r-如何导入带有空白单元格的csv

Question

当我导入csv时，它显示为具有以下格式的数据帧

firstcol <- c("A","","D","Z")
seccol <- c("W","Y","C","")
thircol <- c("","H","Q","M")
df <- data.frame(firstcol,seccol,thircol)
#    > df
#      firstcol seccol thircol
#    1        A      W        
#    2               Y       H
#    3        D      C       Q
#    4        Z              M

当我键入levels(df$firstcol)时

输出为：[1] "" "A" "D" "Z"

如何导入csv，使单元格被读取为空单元格，而不是观察？

Answer 1

我们可以使用na.strings = ""，这样空白单元格将被读取为NA

df1 <- read.csv('file.csv', na.strings = '', 
strip.white = TRUE, stringsAsFactors = FALSE)

Answer 2

您可以在读取.csv 时将值读取为NA

df1 <- read.csv('file.csv', header=T, na.strings=c(""))