Grokbase Groups R r-help January 2016
FAQ

You can keep it a dataframe as follows:


set.seed(123)
x <- data.frame(a = 1:10, b = 2:11, c = 3:12, other = rnorm(10))
x
     a b c other
1 1 2 3 -0.56047565
2 2 3 4 -0.23017749
3 3 4 5 1.55870831
4 4 5 6 0.07050839
5 5 6 7 0.12928774
6 6 7 8 1.71506499
7 7 8 9 0.46091621
8 8 9 10 -1.26506123
9 9 10 11 -0.68685285
10 10 11 12 -0.44566197
# change the columns in the dataframe
x[1:3] <- lapply(x[1:3], function(a){
+ a[a==7] <- 4 # replace values
+ a[a>7] <- a[a>7] - 1 # decrement
+ a # return value
+ })
x
    a b c other
1 1 2 3 -0.56047565
2 2 3 4 -0.23017749
3 3 4 5 1.55870831
4 4 5 6 0.07050839
5 5 6 4 0.12928774
6 6 4 7 1.71506499
7 4 7 8 0.46091621
8 7 8 9 -1.26506123
9 8 9 10 -0.68685285
10 9 10 11 -0.44566197


?




Jim Holtman
Data Munger Guru


What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.


On Fri, Jan 22, 2016 at 11:38 AM, Dimitri Liakhovitski wrote:

I think I got it:

set.seed(123)
x <- data.frame(a = 1:10, b = 2:11, c = 3:12, other = rnorm(10))
x
temp <- as.matrix(x[1:3])
temp[temp %in% 7] <- 4
temp[temp > 7] <- temp[temp > 7]-1
x[1:3] <- temp
x

It works only with matrices, right? Can't do x[x>7] when x is a data frame?
Thanks!

On Fri, Jan 22, 2016 at 11:34 AM, Dimitri Liakhovitski
wrote:
Hello!

# I have a data frame x:
x <- data.frame(a = 1:10, b = 2:11, c = 3:12, other = rnorm(10))

# First, I need to change every value 7 in columns a:c to 4
# Then, I need to decrease by 1 all values in columns a:c that are >7

What would be the fastest way of doing it?
Thank you!

--
Dimitri Liakhovitski


--
Dimitri Liakhovitski

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