group_by function

[fary]

hello everybody.
I know it is a stupid question but I can't find where is the mistake.
i am running these lines of code

df%>%
  select(BMI, Gender)%>%
  filter(Gender== "Male" |
             Gender == "Female")%>%
  group_by(Gender)%>%
  summarise(average_BMI = mean(BMI))

but I get this result:

average_BMI
1 NaN

[FJCC]

The NaN result will happen if one of your BMI values is NaN. Try running this code

NewDF <- df%>%
  select(BMI, Gender)%>%
  filter(Gender== "Male" | Gender == "Female")

and then run summary(NewDF). Does the summary of the BMI column say it has any NA's? If so, add na.rm = TRUE to your calculations of the mean.

mean(BMI, na.rm = TRUE)