Question

命令：

t <- data.frame(v = 5:1, v2 = 9:5)
write.csv(t, "t.csv")

产生的文件：

# "","v","v2"
# "1",5,9
# "2",4,8
# "3",3,7
# "4",2,6
# "5",1,5

如何防止将带有行索引的第一列写入文件？

Answer 1

write.csv(t, "t.csv", row.names=FALSE)

来自?write.csv：

row.names: either a logical value indicating whether the row names of
          ‘x’ are to be written along with ‘x’, or a character vector
          of row names to be written.

Answer 2

出于完整性考虑，readr软件包中的write_csv()速度更快，并且从不写入行名

# install.packages('readr', dependencies = TRUE)
library(readr)
write_csv(t, "t.csv")

如果您需要写出大数据，请使用data.table软件包中的fwrite()。它比write.csv和write_csv

都快

# install.packages('data.table')
library(data.table)
fwrite(t, "t.csv")

下面是爱德华在他的网站上发布的benchmark

microbenchmark(write.csv(data, "baseR_file.csv", row.names = F),
               write_csv(data, "readr_file.csv"),
               fwrite(data, "datatable_file.csv"),
               times = 10, unit = "s")

## Unit: seconds
##                                              expr        min         lq       mean     median         uq        max neval
##  write.csv(data, "baseR_file.csv", row.names = F) 13.8066424 13.8248250 13.9118324 13.8776993 13.9269675 14.3241311    10
##                 write_csv(data, "readr_file.csv")  3.6742610  3.7999409  3.8572456  3.8690681  3.8991995  4.0637453    10
##                fwrite(data, "datatable_file.csv")  0.3976728  0.4014872  0.4097876  0.4061506  0.4159007  0.4355469    10

使用write.csv时，防止将行名写入文件

2 个答案: