CODEWITHSUNDEEP
rdataframe
user1658170
user1658170

Reputation: 858

Change column values in an R dataframe

I have a data frame formatted like this in R:

dataframe

How could I call up all the HEIGHT values where GROUP is equal to B and change them? I.e. from cm to mm.

Upvotes: 2

Views: 56633

Answers (2)

sparrow
sparrow

Reputation: 1101

data = data.frame(
  group = rep(c("A", "B", "C"), each = 4),
  height = c(259, 243, 253, 235, 23.5, 23.6, 23.5, 24.1, 235, 234, 235, 220)
)
data #shows your data

#from cm to mm
data$height[data$group == "B"]  <- data$height[data$group == "B"] * 10

Upvotes: 17

Jilber Urbina
Jilber Urbina

Reputation: 61154

Something like this?

> set.seed(1) # simulating some data
> df <- data.frame(group=rep(c("A", "B", "C"), each=4), height=sample(100:150, 12))
> df
   group height
1      A    113
2      A    118
3      A    128
4      A    143
5      B    109
6      B    141
7      B    142
8      B    129
9      C    127
10     C    102
11     C    108
12     C    107
> # changing `height` for group `B`
> ind <- df$group %in% "B"       # locating group B
> df[ind, 2] <- df[ind, 2] * 10  # changing from cm to mm
> df
   group height
1      A    113
2      A    118
3      A    128
4      A    143
5      B   1090
6      B   1410
7      B   1420
8      B   1290
9      C    127
10     C    102
11     C    108
12     C    107

Upvotes: 4

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