## Count NAs between first and last occured numbers

Here is my toy dataset

df <- tribble( ~x, ~y, ~z, 7, NA, 4, 8, 2, NA, NA, NA, NA, NA, 4, 6)

I want to get a dataframe with a number of `NA`

s for each variable only between the first and the last occurrence of numbers in each column and number of `NA`

s between the first occurred number and last row. So, for this example, the desired solution is

desired_df <- tribble(~vars, ~na_count_between_1st_last_num, ~na_count_between_1st_num_last_row, "x", 0, 2, "y", 1, 1, "z", 2, 2)

How can I get the desired output?

`na.trim`

trims NAs off both ends or just the left or right end if we specify `sides="left"`

or `sides="right"`

so:

library(dplyr) library(tibble) library(tidyr) library(zoo) df %>% pivot_longer(everything()) %>% group_by(name) %>% summarize(na1 = sum(is.na(na.trim(value))), na2 = sum(is.na(na.trim(value, "left")))) %>% ungroup

giving:

# A tibble: 3 x 3 name na1 na2 <chr> <int> <int> 1 x 0 2 2 y 1 1 3 z 2 2

**Count NA Values in R (Example),** How to determine the number of NA values in the R programming language - 3 examples - Count First, we have to create an example vector with NA values:� If you want to count or sum first n values in a row, you can do as below. Select a blank cell that you want to put the calculated result into, and enter this formula =SUM(OFFSET(A20,0,0,1,A23)), press Enter key to get the calculation. See screenshot: Tip: 1. To count first n numeric strings in a row, use this formula =COUNT(OFFSET(A20,0,0,1,A23)). 2.

Here is an idea via base R,

f1 <- function(x) {i1 <- which(!is.na(x)); head(i1, 1):tail(i1, 1) } f2 <- function(x) {i1 <- which(!is.na(x)); head(i1, 1):length(x) } merge(stack(sapply(df, function(i) sum(is.na(i[f1(i)])))), stack(sapply(df, function(i) sum(is.na(i[f2(i)])))), by = 'ind') # ind values.x values.y #1 x 0 2 #2 y 1 1 #3 z 2 2

**Different ways to count NAs over multiple columns – Sebastian ,** There are a number of ways in R to count NAs (missing values). the question “ how many NAs are there in each column of my dataframe”? The dot . refers to what was handed over by the pipe, ie., the output of the last step. I want the count to show up in the first column for each row's data. For example column one should show a value of 6 for project "test8" first cell with data "0.5" then 4 blank cells, then last cell with data "4" . That's 2 cells with data, and 4 blank cells in between. The project duration is 6 weeks, 2 active and 4 inactive.

Here is one possibility using two functions:

fun1 <- function(x) { #count NA between first and last non NA idx1 <- cumsum(!is.na(x)) > 0 #identify leading NA idx2 <- rev(cumsum(!is.na(rev(x))) > 0) #identify trailing NA sum(is.na(x[idx1 & idx2])) } fun2 <- function(x) {#count NA between first non-NA and last element idx1 <- cumsum(!is.na(x)) > 0 #identify leading NA sum(is.na(x[idx1])) }

Afterwards you just summarise your data.frame and reshape it:

df %>% summarise_all(list(m1 = ~fun1(.), m2 = ~fun2(.))) %>% pivot_longer(cols = everything(), names_pattern = "^(.)_(.*)$", names_to = c("vars", "a"), values_to = "x") %>% spread(a, x) # A tibble: 3 x 3 vars m1 m2 <chr> <int> <int> 1 x 0 2 2 y 1 1 3 z 2 2

**How do I count the number of NaNs in a Vector?,** Learn more about nan, array, vector, counting, count MATLAB. I want to look for the column a(i,:) which contains the least number of Nans, how do I do To get the final answer we want to find which column has the smallest sum. where the ~ notation allows for the first output argument to be ignored. An Error Occurred. tally() is a convenient wrapper for summarise that will either call n() or sum(n) depending on whether you're tallying for the first time, or re-tallying. count() is similar but calls group_by() before and ungroup() after. If the data is already grouped, count() adds an additional group that is removed afterwards. add_tally() adds a column n to a table based on the number of items within each

Here is another option using `data.table::nafill`

:

library(data.table) natrail <- colSums(is.na(as.data.table(nafill(df, "nocb")))) nastart <- colSums(is.na(as.data.table(nafill(df, "locf")))) n1last <- nrow(df) - colSums(!is.na(df)) - nastart n1num <- n1last - natrail cbind(na_count_between_1st_last_num=n1num, na_count_between_1st_num_last_row=n1last)

output:

na_count_between_1st_last_num na_count_between_1st_num_last_row x 0 2 y 1 1 z 2 2 a 1 2 b 0 0 d 0 1

data:

df <- data.frame(x=c(7,8,NA,NA), #0 2 y=c(NA, 2, NA, 4), #1 1 z=c(4, NA, NA, 6), #2 2 a=c(1, NA, 1, NA), #1 2 b=c(NA, NA, 1, 1), #0 0 d=c(NA, 1, 1, NA)) #0 1

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**Excel COUNT and COUNTA functions with formula examples,** So let's take a quick look at these essential functions first, and then I will The COUNTA function in Excel counts the number of cells in a range� Algorithm to find first and last digits of a number. Get least significant digit of number (number%10) and store it in lastDigit variable. Remove least significant digit form number (number = number/10). Repeat above two steps, till number is greater than 10. The remaining number is the first digit of number.

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##### Comments

- On my real data, I get the output as # A tibble: 1 x 2 vars
`<NA>`

<chr> <int> 1 NA 0 , not sure why. Is it because of the names_pattern = "^(.)_(.*)$" - probabily because of
`names_pattern`

. Best check`?pivot_longer`

to see how to use`names_pattern`

. Maybe you can simply use`names_pattern = "^(.*)_(.*)$"`

.