Replace the values of a dataframe with for loop

Question

The question is:

1) If there is a data frame with 5 rows as follow:

x = c(0,1,3,4,8)
y = c(3,4,6,8,9)
z = c(5,7,3,6,10)
xyz = data.frame(rbind(x,y,z))

x  0  1  3  4  8
y  3  4  6  8  9
z  5  7  3  6 10

I want to replace the numbers with 0 if they are smaller than the mean of every row using for loop in R. For example, if (xyz[i,] < mean(xyz[i,] ) then:

x  0  0  0  4  8
y  0  0  6  8  9
z  0  7  0  0 10

I use the for loop of R as follow:

for(i in 1:3)
{
  j = c(1:5)
  if(xyz[i,j] < rowMeans(xyz[i,]))
     xyz[i,j] = 0
}

Warning messages: 1: In if (xyz[i, j] < rowMeans(xyz[i, ])) xyz[i, j] = 0 : the condition has length > 1 and only the first element will be used…… Any help is appreciated!

Sotos · Accepted Answer · 2019-04-24 07:23:08Z

4

You don't need a for loop. You can simply do,

xyz[xyz < rowMeans(xyz)] <- 0

answered Apr 24, 2019 at 7:23

Sotos

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Comments

Omry Atia · Accepted Answer · 2019-04-24 07:22:27Z

1

Your error is that you need to loop over j as well as i:

for(i in 1:3){
  for (j in 1:5) {
    if(xyz[i,j] < rowMeans(xyz[i,]))
    xyz[i,j] = 0
  }
}

answered Apr 24, 2019 at 7:22

Omry Atia

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