[R-sig-eco] LEVELS function NULL

[Vesna Gulin]

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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