Subtract every element of vector A from every elem

问题:

Does anyone know any way to accomplish the following in a vectorized format?

Rather than subtracting member-wise test1 from test, I would like to subtract every element of test1 from every element of test. So, rather than:

test = c(1:10)
test1 = seq(0.1, 1, 0.1)

test - test1
 [1] 0.9 1.8 2.7 3.6 4.5 5.4 6.3 7.2 8.1 9.0

I want:

test2=vector("list")
for(i in 1:length(test)){
  test2[[i]] = test[i] - test1
}
test2
[[1]]
 [1] 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

[[2]]
 [1] 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0

[[3]]
 [1] 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0

[[4]]
 [1] 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0

[[5]]
 [1] 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0

[[6]]
 [1] 5.9 5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 5.0

[[7]]
 [1] 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0

[[8]]
 [1] 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0

[[9]]
 [1] 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0

[[10]]
 [1] 9.9 9.8 9.7 9.6 9.5 9.4 9.3 9.2 9.1 9.0

Even for vectors of uneven length?

回答1:

outer(test, test1, `-`)
#       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#  [1,]  0.9  0.8  0.7  0.6  0.5  0.4  0.3  0.2  0.1     0
#  [2,]  1.9  1.8  1.7  1.6  1.5  1.4  1.3  1.2  1.1     1
#  [3,]  2.9  2.8  2.7  2.6  2.5  2.4  2.3  2.2  2.1     2
#  [4,]  3.9  3.8  3.7  3.6  3.5  3.4  3.3  3.2  3.1     3
#  [5,]  4.9  4.8  4.7  4.6  4.5  4.4  4.3  4.2  4.1     4
#  [6,]  5.9  5.8  5.7  5.6  5.5  5.4  5.3  5.2  5.1     5
#  [7,]  6.9  6.8  6.7  6.6  6.5  6.4  6.3  6.2  6.1     6
#  [8,]  7.9  7.8  7.7  7.6  7.5  7.4  7.3  7.2  7.1     7
#  [9,]  8.9  8.8  8.7  8.6  8.5  8.4  8.3  8.2  8.1     8
# [10,]  9.9  9.8  9.7  9.6  9.5  9.4  9.3  9.2  9.1     9

回答2:

This does the trick:

lapply(test,function(x) x - test1)

回答3:

A vectorized approach giving you the desired list:

x = rep(test, each=length(test))
split(x- test1, x)

#$`1`
# [1] 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

#$`2`
# [1] 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0

#$`3`
# [1] 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0

#$`4`
# [1] 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0

#$`5`
# [1] 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0

#$`6`
# [1] 5.9 5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 5.0

#$`7`
# [1] 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0

#$`8`
# [1] 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0

#$`9`
# [1] 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0

#$`10`
# [1] 9.9 9.8 9.7 9.6 9.5 9.4 9.3 9.2 9.1 9.0

回答4:

> test = c(1:10)
> test1 = seq(0.1, 1, 0.1)
> lapply(test,function(e) e-test1)
[[1]]
 [1] 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0

[[2]]
 [1] 1.9 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 1.0

[[3]]
 [1] 2.9 2.8 2.7 2.6 2.5 2.4 2.3 2.2 2.1 2.0

[[4]]
 [1] 3.9 3.8 3.7 3.6 3.5 3.4 3.3 3.2 3.1 3.0

[[5]]
 [1] 4.9 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0

[[6]]
 [1] 5.9 5.8 5.7 5.6 5.5 5.4 5.3 5.2 5.1 5.0

[[7]]
 [1] 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0

[[8]]
 [1] 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0

[[9]]
 [1] 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0

[[10]]
 [1] 9.9 9.8 9.7 9.6 9.5 9.4 9.3 9.2 9.1 9.0