[R] Calculating column differences

[Jeff Reichman]

Gerrit

 

Changed my approach 😊

 

df <- data.frame(ID=1:5,Score=4*2:6)

 

df %>% 

  mutate(score_diff = Score - lag(Score, default = 0))

 

Jeff

 

-----Original Message-----
From: R-help <r-help-bounces using r-project.org> On Behalf Of Gerrit Eichner
Sent: Wednesday, March 24, 2021 11:53 AM
To: r-help using r-project.org
Subject: Re: [R] Calculating column differences

 

Dear Jeff,

 

read diff's help page, and you'll find out what is wrong with your expectation.

 

What do think diff(df$Score) should give for the first element in df$Score??

 

  Hth  --  Gerrit

 

---------------------------------------------------------------------

Dr. Gerrit Eichner                   Mathematical Institute, Room 212

 <mailto:gerrit.eichner using math.uni-giessen.de> gerrit.eichner using math.uni-giessen.de   Justus-Liebig-University Giessen

Tel: +49-(0)641-99-32104          Arndtstr. 2, 35392 Giessen, Germany

 <http://www.uni-giessen.de/eichner> http://www.uni-giessen.de/eichner

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Am 24.03.2021 um 17:48 schrieb Jeff Reichman:

> r-help forum

> 

>   

> 

> I'm trying to calculate the diff between two rows and them mutate the 

> difference into a new column. I'm using the diff function but not 

> giving me what I want.

> 

>   

> 

> df <- data.frame(ID=1:5,Score=4*2:6)

> 

>   

> 

> What a want  where

> 

>    ID Score  diff

> 

> 1  1     8      8

> 

> 2  2    12     4

> 

> 3  3    16     4

> 

> 4  4    20     4

> 

> 5  5    24     4

> 

>   

> 

> What I am getting

> 

>    ID Score  diff

> 

> 1  1     8      NA

> 

> 2  2    12     4

> 

> 3  3    16     4

> 

> 4  4    20     4

> 

> 5  5    24     4

> 

>   

> 

> Jeff

> 

>   

> 

> 

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> 

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> and provide commented, minimal, self-contained, reproducible code.

> 



______________________________________________

 <mailto:R-help using r-project.org> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see  <https://stat.ethz.ch/mailman/listinfo/r-help> https://stat.ethz.ch/mailman/listinfo/r-help

PLEASE do read the posting guide  <http://www.R-project.org/posting-guide.html> http://www.R-project.org/posting-guide.html

and provide commented, minimal, self-contained, reproducible code.


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