R data.frame with 0 values

Question

My pos_TAT data frame contains 7 rows but the last one appears only when I do summary because its value is 0.

summary(pos_TAT)
Delayed$position.type  Delayed$TAT   
            JF     :1
           S20     :1
           S40     :1
           S60     :1
      Specials     :1
           S70     :1   
         14-19     :0



pos_TAT
  Delayed$position.type Delayed$TAT
1                    JF    45.10965
2                   S20    44.37831
3                   S40    44.18750
4                   S60    45.40698
5              Specials    43.30079
6                   S70    42.44444    

That poses problem if I want to add a column with the count for example as it tells me there's a different number of rows 6, 7.

I've spent hours looking into that problem but can't find the answer. Thank you.

Answer 1

This could be possible when there are unused levels for factor columns in the dataset. Either convert the column to character or if we need to keep it as factor class, then use droplevels or call factor again.

df2 <- droplevels(pos_TAT)

Or

df2 <- transform(pos_TAT, Delayed$position.type= as.character(Delayed$position.type))

---

The summary would also give the unused levels as the OP showed

summary(pos_TAT[1])
# Delayed$position.type
# JF      :1           
# S20     :1           
# S40     :1           
# S60     :1           
# Specials:1           
# S70     :1           
# 14-19   :0      

data

pos_TAT <- structure(list(`Delayed$position.type` = structure(1:6, .Label = c("JF", 
"S20", "S40", "S60", "Specials", "S70", "14-19"), class = "factor"), 
Delayed.TAT = c(45.10965, 44.37831, 44.1875, 45.40698, 43.30079, 
42.44444)), .Names = c("Delayed$position.type", "Delayed.TAT"
), row.names = c("1", "2", "3", "4", "5", "6"), class = "data.frame")