Creating a counter in R using a loop

Question

I am a beginner at R and searched the forums and did not find an answer to this question. I am trying to create a loop in R that counts whether a condition is met between 2 rows in a dataframe. I understand that this is not an efficient way to do this but it is for a class assignment. My problem is that my code is creating an endless loop rather giving me the counter output and it is unclear to me how to fix it. I would greatly appreciate any suggestion. The code is below:

counter=0
for (i in 1:nrow(dataframe))
  {if (dataframe$column1[i]>dataframe$column2[i]==TRUE)
{
counter=counter+1}
}
print(counter)

There's nothing obviously wrong with the code, but it would be helpful if you could share the dataframe as well. — Andrew Gustar
– Andrew Gustar, Commented Mar 25, 2017 at 17:10

Smich7 · Accepted Answer · 2017-03-27 10:09:20Z

1

If you just want to know how many times your column 1 is higher than column 2, you don't have to use a loop :

counter <- sum(dataframe$column1>dataframe$column2)

sum(dataframe$column1>dataframe$column2) gives you a vector of length nrow(dataframe) with TRUE and FALSE when the condition is verified, and R do this element by element with vectores.

Then when you sum it, TRUE is considered as a 1 and FALSE as a 0. So it gives you how many times the condition is verified beetween the two columns.

edited Mar 27, 2017 at 10:09

answered Mar 25, 2017 at 17:11

Smich7

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1 Comment

learningcompsci Over a year ago

I appreciate the concise solution using the sum command but I need to do this assignment using control flow which is why I was using a loop. The columns in the dataframe that I am referencing have both numbers and empty values. I modified the code above by putting a print(counter) statement in the line below the counter =counter+1 but when I run the loop I get no output rather than the current counter. It is unclear to me what I am doing wrong so would greatly appreciate any additional suggestions

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