Using custom R functions and map, map_dfr, and map2 to create multiple ROC curves (CC123)

[@Riffomonas]

What questions do you have about writing your own functions in R? How about questions for using purrr's map functions?

[@nastassiashkliarava974]

Hi. Very cool video, informative. There is a question, what is meant here by set.seed(). Thank you

[@Riffomonas]

​@@nastassiashkliarava974 Hi Nastassia! If I recall correctly... The placement of the data on the x-axis within each group is random with geom_jitter. The set.seed function makes a random process reproducible. By setting the seed to a constant value, the random numbers generated by the random number generator will be the same each time the script is run. Try running set.seed(1); runif(10); runif(10). You'll see that the second 10 numbers are different from the first. But if you run set.seed(1); runif(10) the 10 numbers will be the same as the first 10

[@nastassiashkliarava974]

@@Riffomonas Yeah, so set.seed() I can take any number? Well, then you can somehow tell me about clustering and how to do it better, otherwise, there are so many questions. Thank you so much

[@Riffomonas]

@@nastassiashkliarava974 That's right - it can take any number. Talking about clustering is beyond the scope of what I can do in these comment threads :) If you're asking about clustering 16S rRNA gene sequences, then I'd encourage you to check out my past papers and consider taking the next mothur workshop riffomonas.org/workshops/

[@sancaixie1750]

Thanks for creating so many very informative R tutorials! I am also interesting in reading your results, especially in Porphyromonas and peptostreptococcus genera, which are associated with periodontitis. Have you published the results you are discussing in this video?

[@hansmeiser6078]

It's the first time in 6 years, that I heard of an index-option in map_dfr(1:2,...). I found nothing about it in the docs. Where can I get the full parameter-list of the map functions? By the way... this works: sampleDf

[@Riffomonas]

Thanks for watching! Here's the documentation page for the map functions: purrr.tidyverse.org/reference/map.html

[@hansmeiser6078]

@@Riffomonas Thank you, but they dont mention the run index (1:2). Where did you got this information?

[@Riffomonas]

@@hansmeiser6078 Sorry it's been a while since I made this video so I'm not able to find where I did run index (1:2). The first slot in the map functions defaults to the .x argument. So if we did .x=1:2 we would be giving it a vector of values. The resason your map2 function wouldn't work is because you are setting .x and .y, which are the first two arguments to the function. I suspect it might think 1:2 is the function that you are trying to execute rather than the ~doRoll