I have two columns col32_Dokh and col32_Pesa in a dataframe which contains "00", "01", ... Characters. I want to convert them to integer.
    df_integer <- transform(df_char, col32_Dokh = as.integer(col32_Dokh),
                                     col32_Pesa = as.integer(col32_Pesa))
but the conversion fails in this way:

 
    