R Newbie…calculating averages

0

I'm very new to R and I'm still quite close to the bottom of the very steep learning curve I think. So...

I have a data frame (imported from a .csv file). Contains a number of fields - let's call them Field1, Field2, Field3... Field 10.

The fields are numeric. For each row of data I'd like to calculate the average of the lowest 3 (say) numbers. In other words:

((smallest number) + (second smallest number) + (third smallest number))/3

Also there are some NAs in the data so I'd like the calculation to return NA if there aren't actually three numbers to avarage over (although perhaps R will do this naturally anyway).

Is there a succinct way to do this in R and (better still) to store the result as a new field in the existing data frame?

Grateful for any advice.
Thanks.
A

r dataframe calculated-columns

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edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

add a comment | 

0

I'm very new to R and I'm still quite close to the bottom of the very steep learning curve I think. So...

I have a data frame (imported from a .csv file). Contains a number of fields - let's call them Field1, Field2, Field3... Field 10.

The fields are numeric. For each row of data I'd like to calculate the average of the lowest 3 (say) numbers. In other words:

((smallest number) + (second smallest number) + (third smallest number))/3

Also there are some NAs in the data so I'd like the calculation to return NA if there aren't actually three numbers to avarage over (although perhaps R will do this naturally anyway).

Is there a succinct way to do this in R and (better still) to store the result as a new field in the existing data frame?

Grateful for any advice.
Thanks.
A

r dataframe calculated-columns

share|improve this question

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

add a comment | 

0

0

0

1

I'm very new to R and I'm still quite close to the bottom of the very steep learning curve I think. So...

I have a data frame (imported from a .csv file). Contains a number of fields - let's call them Field1, Field2, Field3... Field 10.

The fields are numeric. For each row of data I'd like to calculate the average of the lowest 3 (say) numbers. In other words:

((smallest number) + (second smallest number) + (third smallest number))/3

Also there are some NAs in the data so I'd like the calculation to return NA if there aren't actually three numbers to avarage over (although perhaps R will do this naturally anyway).

Is there a succinct way to do this in R and (better still) to store the result as a new field in the existing data frame?

Grateful for any advice.
Thanks.
A

r dataframe calculated-columns

share|improve this question

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

I'm very new to R and I'm still quite close to the bottom of the very steep learning curve I think. So...

I have a data frame (imported from a .csv file). Contains a number of fields - let's call them Field1, Field2, Field3... Field 10.

The fields are numeric. For each row of data I'd like to calculate the average of the lowest 3 (say) numbers. In other words:

((smallest number) + (second smallest number) + (third smallest number))/3

Also there are some NAs in the data so I'd like the calculation to return NA if there aren't actually three numbers to avarage over (although perhaps R will do this naturally anyway).

Is there a succinct way to do this in R and (better still) to store the result as a new field in the existing data frame?

Grateful for any advice.
Thanks.
A

r dataframe calculated-columns

r dataframe calculated-columns

share|improve this question

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

share|improve this question

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

share|improve this question

share|improve this question

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

edited Nov 19 '18 at 20:22

Daniel A. White

148k36293372

148k36293372

asked Nov 19 '18 at 20:21

AlanAlan

306

asked Nov 19 '18 at 20:21

AlanAlan

306

asked Nov 19 '18 at 20:21

AlanAlan

306

306

add a comment | 

add a comment | 

2 Answers
2

active

oldest

votes

0

For each row of data I'd like to calculate the average of the lowest 3 (say) numbers.

I think this should achieve what you're asking:

data <- mtcars

data$low.mean <- apply(data, 1, function(x) mean(head(sort(x[!is.na(x)]), n = 3)))

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

add a comment | 

0

 data(mtcars) 



 avg3 <- sapply(mtcars, function(x) mean(head(sort(x[!is.na(x)]), 3))) 



 avg3



 mtcars.avg3 <- rbind(mtcars, avg3) 



 mtcars.avg3

share|improve this answer

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
  – mickey
  Nov 19 '18 at 20:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks @mickey, good point
  – paoloeusebi
  Nov 19 '18 at 21:02
  

  
  
  
  

add a comment | 

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

active

oldest

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votes

0

For each row of data I'd like to calculate the average of the lowest 3 (say) numbers.

I think this should achieve what you're asking:

data <- mtcars

data$low.mean <- apply(data, 1, function(x) mean(head(sort(x[!is.na(x)]), n = 3)))

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

add a comment | 

0

For each row of data I'd like to calculate the average of the lowest 3 (say) numbers.

I think this should achieve what you're asking:

data <- mtcars

data$low.mean <- apply(data, 1, function(x) mean(head(sort(x[!is.na(x)]), n = 3)))

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

add a comment | 

0

0

0

For each row of data I'd like to calculate the average of the lowest 3 (say) numbers.

I think this should achieve what you're asking:

data <- mtcars

data$low.mean <- apply(data, 1, function(x) mean(head(sort(x[!is.na(x)]), n = 3)))

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

For each row of data I'd like to calculate the average of the lowest 3 (say) numbers.

I think this should achieve what you're asking:

data <- mtcars

data$low.mean <- apply(data, 1, function(x) mean(head(sort(x[!is.na(x)]), n = 3)))

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

share|improve this answer

share|improve this answer

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

answered Nov 19 '18 at 20:47

alexjacksonalexjackson

221

221

add a comment | 

add a comment | 

0

 data(mtcars) 



 avg3 <- sapply(mtcars, function(x) mean(head(sort(x[!is.na(x)]), 3))) 



 avg3



 mtcars.avg3 <- rbind(mtcars, avg3) 



 mtcars.avg3

share|improve this answer

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
  – mickey
  Nov 19 '18 at 20:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks @mickey, good point
  – paoloeusebi
  Nov 19 '18 at 21:02
  

  
  
  
  

add a comment | 

0

 data(mtcars) 



 avg3 <- sapply(mtcars, function(x) mean(head(sort(x[!is.na(x)]), 3))) 



 avg3



 mtcars.avg3 <- rbind(mtcars, avg3) 



 mtcars.avg3

share|improve this answer

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
  – mickey
  Nov 19 '18 at 20:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks @mickey, good point
  – paoloeusebi
  Nov 19 '18 at 21:02
  

  
  
  
  

add a comment | 

0

0

0

 data(mtcars) 



 avg3 <- sapply(mtcars, function(x) mean(head(sort(x[!is.na(x)]), 3))) 



 avg3



 mtcars.avg3 <- rbind(mtcars, avg3) 



 mtcars.avg3

share|improve this answer

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

 data(mtcars) 



 avg3 <- sapply(mtcars, function(x) mean(head(sort(x[!is.na(x)]), 3))) 



 avg3



 mtcars.avg3 <- rbind(mtcars, avg3) 



 mtcars.avg3

share|improve this answer

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

share|improve this answer

share|improve this answer

edited Nov 19 '18 at 21:00

edited Nov 19 '18 at 21:00

edited Nov 19 '18 at 21:00

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

answered Nov 19 '18 at 20:36

paoloeusebipaoloeusebi

641413

641413

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
  – mickey
  Nov 19 '18 at 20:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks @mickey, good point
  – paoloeusebi
  Nov 19 '18 at 21:02
  

  
  
  
  

add a comment | 

• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
  – mickey
  Nov 19 '18 at 20:47
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  Thanks @mickey, good point
  – paoloeusebi
  Nov 19 '18 at 21:02
  

  
  
  
  

1

1

Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
– mickey
Nov 19 '18 at 20:47

Maybe change sort(x[!is.na(x)] )[1:3]) to head(sort(x[!is.na(x)]), 3) for the case that removing the NAs gives less than 3 results.
– mickey
Nov 19 '18 at 20:47

Thanks @mickey, good point
– paoloeusebi
Nov 19 '18 at 21:02

Thanks @mickey, good point
– paoloeusebi
Nov 19 '18 at 21:02

add a comment | 

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