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rloopsstatisticsdummy-variablegenerate
Aura
Aura

Reputation: 51

How to use while loop to creat a dummy variable based on an existing variable?

I have a categorical variable called "X1" and a dummy variable called "X2". Now I want to create a dummy variable X3 in a way that follows this logic:

If in any rows of any categories of X1, at least one row gets X2=1, then put X3=1 for all the rows of that category, otherwise 0.

X1<-c(1,1,2,2,,3,3)
X2<-c(0,1,0,0,1,1)

The desired output I am looking for is like this:

X1 X2  X3
 1  0   1
 1  1   1
 2  0   0
 2  0   0
 3  1   1
 3  1   1

I appreciate any help on this.

Upvotes: 0

Views: 157

Answers (3)

akrun
akrun

Reputation: 887511

Using collapse

library(collapse)
ftransform(df, X3 = fmax(X2, X1, TRA = 'replace_fill'))

data

df <- structure(list(X1 = c(1, 1, 2, 2, 3, 3), X2 = c(0, 1, 0, 0, 1, 
1)), class = "data.frame", row.names = c(NA, -6L))

Upvotes: 0

Gregor Thomas
Gregor Thomas

Reputation: 145965

Here's a dplyr solution:

df = data.frame(
  X1 = c(1,1,2,2,3,3),
  X2 = c(0,1,0,0,1,1)
)


library(dplyr)
df %>%
  group_by(X1) %>%
  mutate(X3 = ifelse(1 %in% X2, 1, 0))
# # A tibble: 6 x 3
# # Groups:   X1 [3]
#      X1    X2    X3
#   <dbl> <dbl> <dbl>
# 1     1     0     1
# 2     1     1     1
# 3     2     0     0
# 4     2     0     0
# 5     3     1     1
# 6     3     1     1

Here's the same idea in base R:

df$X3 = with(df, ave(X2, X1, FUN = function(x) ifelse(1 %in% x, 1, 0)))
df
#   X1 X2 X3
# 1  1  0  1
# 2  1  1  1
# 3  2  0  0
# 4  2  0  0
# 5  3  1  1
# 6  3  1  1

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 389135

You can get the max value of X2 in each group (X1).

library(dplyr)
df %>% group_by(X1) %>% mutate(X3 = max(X2)) %>% ungroup

#     X1    X2    X3
#  <dbl> <dbl> <dbl>
#1     1     0     1
#2     1     1     1
#3     2     0     0
#4     2     0     0
#5     3     1     1
#6     3     1     1

In base R and data.table :

#Base R
transform(df, X3 = ave(X2, X1, FUN = max))

#data.table
library(data.table)
setDT(df)[, X3 := max(X2), X1]

data

X1<-c(1,1,2,2,3,3)
X2<-c(0,1,0,0,1,1)
df <- data.frame(X1, X2)

Upvotes: 2

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