CODEWITHSUNDEEP
rdataframe
Nikhil Mangire
Nikhil Mangire

Reputation: 407

how to fill values using conditional row in R?

I have following dataframe,

enter image description here

Here I want to add a column 'Constant Vol', where if the 'Year' column is 2006 all the values for 'Constant Vol' should be that od 2006 'Vol'. The result should be like following dataframe.

enter image description here

Upvotes: 0

Views: 50

Answers (2)

akrun
akrun

Reputation: 887881

We can use

library(dplyr)
df %>%
   group_by(Seg) %>%
   mutate(Constnt_Vol = Vol[match(2006, Year)])

data

df <- data.frame(Seg = rep(c("Agri", "Auto"), each  =4), 
       Year  =2006:2009, Vol = c(23, 29, 16, 31, 12, 34, 45, 32))

Upvotes: 0

Ronak Shah
Ronak Shah

Reputation: 389265

Using dplyr, we can group_by Seg and get the corresponding Vol where Year = 2006

library(dplyr)

df %>%
  group_by(Seg) %>%
  mutate(Constnt_Vol = Vol[Year == 2006])

#  Seg    Year   Vol Constnt_Vol
#  <fct> <int> <dbl>       <dbl>
#1 Agri   2006    23          23
#2 Agri   2007    29          23
#3 Agri   2008    16          23
#4 Agri   2009    31          23
#5 Auto   2006    12          12
#6 Auto   2007    34          12
#7 Auto   2008    45          12
#8 Auto   2009    32          12

and in data.table that would be

library(data.table)
setDT(df)[, Constnt_Vol :=  Vol[Year == 2006], Seg]

This is assuming you have only one row with Year = 2006 in each Seg, if there are multiple we can use which.max to get the first one. (Vol[which.max(Year == 2006)]).

data

df <- data.frame(Seg = rep(c("Agri", "Auto"), each  =4), 
       Year  =2006:2009, Vol = c(23, 29, 16, 31, 12, 34, 45, 32))

Upvotes: 1

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