How can I divide one column of a data frame through another

Question

I wanted to divide one column by another to get the per person time how can I do this?I couldn't find anything on how you can divide.

Here is some data that I want to use

     min    count2.freq
263807.0    1582
196190.5    1016
586689.0    3479

In the end I want to add a third column like this that has the number from min / count2.freq

e.g 263808.0/1582 = 166.75

User · Answer

Hadley Wickham      dplyr   packages is always a saver in case of data wrangling  To add the desired division as a third variable I would use mutate    d  lt - mutate d  new   min   count2 freq

User · Answer

There are a plethora of ways in which this can be done  The problem is how to make R aware of the locations of the variables you wish to divide   Assuming  d  lt - read table text    263807 0    1582 196190 5    1016 586689 0    3479    names d   lt - c  min    count2 freq    gt  d        min count2 freq 1 263807 0        1582 2 196190 5        1016 3 586689 0        3479   My preferred way  To add the desired division as a third variable I would use transform     gt  d  lt - transform d  new   min   count2 freq   gt  d        min count2 freq      new 1 263807 0        1582 166 7554 2 196190 5        1016 193 1009 3 586689 0        3479 168 6373   The basic R way  If doing this in a function  i e  you are programming  then best to avoid the sugar shown above and index  In that case any of these would do what you want     1  via     and character indexes d    new    lt - d    min     d    count2 freq       2  via     with numeric indices d   3   lt - d   1    d   2      3  via     d new  lt - d min   d count2 freq   All of these can be used at the prompt too  but which is easier to read   d  lt - transform d  new   min   count2 freq    or   d new  lt - d min   d count2 freq    or any of the above examples   Hopefully you think like I do and the first version is better  -   The reason we don t use the syntactic sugar of tranform   et al when programming is because of how they do their evaluation  look for the named variables   At the top level  at the prompt  working interactively  transform   et al work just fine  But buried in function calls or within a call to one of the apply   family of functions they can and often do break   Likewise  be careful using numeric indices     2  above   if you change the ordering of your data  you will select the wrong variables   The preferred way if you don t need replacement  If you are just wanting to do the division  rather than insert the result back into the data frame  then use with    which allows us to isolate the simple expression you wish to evaluate   gt  with d  min   count2 freq   1  166 7554 193 1009 168 6373   This is again much cleaner code than the equivalent   gt  d min   d count2 freq  1  166 7554 193 1009 168 6373   as it explicitly states that  using d  execute the code min   count2 freq  Your preference may be different to mine  so I have shown all options

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