[R-sig-eco] LEVELS function NULL

[Torsten Hauffe]

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 using 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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>
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