如何对 R 中的 data.frame 或 tibble 列中的 NA 值的总数求和，并按月和年对它们进行分组

Question

So here is a sample of my Data

year <- c(1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,
      1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,
      1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,
      1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,
      1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,
      1980  ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980   ,1980)

month <- c(1    ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1
       ,1   ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,1  ,2  
       ,2   ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  
       ,2   ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2  ,2)

Q <- c(NA   ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA 
   ,NA  ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,0.3    ,0.3    ,0.28   
   ,0.26    ,0.26   ,0.25   ,0.25   ,0.24   ,0.24   ,0.24   ,0.24   ,0.23   ,0.23   ,NA ,NA 
   ,NA  ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA ,NA)

I combined them into a dataframe called Flow

Flow <- data.frame(year,month,Q)

I can sum or count the number of missing or NA values in my Q column.

sum(is.na(Flow$Q))

Now I am trying to calculate the sum of NA values in each month for the year and eventually each year.

This is where I'm stuck.

group_by(Flow$year, Flow$month) %>%
sum(is.na(Flow$Q) 

Answer 1

With group by, we can use summarise . Also, we don't need the Flow$ inside the group_by

library(dplyr)
Flow %>%
    group_by(year, month) %>% 
    summarise(Nas = sum(is.na(Q)))
# A tibble: 2 x 3
# Groups:   year [1]
#   year month   Nas
#  <dbl> <dbl> <int>
#1  1980     1    28
#2  1980     2    19