Faculty of Agrobiotechnical Sciences Osijek and Agricultural Institute Osijek
Abstract
Visualization of multivariate multidimensional data sets is a challenging task, especially without use of adequate tools and methods. In the last few years, parallel coordinate plots became quite popular and accepted as a very efficient multivariate visualization technique. The aim of this paper was to explore how parallel coordinates can be used in analysis of winter wheat quantitative traits. Data set is obtained from experiment set up by a completely randomized design with two treatments and four replicates. Ten variables (plant height, spike length, stem length, plant weight, spike weight, grain weight per spike, 1000 kernel weight, number of fertile and sterile spikelets per spike and total number of spikelets per spike) and fifty-five winter wheat genotypes were analysed in this paper. In parallel coordinate plots observations are shown as series of unbroken lines, passing through parallel axes, where each axes represents a different variable. Advantage of parallel coordinates, compared to other visualization techniques, is that they can represent multivariate data in two dimensions. From such representation, outliers and grouping among observations are easily detectable. Correlation among variables can also be easily detected from suchrepresentation. Although parallel coordinates cannot efficiently explore details, they are a good technique for visualization of multivariate data sets and they can be used for exploratory analysis of wheat quantitative traits.Grafički prikazati multivarijantno-multidimenzionalni skup podataka bez primjene odgovarajućih alata nije jednostavan posao. U posljednjih nekoliko godina porasla je popularnost paralelnih koordinata, koje su se pokazale kao vrlo učinkovita metoda za vizualizaciju. Cilj ovoga rada bio je istražiti mogućnosti primjene paralelnih koordinata pri ispitivanju kvantitativnih svojstava ozime pšenice. U radu su korišteni podaci iz pokusa postavljenoga po potpuno slučajnome planu, s dva tretmana u četiri ponavljanja. U radu je analizirano deset varijabli (visina biljke, duljina stabljike, duljina klasa, masa biljke, masa klasa, masa zrna po klasu, masa 1000 zrna, broj sterilnih i fertilnih klasića, i ukupan broj klasića po klasu) i pedeset pet genotipova ozime pšenice. U dijagramu paralelnih koordinata opservacije su prikazane kao linije koje prolaze kroz paralelne osi, a svaka os predstavlja jednu varijablu. Prednost paralelnih koordinata, u odnosu na druge vizualizacijske metode, je u tome što multidimenzionalne probleme prikazuje u dvije dimenzije te se u takvome prikazu mogu lako uočiti odstupanja i grupiranja pojedinih opservacija te korelaciju među varijablama. Iako paralelne koordinate ne mogu otkriti i istražiti detalje promatranoga skupa, vrlo su korisne u vizualizaciji i eksploraciji multivarijantnih podataka, kao što su kvantitativna svojstva ozime pšenice
