使用NA的条件语句从数据框中的列填充值-R

Question

I have a dataframe as follows:

Date        FLOW     Modelled   Infilled
01-01-1992  1.856    1.900      NA
02-01-1992  1.523    1.500      NA
03-01-1992  NA       2.400      NA    
04-01-1992  3.679    3.800      NA

I want to fill the Infilled column with FLOW values. Where there are "NA" values in the FLOW column of the time series I want to replace these NAs with values from the Modelled column.

Answer should look like this:

Date        FLOW     Modelled   Infilled
01-01-1992  1.856    1.900      1.856
02-01-1992  1.523    1.500      1.523
03-01-1992  NA       2.400      2.400    
04-01-1992  3.679    3.800      3.679

I have a solution as follows in excel:

Infilled column   =IF((FLOW="NA"),Modelled,FLOW)

I have not yet found a solution online to help me programme this in R. The time series are pretty lengthy and I have multiple files to do this for, so a loop could be the most suitable solution. I am relatively new to R and I can't figure this out. Help much appreciated!

Answer 1

You are looking for coalesce

library(tidyverse)
dat%>%
   mutate(Infilled=coalesce(FLOW,Modelled))
        Date  FLOW Modelled Infilled
1 01-01-1992 1.856      1.9    1.856
2 02-01-1992 1.523      1.5    1.523
3 03-01-1992    NA      2.4    2.400
4 04-01-1992 3.679      3.8    3.679

In base R you can do:

transform(dat,Infilled=ifelse(is.na(FLOW),Modelled,FLOW))
        Date  FLOW Modelled Infilled
1 01-01-1992 1.856      1.9    1.856
2 02-01-1992 1.523      1.5    1.523
3 03-01-1992    NA      2.4    2.400
4 04-01-1992 3.679      3.8    3.679

Answer 2

We can use base R

dat$Infilled <- dat$FLOW
i1 <- is.na(dat$FLOW)
dat$Infilled[i1] <- dat$Modelled[i1]

---

Or with data.table

library(data.table)
setDT(dat)[, Infilled := FLOW][is.na(FLOW), Infilled := Modelled][]