adding rows

[pandeyravi15]

Can not we use rbind function as cbind , like newRow <- c("tortoiseshell", 3.3, TRUE, 9) instead of list

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[zyqfrog10]

Yes. You can use vector instead of list. The following code will add a new row as in the instruction.

newRow <- c("tortoiseshell", 3.3, TRUE, 9)
levels(cats$coat) <- c(levels(cats$coat), "tortoiseshell")
cats <- rbind(cats, newRow)

[jcoliver]

Thanks @pandeyravi15 and @zyqfrog10 . Using a vector to add a new row to a data frame will not work as intended. This is because all elements of a vector must be of the same type. When the vector newRow is declared, it coerces every element to be of type character (this occurs without any messaging). Additionally, when that vector is added to the data frame via rbind, all columns in the data frame are then coerced to be of type character. This also occurs without any warnings or errors from R, so it seems like it worked. Running summary before and after the addition of newRow illustrates this behavior:

cats <- data.frame(coat = c("calico", "black", "tabby"), 
                    weight = c(2.1, 5.0,3.2), 
                    likes_string = c(TRUE, FALSE, TRUE))
summary(cats) # The three columns are type factor, float, and logical
#     coat       weight      likes_string   
# black :1   Min.   :2.100   Mode :logical  
# calico:1   1st Qu.:2.650   FALSE:1        
# tabby :1   Median :3.200   TRUE :2        
#            Mean   :3.433                  
#            3rd Qu.:4.100                  
#            Max.   :5.000                  

newRow <- c("tortoiseshell", 3.3, TRUE, 9)
levels(cats$coat) <- c(levels(cats$coat), "tortoiseshell")
cats <- rbind(cats, newRow)
summary(cats) # weight and likes_string are now type character
#            coat      weight          likes_string      
# black        :1   Length:4           Length:4          
# calico       :1   Class :character   Class :character  
# tabby        :1   Mode  :character   Mode  :character  
# tortoiseshell:1

By using a list, we preserve the type of each of the elements (factor, float, and logical, respectively).