R - How to determine if every value in column of dataframe is zero?

Question

I have a dataframe and want to determine for a given column if every value in the column is equal to zero.

This is the code I have:

z <- read.zoo(sub, sep = ",", header = TRUE, index = 1:2, tz = "", format = "%Y-%m-%d %H:%M:%S")

if(all.equal(z$C_duration, 0)) 
  C_dur_acf = NA

But I am getting an error:

 Error in if (all.equal(z$C_duration, 0)) { : 
  argument is not interpretable as logical

The code should return a boolean value (TRUE/FALSE) if the entire column is all zeros.

Welcome to SO. First of all you should read [here](http://stackoverflow.com/help/how-to-ask) about how to ask a good question; a good question has better chances to be solved and you to receive help. On the other hand a read of [this](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) is also good. It explains how to create a reproducible example in R. Help users to help you by providing a piece of your data a desired output and things you have tried so far. — SabDeM, Oct 24 '16 at 21:04
@G.Grothendieck Yes you're right. In this case I don't believe it matters because dataframe and zoo object columns can be indexed in the same manner using the '$' operator — T.Grover, Oct 24 '16 at 23:31

score 12 · Accepted Answer · answered Oct 24 '16 at 21:01

12

Use all builtin: all(z$C_duration == 0)

answered Oct 24 '16 at 21:01

Steves

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Great! Thank you! This was exactly what I needed and the most simple solution here. – T.Grover Oct 24 '16 at 21:43

SabDeM · Answer 2 · 2016-10-24T21:07:37.513

3

Here is an example by using the iris dataset built in R and apply function in addiction with all that allows you to test if all elements of the objects you pass in it do respect one or more logical conditions.

Do note that in this case the "objects" is a column of the data frame. The code with lapply do the same for every column.

lapply(iris[-5], function(x) all(x == 0))
$Sepal.Length
[1] FALSE

$Sepal.Width
[1] FALSE

$Petal.Length
[1] FALSE

$Petal.Width
[1] FALSE

edited Oct 24 '16 at 21:07

answered Oct 24 '16 at 20:59

SabDeM

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T. Grover wants to check if everything is equal to zero, not greater than or equal zero, but otherwise this answer is great. – Eli Sadoff Oct 24 '16 at 21:00
1

@EliSadoff, I know. OP would provide a piece of data to avoid users to use build in datasets. – SabDeM Oct 24 '16 at 21:03
I completely missed that. Sorry! – Eli Sadoff Oct 24 '16 at 21:06

score 0 · Answer 3 · answered Oct 24 '16 at 21:15

0

To use all.equal:

if(all.equal(z$C_duration, rep(0, length(z$C_duration)){
    C_dur_acf = NA
}

In essence all.equal does a pair-wise test. The if statement is failing because all.equal(z$C_duration,0) returns: "Numeric: lengths (##, 1) differ"

HTH!

answered Oct 24 '16 at 21:15

emilliman5

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R - How to determine if every value in column of dataframe is zero?

3 Answers3