I have a dataset with three columns. The column user has two actions including action1 and action2. action2 only contains information if action1 column has A data. I want to concatenate P data in action1 with the previous data in action2. For example, if action2 has ac, and the next row has P in action1, I want to change P into Pac, and will continue (all P turn into Pac) until action2 change. Take note that this process should repeat for each user.
df<-read.table(text="
user action1 action2
1 A a
1 B NA
1 P NA
1 P NA
1 A ac
1 P NA
2 B NA
2 P NA
2 A aa
2 P NA
2 AB aa",header=T)
result: (I highlighted those rows that infected)
user action1 action2
1 A a
1 B NA
1 Pa NA <-
1 Pa NA <-
1 A ac
1 Pac NA <-
2 B NA
2 P NA
2 A aa
2 Paa NA <-
2 AB NA
Thank you
library('data.table')
library('zoo')
# Using zoo::na.locf(), fill NA with the previous value and group by user. Also `na.locf` will not remove NA.
setDT(df)[, V3 := na.locf(action2, na.rm = FALSE), by = .(user)]
# combine action1 with V3 column if action1 is equal to 'P' and it is not NA.
df[action1 == 'P' & !(is.na(V3)), action1 := paste0(action1, V3)]
df[, V3 := NULL] # remove V3 column
df
# user action1 action2
# 1: 1 A a
# 2: 1 B NA
# 3: 1 Pa NA
# 4: 1 Pa NA
# 5: 1 A ac
# 6: 1 Pac NA
# 7: 2 B NA
# 8: 2 P NA
# 9: 2 A aa
# 10: 2 Paa NA
# 11: 2 AB aa
Data:
df<-read.table(text="
user action1 action2
1 A a
1 B NA
1 P NA
1 P NA
1 A ac
1 P NA
2 B NA
2 P NA
2 A aa
2 P NA
2 AB aa",header=T, stringsAsFactors = FALSE)
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