Wrong result of mean with dplyr

Question

I am a beginner in R and I have a big data.frame (more than 300000 obs) that look like this:

Dados <- data.frame(stringsAsFactors=FALSE,
               id = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L, 9L, 10L, 11L, 12L, 13L,
                      14L, 15L, 16L, 17L, 18L, 19L, 20L, 21L, 22L, 23L, 24L,
                      25L, 26L, 27L, 28L, 29L, 30L, 31L, 32L, 33L, 34L, 35L, 36L,
                      37L, 38L, 39L, 40L, 41L, 42L, 43L, 44L, 45L, 46L, 47L, 48L,
                      49L, 50L, 51L, 52L, 53L, 54L, 55L, 56L, 57L, 58L, 59L, 60L,
                      61L, 62L, 63L, 64L, 65L, 66L, 67L, 68L, 69L, 70L, 71L,
                      72L, 73L, 74L, 75L, 76L, 77L, 78L, 79L, 80L, 81L, 82L, 83L,
                      84L, 85L, 86L, 87L, 88L, 89L, 90L, 91L, 92L, 93L, 94L, 95L,
                      96L, 97L, 98L, 99L, 100L, 101L, 102L, 103L, 104L, 105L,
                      106L, 107L, 108L, 109L, 110L, 111L, 112L, 113L, 114L, 115L,
                      116L, 117L, 118L, 119L, 120L, 121L, 122L, 123L, 124L, 125L,
                      126L, 127L, 128L, 129L, 130L, 131L, 132L, 133L, 134L, 135L,
                      136L, 137L, 138L, 139L, 140L, 141L, 142L, 143L),
   Identification = "LONNIE POOL FIELD WEAVERVILLE",
            Dates = c("1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014", "1/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014", "2/01/2014",
                      "2/01/2014", "2/01/2014", "2/01/2014"),
     TEMP_Celcius = c(13L, 10L, 8L, 7L, 5L, 4L, 3L, 3L, 2L, 2L, 2L, 2L, 0L, 0L,
                      0L, 0L, 0L, 0L, 0L, 0L, -1L, -1L, -2L, -1L, -2L, -2L,
                      -2L, -2L, -2L, -2L, -2L, -2L, -3L, -3L, -3L, -3L, -3L, -3L,
                      -3L, -3L, -4L, -4L, -3L, -4L, -4L, -4L, -4L, -4L, -4L, -3L,
                      -3L, -2L, 0L, 1L, 2L, 3L, 4L, 6L, 6L, 8L, 9L, 9L, 10L, 11L,
                      12L, 12L, 12L, 12L, 13L, 13L, 13L, 13L, 12L, 10L, 9L, 8L,
                      6L, 5L, 5L, 4L, 4L, 3L, 3L, 2L, 2L, 2L, 2L, 0L, 1L, 0L, 0L,
                      0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, -1L, -1L, -1L, -2L, -2L,
                      -1L, -2L, -2L, -2L, -2L, -2L, -2L, -2L, -2L, -3L, -3L, -3L,
                      -3L, -3L, -3L, -3L, -3L, -2L, -2L, 0L, 0L, 1L, 3L, 4L, 5L,
                      6L, 7L, 8L, 9L, 10L, 10L, 12L, 13L, 13L, 13L, 13L, 14L, 14L,
                      14L))

And I need to get others columns, like average temp, min, max, and average dew point max and min each per day. I have many results per day because it is hourly. I tried many ways but I am getting a wrong result.

First I tried to get the mean with this code:

tapply (Dados$TEMP_Celcius, Dados$Dates, mean) But I get wrong result. For example for the date 01-01-2014 I get 27.8 and the right result would be 1.97.

I tried either the codes:

tapply(Dados$TEMP_Celcius, Dados$Dates, mean, na.rm = TRUE)

aggregate(Dados$TEMP_Celcius, by=list(TMEDIA=Dados$Dates), mean)

But I got the same results. I do not know what I am doing wrong, could you help me please?

I already checked the class of the column Dates and it is "Date" and of teh variable temperature and it is "numeric".

Welcome, it will be easier for everyone to answer the question if you provide a reproducible example. — william3031, Mar 17 '19 at 21:12
Also, your example image doesn't load, but you should provide code instead of an image anyway. — william3031, Mar 17 '19 at 21:13
Use `dput()`. See here: https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example — william3031, Mar 17 '19 at 21:46
You can also just paste a sample of your data instead of the whole thing. Just enough so that we can work out what columns are needed to do what you want it to do. — william3031, Mar 17 '19 at 21:55
I tried to paste the first date of the data.frame. See if this will work please? When I past it the configuration seems to change. I would like to attaches a file with a sample of the data frame. Is it possible? — Ana Paula Franzoni, Mar 17 '19 at 22:27
The way that you have pasted it isn't useful. Can you use `dput()` or `dump()` as described here: https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example — william3031, Mar 17 '19 at 23:58
I am sorry, but I did not understand how to use the dput() or dump(). I am still trying. — Ana Paula Franzoni, Mar 18 '19 at 00:11
LIke this: `a <- dput(Dados)` `b <- structure(list .... #copy everything` — william3031, Mar 18 '19 at 00:17
The point of the requests to use `dput` are that it will give other people the ability to exactly recreate a sample of your data, formats and all. If your data frame is called `Dados` and you want to share the first 100 rows, you'd type `dput(head(Dados, 100))` into the console, and then paste the output of that into your question. — Jon Spring, Mar 18 '19 at 03:31
The current question is not working code. I would expect the actual output of `dput` to look substantially different -- for instance all the character fields would be in quotes. — Jon Spring, Mar 18 '19 at 03:36
Now I understand the dput()! Thank you Jon Spring and wl1234 for the help. I will make easier the next questions. — Ana Paula Franzoni, Mar 19 '19 at 04:10

william3031 · Answer 1 · 2019-03-18T05:50:53.927

Without actually seeing what data you have, perhaps you could try this? It uses the tidyverse (which you should learn as it will make everything much easier).

library(tidyverse)
Dados %>% 
  group_by(Dates) %>% 
  summarise(mean = mean(TEMP_Celcius), min = min(TEMP_Celcius), max = max(TEMP_Celcius))

This gave me this output:

# A tibble: 2 x 4
  Dates      mean   min   max
  <chr>     <dbl> <dbl> <dbl>
1 1/01/2014  1.97    -4    13
2 2/01/2014  2.75    -3    14

Updated after suggestion from @Jon Spring:

library(tidyverse)
Dados %>% 
  group_by(Identification, Dates) %>% 
  summarise(mean = mean(TEMP_Celcius), min = min(TEMP_Celcius), max = max(TEMP_Celcius))

Output:

# A tibble: 2 x 5
# Groups:   Identification [?]
  Identification                Dates      mean   min   max
  <chr>                         <chr>     <dbl> <dbl> <dbl>
1 LONNIE POOL FIELD WEAVERVILLE 1/01/2014  1.97    -4    13
2 LONNIE POOL FIELD WEAVERVILLE 2/01/2014  2.75    -3    14

Are there multiple locations in your data? If so, you should `group_by(Identification, Dates) %>%` in the code above, otherwise you will be getting the average of all locations on each day. — Jon Spring, Mar 18 '19 at 03:33
Works for me, see the results above. (Sorry, deleted comment accidently). — william3031, Mar 18 '19 at 03:34

Wrong result of mean with dplyr

1 Answers1