readr::read_csv
添加编辑数据时不会更新的属性。例如,
library('tidyverse')
df <- read_csv("A,B,C\na,1,x\nb,1,y\nc,1,z")
# Remove columns with only one distinct entry
no_info <- df %>% sapply(n_distinct)
no_info <- names(no_info[no_info==1])
df2 <- df %>%
select(-no_info)
检查结构,我们看到 B 列仍然存在于df2
:
> str(df)
Classes ‘spec_tbl_df’, ‘tbl_df’, ‘tbl’ and 'data.frame': 3 obs. of 3 variables:
$ A: chr "a" "b" "c"
$ B: num 1 1 1
$ C: chr "x" "y" "z"
- attr(*, "spec")=
.. cols(
.. A = col_character(),
.. B = col_double(),
.. C = col_character()
.. )
> str(df2)
Classes ‘spec_tbl_df’, ‘tbl_df’, ‘tbl’ and 'data.frame': 3 obs. of 2 variables:
$ A: chr "a" "b" "c"
$ C: chr "x" "y" "z"
- attr(*, "spec")=
.. cols(
.. A = col_character(),
.. B = col_double(),
.. C = col_character()
.. )
> attributes(df2)
$class
[1] "spec_tbl_df" "tbl_df" "tbl" "data.frame"
$row.names
[1] 1 2 3
$spec
cols(
A = col_character(),
B = col_double(),
C = col_character()
)
$names
[1] "A" "C"
>
如何删除列(或对数据的任何其他更新)并使更改准确反映在新的数据结构和属性中?