Question

我收到了错误

Error in if (condition) { : argument is not interpretable as logical

或

Error in while (condition) { : argument is not interpretable as logical

这是什么意思，我该如何预防？

Answer 1

对condition的评估导致R无法解释为合乎逻辑的东西。您可以使用，例如

重现这一点

if("not logical") {}
Error in if ("not logical") { : argument is not interpretable as logical

在if和while条件下，R会将零解释为FALSE，将非零数字解释为TRUE。

if(1) 
{
  "1 was interpreted as TRUE"
}
## [1] "1 was interpreted as TRUE"

但这很危险，因为返回NaN的计算会导致此错误。

if(sqrt(-1)) {}
## Error in if (sqrt(-1)) { : argument is not interpretable as logical
## In addition: Warning message:
## In sqrt(-1) : NaNs produced

最好始终将逻辑值作为if或while条件传递。这通常表示包含comparison operator（==等）或logical operator（&&等）的表达式。

使用isTRUE有时可以帮助您避免此类错误，但请注意，例如isTRUE(NaN)为FALSE，这可能是您想要的，也可能不是。

if(isTRUE(NaN)) 
{
  "isTRUE(NaN) was interpreted as TRUE"
} else
{
  "isTRUE(NaN) was interpreted as FALSE"
}
## [1] "isTRUE(NaN) was interpreted as FALSE"

同样，字符串"TRUE" / "true" / "T"和"FALSE" / "false" / "F"可用作逻辑条件。

if("T") 
{
  "'T' was interpreted as TRUE"
}
## [1] "'T' was interpreted as TRUE"

同样，这有点危险，因为其他字符串会导致错误。

if("TRue") {}
Error in if ("TRue") { : argument is not interpretable as logical

另见相关错误：

Error in if/while (condition) { : argument is of length zero

Error in if/while (condition) {: missing Value where TRUE/FALSE needed

if (NULL) {}
## Error in if (NULL) { : argument is of length zero

if (NA) {}
## Error: missing value where TRUE/FALSE needed

if (c(TRUE, FALSE)) {}
## Warning message:
## the condition has length > 1 and only the first element will be used

if / while（condition）出错：参数不能解释为逻辑

1 个答案: