Hallo all
I found a strange problem for coding if part of list is NULL. In this case, sapply result is ***list of data frames*** but if there is no NULL leaf, the result is ***list of vectors***. I tried simplify option but it did not help me neither I found anything in help page. The code is part of bigger project where I fill list by reading in data and if it fails, the leaf is set to NULL. Then the the boxplot is created simply by boxplot(sapply(mylist2, "[", "b")) and the user is asked to select if values should be rbinded or not. Is it possible to perform some *apply without getting data frame as result in case NULL leaf? Here is an example (without boxplot) df1 <- data.frame(a=rnorm(5), b=runif(5), c=rlnorm(5)) df2 <- data.frame(a=rnorm(5), b=runif(5), c=rlnorm(5)) mylist1 <- list(df1,df2, df3) mylist2 <- list(NULL,df2, df3) > str(sapply(mylist1, "[", "b")) List of 3 $ b: num [1:5] 0.387 0.69 0.876 0.836 0.819 $ b: num [1:5] 0.01733 0.46055 0.19421 0.11609 0.00789 $ b: num [1:5] 0.593 0.478 0.299 0.185 0.847 > str(sapply(mylist2, "[", "b")) List of 3 $ : NULL $ :'data.frame': 5 obs. of 1 variable: ..$ b: num [1:5] 0.01733 0.46055 0.19421 0.11609 0.00789 $ :'data.frame': 5 obs. of 1 variable: ..$ b: num [1:5] 0.593 0.478 0.299 0.185 0.847 S pozdravem | Best Regards RNDr. Petr PIKAL Vedoucí Výzkumu a vývoje | Research Manager PRECHEZA a.s. nábř. Dr. Edvarda Beneše 1170/24 | 750 02 Přerov | Czech Republic Tel: +420 581 252 256 | GSM: +420 724 008 364 <mailto:petr.pi...@precheza.cz> petr.pi...@precheza.cz | <https://www.precheza.cz/> www.precheza.cz Osobní údaje: Informace o zpracování a ochraně osobních údajů obchodních partnerů PRECHEZA a.s. jsou zveřejněny na: <https://www.precheza.cz/zasady-ochrany-osobnich-udaju/> https://www.precheza.cz/zasady-ochrany-osobnich-udaju/ | Information about processing and protection of business partner's personal data are available on website: <https://www.precheza.cz/en/personal-data-protection-principles/> https://www.precheza.cz/en/personal-data-protection-principles/ Důvěrnost: Tento e-mail a jakékoliv k němu připojené dokumenty jsou důvěrné a podléhají tomuto právně závaznému prohlášení o vyloučení odpovědnosti: <https://www.precheza.cz/01-dovetek/> https://www.precheza.cz/01-dovetek/ | This email and any documents attached to it may be confidential and are subject to the legally binding disclaimer: <https://www.precheza.cz/en/01-disclaimer/> https://www.precheza.cz/en/01-disclaimer/
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