r for loop with names mutate - r

Question

The goal is to replace NAs with 0 values in a set of variables using a loop function. Obviously, this is a super simple loop function, but I have no idea why this is not doing what it should.
two additional preferences, suggestions that use the variable names (as opposed to column numbers) and use dplyr are preferred.
library
library(plyr)
library(dplyr)
sample data
y <- structure(list(pid = c(1002L, 1002L, 1002L, 1002L, 1002L, 1002L,1002L, 1002L, 1002L, 1002L), year = 1968:1977, weeks_hd_e = c(3,0, 50, 49, 50, 50, 50, 50, 50, 49), weeks_wf_e = c(4, 6, 0, 0,0, 0, 0, 0, 0, 0), weeks_hd_u = c(NA, NA, 0, 0, 0, 0, 0, 0, 0,0), weeks_hd = c(NA_real_, NA_real_, NA_real_, NA_real_, NA_real_,NA_real_, NA_real_, NA_real_, NA_real_, NA_real_), weeks_wf_u = c(NA,NA, NA, NA, NA, NA, NA, NA, 0, NA), weeks_wf = c(NA_real_, NA_real_,NA_real_, NA_real_, NA_real_, NA_real_, NA_real_, NA_real_, NA_real_,NA_real_)), .Names = c("pid", "year", "weeks_hd_e", "weeks_wf_e","weeks_hd_u", "weeks_hd", "weeks_wf_u", "weeks_wf"), row.names = c(NA,10L), class = "data.frame")
this command works
y <- mutate(y, i = ifelse(!is.na(i), i, 0))
this loop does not
vars <- c("weeks_hd_e", "weeks_hd_u", "weeks_wf_e", "weeks_wf_u", "weeks_hd", "weeks_wf")
for (i in names(vars)) {
y <- mutate(y, i = ifelse(!is.na(i), i, 0))
}
View(y)

Answer 1

i have been given two excellent answers from friends:
for (i in 1:length(vars)){
y[vars[i]][is.na(y[vars[i]])] <- 0
}
or
y[, vars] <- apply(y[, vars], 2, function(x) ifelse(is.na(x), 0, x))

Answer 2

The replace_na command from the tidyr package does exactly what you want.
Use it like this:
install.packages("tidyr")
library(tidyr)
# your data
y <- structure(list(pid = c(1002L, 1002L, 1002L, 1002L, 1002L, 1002L,1002L, 1002L, 1002L, 1002L), year = 1968:1977, weeks_hd_e = c(3,0, 50, 49, 50, 50, 50, 50, 50, 49), weeks_wf_e = c(4, 6, 0, 0,0, 0, 0, 0, 0, 0), weeks_hd_u = c(NA, NA, 0, 0, 0, 0, 0, 0, 0,0), weeks_hd = c(NA_real_, NA_real_, NA_real_, NA_real_, NA_real_,NA_real_, NA_real_, NA_real_, NA_real_, NA_real_), weeks_wf_u = c(NA,NA, NA, NA, NA, NA, NA, NA, 0, NA), weeks_wf = c(NA_real_, NA_real_,NA_real_, NA_real_, NA_real_, NA_real_, NA_real_, NA_real_, NA_real_,NA_real_)), .Names = c("pid", "year", "weeks_hd_e", "weeks_wf_e","weeks_hd_u", "weeks_hd", "weeks_wf_u", "weeks_wf"), row.names = c(NA,10L), class = "data.frame")
# replacing NAs in your dataframe
# specify the variables you want to replace NAs in and the replacement in the `replace` = list argument
y <- replace_na(y, replace = list(weeks_hd_e = 0, weeks_hd_u = 0, weeks_wf_e = 0, weeks_wf_u = 0, weeks_hd = 0, weeks_wf = 0))
Note that this meets your preference to specify the variables by name and is more flexible in terms of replacement, i.e. you can replace NAs in numeric and character variables in the same command.