Data frame typecasting entire column to character from numeric

Question

Suppose I have a data.frame that\'s completely numeric. If I make one entry of the first column a character (for example), then the entire

Answer 1

You are allowed to have vectors of type list in a data.frame, and the list can contain any type of object except functions as long as it is of the same length as the other columns in the data.frame, e.g.:

mydataframe <- data.frame(numbers=1:3)
mydataframe$mylist <- list(1, 'plum', 5)
mydataframe
#  numbers mylist
#1       1      1
#2       2   plum
#3       3      5
sapply(mydataframe, typeof)
#  numbers    mylist 
#"integer"    "list" 
sapply(mydataframe$mylist, typeof)
#[1] "double"    "character" "double"  

Answer 2

Short answer is you cannot.
As was mentioned in the comments, in a data frame, all elements of a column must have the same mode.

If you would like to specifically find the values that are "number like" you can use the following (where vec here would be, say, a data frame column)

  vec[!is.na(as.numeric((vec)))]

You can then convert these, but unfortunately you cannot put the converted values back into the same column. As as you do, they will be coerced back to character

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As for a function that can convert the whole dataframe to numeric (realizing that isolating specific entries as exceptions is not possible), you can use sapply

  sapply(dataFrameName, as.numeric)