R Question
Fill NA row with previous value iteratively in R
Say you have something like this across various weeks in a given df:
DoW Value
Mon 1234
Tue NA
Wed 5678
Thu 9123
Fri 4567
Sat 8912
Sun 3456
I'd like to fill every Tuesday's NA with Monday's value of it's correspondent week. How can I do this, preferably with the least amount of code possible?
Thanks.
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Answer Source
What about this ?
mydf <- structure(list(DoW = c("Mon", "Tue", "Wed", "Thu", "Fri", "Sat",
"Sun"), Value = c(1234L, NA, 5678L, 9123L, 4567L, 8912L, 3456L
)), .Names = c("DoW", "Value"), class = "data.frame", row.names = c(NA,
-7L))
tuesd_na <- which(mydf$DoW == "Tue" & is.na(mydf$Value))
mydf$Value[tuesd_na] <- mydf$Value[tuesd_na - 1]
mydf
#> DoW Value
#> 1 Mon 1234
#> 2 Tue 1234
#> 3 Wed 5678
#> 4 Thu 9123
#> 5 Fri 4567
#> 6 Sat 8912
#> 7 Sun 3456
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