Hi,
Thank you! It was indeed a character :) I used
my_data$Sampling <- as.factor(my_data$Sampling)
and now it works:
[1] "Dec17" "Jan18" "Jun18" "Mar18" "May18" "Nov18" "Oct17" "Sep18"
Kr,
Vesna
From: Torsten Hauffe <torsten.hauffe at gmail.com>
Sent: Tuesday, June 23, 2020 6:06 PM
To: Vesna Gulin <vesna.gulin at biol.pmf.hr>
Cc: r-sig-ecology at r-project.org
Subject: Re: [R-sig-eco] LEVELS function NULL
Hi,
What is the output of
class(my_data$Sampling)?
If it is not factor (but character), you could write
my_data$Sampling <- as.factor(my_data$Sampling)
Then levels(my_data$Sampling) should return Sep18 etc.
Cheers!
On Tue, Jun 23, 2020 at 6:00 PM Vesna Gulin <vesna.gulin at biol.pmf.hr
<mailto:vesna.gulin at biol.pmf.hr> > wrote:
Hi everyone,
It has been a couple months now of using R and I am slowly trying to switch
from using Statistica to R in order to process my data (for PhD purposes).
I did some basic statistics and now I would like to try Kruskal-Wallis
(following this guideline:
http://www.sthda.com/english/wiki/kruskal-wallis-test-in-r )
but I have been stuck for days as I can't seem to find a reason why the
levels function keeps giving me NULL.
My data is a data frame:
my_data
Temperature Sampling
1 9.90 Dec17
2 10.00 Dec17
3 10.00 Dec17
4 10.10 Dec17
5 9.90 Dec17
6 10.10 Dec17
7 10.20 Dec17
8 10.10 Jan18
9 10.50 Jan18
10 10.80 Jan18
11 10.30 Jan18
12 10.30 Jan18
13 10.20 Jan18
14 10.50 Jan18
15 20.90 Jun18
16 20.80 Jun18
17 20.50 Jun18
18 20.50 Jun18
19 20.70 Jun18
20 20.60 Jun18
21 20.50 Jun18
22 10.50 Mar18
23 11.40 Mar18
24 10.90 Mar18
25 10.60 Mar18
26 11.60 Mar18
27 11.20 Mar18
28 12.20 Mar18
29 19.40 May18
30 19.00 May18
31 20.80 May18
32 19.50 May18
33 18.60 May18
34 18.10 May18
35 19.20 May18
36 16.80 Nov18
37 16.50 Nov18
38 18.40 Nov18
39 18.10 Nov18
40 16.70 Nov18
41 16.70 Nov18
42 18.50 Nov18
43 15.50 Oct17
44 15.10 Oct17
45 15.00 Oct17
46 15.80 Oct17
47 15.20 Oct17
48 15.10 Oct17
49 15.20 Oct17
50 23.40 Sep18
51 24.05 Sep18
52 23.70 Sep18
53 23.40 Sep18
54 24.05 Sep18
55 23.80 Sep18
56 24.15 Sep18
When I hit levels(my_data$Sampling) it gives me
NULL
I would very much appreciate any help.
Kind regards,
Vesna
Vesna Gulin, Research Assistant
Department of Biology
Faculty of Science
University of Zagreb
Rooseveltov trg 6, 10000 Zagreb, Croatia
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