Avoid NA Value when Summarizing data.table in R (Example Code)

In this article you’ll learn how to delete NA values when summarizing a data.table in the R programming language.

Preparing the Example

install.packages("data.table")                                 # Install data.table package
library("data.table")                                          # Load data.table
my_dt <- data.table(A = c(NA, 1:10, NA),                       # Example data
                    B = 101:112,
                    GR = rep(LETTERS[1:4], each = 3))
my_dt                                                          # Display example data.table
#      A   B GR
#  1: NA 101  A
#  2:  1 102  A
#  3:  2 103  A
#  4:  3 104  B
#  5:  4 105  B
#  6:  5 106  B
#  7:  6 107  C
#  8:  7 108  C
#  9:  8 109  C
# 10:  9 110  D
# 11: 10 111  D
# 12: NA 112  D

Example: Summarize data.table & Remove NA

my_dt_new <- my_dt[, lapply(.SD, sum, na.rm = TRUE), by = GR]  # Summarize data.table
my_dt_new
#    GR  A   B
# 1:  A  3 306
# 2:  B 12 315
# 3:  C 21 324
# 4:  D 19 333

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