Add frequency and SD to a summary in R [duplicate]

问题

I have a data.frame like this (example):

product   protein   fat   starch
  aaa        40      5      10
  bbb        50      6      8
  ccc        12      50     4

and I want to ask for a summary of this values (min,max,1stQ, 3rdQ..). When I run:

aggregate(protein~product,summary,data=DATA4, na.rm = TRUE)

I have this...

    product protein.Min. protein.1st Qu. protein.Median protein.Mean protein.3rd Qu. protein.Max.
      aaa        6.400          14.700         15.600       15.540          16.600       22.500
      bbb        6.300           9.400         10.100       10.130          10.800       15.100
      ccc       23.000          24.080         24.250       24.180          24.420       25.000

However I also wanted to have the frequency and SD. How can I ask that? I tried with ddply but i cannot make it works. (I have NA's in some variables(protein, fat, starch...)

Besides this, and because here i'm only asking a summary for protein levels, how can I ask a summary for every variables that I have (protein, fat, starch, etc...) all in once?

Thank you very much!

回答1:

If I want to specify how I get the output of a summary I usually turn to a more elaborate solution using dplyr like so:

library(dplyr)

df <- data.frame(product = rep(letters[1:3], each=3,3),
                 protein = sample(10:40, 27, replace=T))

df %>% group_by(product) %>% 
  summarise(min = min(protein)
            ,max = max(protein)
            ,mean = mean(protein)
            ,sd = sd(protein)
            ,n = n()
            ,q25 = quantile(protein, .25)
            ,q75 = quantile(protein, .75))

result:

# A tibble: 3 × 8
  product   min   max     mean       sd     n   q25   q75
   <fctr> <int> <int>    <dbl>    <dbl> <int> <dbl> <dbl>
1       a    16    39 24.66667 8.717798     9    17    30
2       b    24    40 31.55556 5.387743     9    26    35
3       c    13    38 26.66667 8.108637     9    22    31

来源：https://stackoverflow.com/questions/42004912/add-frequency-and-sd-to-a-summary-in-r

标签

frequency

summary