CODEWITHSUNDEEP
rdataframegroup-bydplyr
anntree
anntree

Reputation: 271

Combining rows with the same value in one column and finding the mean value of those rows

I'm trying to combine rows in a dataframe called all_pdat whose head looks like this:

       diff_score    abserror
190          58 16.17851166
1140         58 12.55945835
2152         58 93.52071253
370          57 11.08828322
1142         57  0.07710115
230          56 90.87347961

What I would like to do is combine rows with the same diff_score value such that the abserror column reflects mean values of the combined rows. So the new df (pdat) head would look like this:

       diff_score    avg_error
190          58 40.7528941
370          57 5.58269218
230          56 90.87347961

I have tried the following, but it just gives me a df with a single row:

pdat <- all_pdat %>%
  group_by(diff_score) %>%
  summarise(avg_error = mean(abserror))

Thanks in advance.

Upvotes: 1

Views: 501

Answers (3)

akrun
akrun

Reputation: 887048

We can also use data.table

library(data.table)
setDT(df)[, .(absmeanerror = mean(abserror), diff_score]

Upvotes: 0

G.Fernandes
G.Fernandes

Reputation: 321

A way to do it would be using the by function, like this:

temp=by(all_pdat[,'abserror'],all_pdat[,'diff_Score'],mean)

pdat=data.frame('diff_score'=names(temp),'abserror'=c(temp)))

Upvotes: 0

Duck
Duck

Reputation: 39595

I would suggest a base R solution:

#Data
df <- structure(list(diff_score = c(58L, 58L, 58L, 57L, 57L, 56L), 
    abserror = c(16.17851166, 12.55945835, 93.52071253, 11.08828322, 
    0.07710115, 90.87347961)), class = "data.frame", row.names = c(NA, 
-6L))

The code:

dfn <- aggregate(abserror~diff_score,data=df,mean,na.rm=T)

Output:

  diff_score  abserror
1         56 90.873480
2         57  5.582692
3         58 40.752894

And the dplyr approach:

library(dplyr)
df %>% group_by(diff_score) %>% summarise(mean_abserror=mean(abserror))

Output:

# A tibble: 3 x 2
  diff_score mean_abserror
       <int>         <dbl>
1         56         90.9 
2         57          5.58
3         58         40.8

Maybe your issue is due to a conflict with other package.

Upvotes: 0

Related Questions