在不知道行号的情况下删除特定行

Question

我想从数据框中删除一行并对结果列求和.我根据其内容知道要删除的行,但不知道它的行号.下面我将介绍三个例子,其中两个有效.使用-删除行仅在第一行要被删除的作品.这是为什么？

我的问题与此类似:如何删除R中数据帧的第一行？ 但是,根据行号删除行.

# This works.

state = 'OH'

my.data = read.table(text = "
      county  y1990 y2000
        cc       NA    2
        OH       NA   10
        bb       NA    1
", sep = "", header = TRUE, na.strings = "NA", stringsAsFactors = FALSE)

my.colsums2 <- colSums(my.data[!(my.data$county == state), 2:ncol(my.data)], na.rm=TRUE)
my.colsums2

# y1990 y2000 
#    0     3

# This works.

my.data = read.table(text = "
      county  y1990 y2000
        OH       NA   10
        cc       NA    2
        bb       NA    1
", sep = "", header = TRUE, na.strings = "NA", stringsAsFactors = FALSE)

my.colsums2 <- colSums(my.data[-(my.data$county == state), 2:ncol(my.data)], na.rm=TRUE)
my.colsums2

# y1990 y2000 
#    0     3

# This does not work.

my.data = read.table(text = "
      county  y1990 y2000
        cc       NA    2
        OH       NA   10
        bb       NA    1
", sep = "", header = TRUE, na.strings = "NA", stringsAsFactors = FALSE)

my.colsums2 <- colSums(my.data[-(my.data$county == state), 2:ncol(my.data)], na.rm=TRUE)
my.colsums2

# y1990 y2000 
#    0    11

我猜我仍然困惑过之间的差异!和-.谢谢你的任何建议.

Answer 1

这应该清除-和之间的区别!,我怀疑你可以从那里拿走它;)

my.data$county == state
# [1]  TRUE FALSE FALSE

!(my.data$county == state)
# [1] FALSE  TRUE  TRUE

-(my.data$county == state)
# [1] -1  0  0

!,否定布尔值,是你应该在这里使用的运算符.