更新时间:2023-11-18 23:01:16
我觉得这一切都过于复杂了.条件 2 已经包含了所有其余的条件,好像一列中至少有两个非 NA
值,显然整列都不是 NA
.如果一列中至少有两个连续的值,那么显然该列包含多个值.因此,这不是 3 个条件,而是全部汇总为一个条件(我不希望每列运行许多函数,而是在每列运行 diff
之后 - 对整个事物进行矢量化):
I feel like this is all over-complicated. Condition 2 already includes all the rest of the conditions, as if there are at least two non-NA
values in a column, obviously the whole column aren't NA
s. And if there are at least two consecutive values in a column, then obviously this column contains more than one value. So instead of 3 conditions, this all sums up into a single condition (I prefer not to run many functions per column, rather after running diff
per column- vecotrize the whole thing):
cond <- colSums(is.na(sapply(df, diff))) < nrow(df) - 1
这是可行的,因为如果一列中没有连续的值,则整列将变为 NA
.
This works because if there are no consecutive values in a column, the whole column will become NA
s.
那么,就
df[, cond, drop = FALSE]
# A E
# 1 0.018 NA
# 2 0.017 NA
# 3 0.019 NA
# 4 0.018 NA
# 5 0.018 NA
# 6 0.015 0.037
# 7 0.016 0.031
# 8 0.019 0.025
# 9 0.016 0.035
# 10 0.018 0.035
# 11 0.017 0.043
# 12 0.023 0.040
# 13 0.022 0.042
根据您的编辑,您似乎有一个 data.table
对象,并且您还有一个 Date
列,因此代码需要一些修改.
Per your edit, it seems like you have a data.table
object and you also have a Date
column so the code would need some modifications.
cond <- df[, lapply(.SD, function(x) sum(is.na(diff(x)))) < .N - 1, .SDcols = -1]
df[, c(TRUE, cond), with = FALSE]
一些解释:
.SD
进行操作时指定 .SDcols = -1
(这意味着 Sub Data in data.table
is) .N
只是行数(类似于 nrow(df)
c(TRUE,...
data.table
默认使用非标准评估,因此,如果您想像在 data.frame
中一样选择列,则需要指定 with = FALSE
.SDcols = -1
when operating on our .SD
(which means Sub Data in data.table
is) .N
is just the rows count (similar to nrow(df)
c(TRUE,...
data.table
works with non standard evaluation by default, hence, if you want to select column as if you would in a data.frame
you will need to specify with = FALSE
不过,更好的方法是使用 := NULL
A better way though, would be just to remove the column by reference using := NULL
cond <- c(FALSE, df[, lapply(.SD, function(x) sum(is.na(diff(x)))) == .N - 1, .SDcols = -1])
df[, which(cond) := NULL]