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我正在尝试将数据框中的三个字符变量转换为因子，并且我不断收到这三个变量之一的错误。有问题的变量 fund.category 有 4 个可能的值：“未定义”、“小”、“大型现有”和“大型新建”。我的代码如下 - 我首先使用 XLConnect 从 Excel 表中读取数据框，然后删除不必要的变量并重命名我保留的变量：

a.projects <- readWorksheet(wb, sheet = "ProjectsDetail")
a.projects.2 <- a.projects[c("ProjectNumber", "BusinessType", "Fund.Category")]
a.projects.2 <- rename(a.projects.2,
                       c("ProjectNumber" = "project.number",
                         "BusinessType" = "business.type",
                         "Fund.Category" = "fund.catetgory"))
str(a.projects.2)
a.projects.2$project.number <- as.factor(a.projects.2$project.number)
a.projects.2$business.type <- as.factor(a.projects.2$business.type)   
a.projects.2$fund.category <- as.factor(a.projects.2$fund.category)

这是 a.projects.2 的结构，在我尝试进行因子转换之前生成：

'data.frame':   4291 obs. of  3 variables:
 $ project.number: chr  "APS-10-02825" "APS-10-02826" "APS-10-02876" "APS-10-03134" ...
 $ business.type : chr  "Office" "Office" "Process Industrial" "K-12 School" ...
 $ fund.catetgory: chr  "Undefined" "Undefined" "Large Existing" "Large New Construction" ...

这是来自控制台的错误：

a.projects.2$fund.category <- as.factor(a.projects.2$fund.category)

Error in `$<-.data.frame`(`*tmp*`, "fund.category", value = integer(0)) : 
replacement has 0 rows, data has 4291

相同的代码对我的其他两个字符变量（project.number 和 business.type）没有产生错误。任何想法为什么这不起作用？

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1 回答 1

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您在之前的声明中拼错了“fund.category”：

a.projects.2 <- rename(a.projects.2,
                       c("ProjectNumber" = "project.number",
                         "BusinessType" = "business.type",
                         "Fund.Category" = "fund.catetgory"))

修正错字，它应该很高兴:-)

要理解错误，

a.projects.2$fund.category返回NULL

as.factor(NULL)返回factor(0)

并且在分配factor(0)给a.projects.2$fund.category您时会出现错误：

Error in `$<-.data.frame`(`*tmp*`, "fund.category", value = integer(0)) : 
replacement has 0 rows, data has 4291
于 2012-09-18T22:57:33.827 回答