    One solution is to type list if x==float(.1).  The float() function rounds its argument to float accuracy; see [D] functions.  The other alternative would be store your
    data as double, but this is probably a waste of memory.  Few people have data that is accurate to 1 part in 10 to the 7th.  Among the exceptions are banks, who keep
    records accurate to the penny on amounts of billions of dollars.  If you are dealing with such financial data, store your dollar amounts as doubles.

ermutuxia 发表于 2014-10-30 10:48
capture drop x_4
gen double x_4=real(string(x,"%10.1f"))

我忘记回复了。
多谢前辈指点，受教了！