Specifying colClasses in the read csv

Question

I am trying to specify the colClasses options in the read csv function in R  In my data  the first column  time  is basically a character vector while the rest of the columns are numeric   data  lt - read csv  test csv   comment char                        colClasses c time  character    numeric                      strip white FALSE    In the above command  I would want R to read in the  time  column as  character  and the rest as numeric  Although  the  data  variable did have the correct result after the command completed  R returned the following warnings  I am wondering how I could fix these warnings     Warning messages   1  In read table file   file  header   header  sep   sep  quote   quote         not all columns named in  colClasses  exist  2  In tmp i i  gt  0L    lt - colClasses       number of items to replace is not a multiple of replacement length   Derek

User · Answer

If you want to refer to names from the header rather than column numbers  you can use something like this   fname  lt -  test csv  headset  lt - read csv fname  header   TRUE  nrows   10  classes  lt - sapply headset  class  classes names classes   in  c  time     lt -  character  dataset  lt - read csv fname  header   TRUE  colClasses   classes

User · Answer

I know OP asked about the utils  read csv function  but let me provide an answer for these that come here searching how to do it using readr  read csv from the tidyverse   read csv   test csv   col names FALSE  col types   cols   default    c   time    i      This should set the default type for all columns as character  while time would be parsed as integer

User · Answer

You can specify the colClasse for only one columns   So in your example you should use   data  lt - read csv  test csv   colClasses c  time   character

User · Answer

Assuming your  time  column has at least one observation with a non-numeric character and all your other columns only have numbers  then  read csv s default will be to read in  time  as a  factor  and all the rest of the columns as  numeric   Therefore setting  stringsAsFactors F  will have the same result as setting the  colClasses  manually i e    data  lt - read csv  test csv   stringsAsFactors F

User · Answer

For multiple datetime columns with no header  and a lot of columns  say my datetime fields are in columns 36 and 38  and I want them read in as character fields   data lt -read csv  test csv   head FALSE    colClasses c  V36   character   V38   character

User · Answer

If we combine what  Hendy and  Oddysseus Ithaca contributed  we get cleaner and a more general  i e   adaptable   chunk of code       data  lt - read csv  test csv   head   F  colClasses   c V36    character   V38    character

User · Answer

The colClasses vector must have length equal to the number of imported columns  Supposing the rest of your dataset columns are 5   colClasses c  character  rep  numeric  5

[r] Specifying colClasses in the read.csv

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