[R] alternative for multiple if_else statements

Kevin Wamae KWamae at kemri-wellcome.org
Mon Feb 26 14:12:46 CET 2018


Dear Ellison, thank you for the feedback, we replaced dplyr::if_else with dplyr::case_when and it seems to do the trick.

Still, we have to write several statements to match all the respective years but it's working.

Let me see how we can implement your suggestion.

Regards
------------------
Kevin Wamae
On 26/02/2018, 14:57, "S Ellison" <S.Ellison at LGCGroup.com> wrote:

    That many ifelse statements is obviously rather a pain.
    
    Would you not have got what you want with 
    
    ... paste("survey", year, sep="_") 
    ?
    
    If that is not what you're looking for (eg because 'year' is the observation year and not the study start year), perhaps something that picks the minimum year for a subject or other relevant group might work? For example
    paste("survey", ave(year, studyno, FUN=min), sep="_")
    
    
    S Ellison
    
    > -----Original Message-----
    > From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Kevin
    > Wamae
    > Sent: 21 February 2018 20:34
    > To: R-help at r-project.org
    > Subject: [R] alternative for multiple if_else statements
    > 
    > Hi, I am having trouble trying to figure out why if_else is behaving the way it is,
    > it may be my code or the way the data is structured.
    > 
    > Below is a snapshot of a database am working on and it represents a
    > longitudinal survey of study participants in a trial with weekly follow up.
    > 
    > The variable "survey_start" represents the start of the study-defined one year
    > follow up (which we called "survey_year").
    > 
    > I am trying to populate all subsequent entries for each participant, per survey
    > year, with the entry "survey" followed by an underscore and the respective
    > year, eg. survey_2014.
    > 
    > There are missing entries such as the participant represented here, wasn't
    > available at the start of the 2015 survey. Also, some participants don’t have
    > complete one-year follow ups but I still need to include them.
    > 
    > I have written two codes, first one fails while the second works, the only
    > difference being I have reversed the order in which the entries are populated in
    > the second code (from 2007-2016 to 2016-2007) and removed the if_else
    > statement for 2015. Also noticed, that for the second code, which spans the
    > years 2007-2016 (less 2015), if a participants entries start from 2010-2016, the
    > code fails.
    > 
    > Kindly assist in figuring this out...or better yet, an alternative.
    > 
    >     trialData <- structure(list(study = c("site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1", "site_1",
    > "site_1"), studyno = c("child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1", "child_1", "child_1", "child_1", "child_1", "child_1", "child_1",
    > "child_1"), date = structure(c(16078, 16085, 16092, 16098, 16104, 16115,
    > 16121, 16129, 16135, 16140, 16146, 16156, 16162, 16168, 16177, 16185,
    > 16191, 16195, 16203, 16210, 16217, 16225, 16234, 16237, 16246, 16253,
    > 16262, 16269, 16278, 16283, 16288, 16297, 16304, 16311, 16319, 16326,
    > 16332, 16337, 16346, 16353, 16360, 16366, 16370, 16381, 16384, 16395,
    > 16399, 16407, 16415, 16422, 16444, 16452, 16454, 16467, 16474, 16477,
    > 16484, 16490, 16501, 16508, 16514, 16520, 16529, 16533, 16539, 16550,
    > 16556, 16564, 16566, 16578, 16582, 16593, 16599, 16604, 16613, 16620,
    > 16623, 16635, 16636, 16654, 16660, 16666, 16673, 16681, 16688, 16693,
    > 16702, 16706, 16714, 16721, 16728, 16734, 16745, 16749, 16757, 16764,
    > 16769, 16778, 16785, 16792, 16805, 16812, 16819, 16830, 16832, 16839,
    > 16846, 16856, 16862, 16867, 16877, 16884, 16890, 16898, 16904, 16912,
    > 16917, 16923, 16936, 16938, 16953, 16960, 16966, 16973, 16980), class =
    > "Date"), year = c(2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L,
    > 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L,
    > 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L,
    > 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L,
    > 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2014L, 2015L, 2015L,
    > 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L,
    > 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L,
    > 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L,
    > 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L, 2015L,
    > 2015L, 2015L, 2015L, 2015L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L,
    > 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L,
    > 2016L, 2016L, 2016L, 2016L, 2016L, 2016L, 2016L), month = c(1L, 1L, 1L, 1L, 2L,
    > 2L, 2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 7L, 7L,
    > 7L, 7L, 8L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 10L, 10L, 10L, 10L, 10L, 11L, 11L, 11L,
    > 11L, 12L, 12L, 12L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L,
    > 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 9L, 10L,
    > 10L, 10L, 10L, 11L, 11L, 11L, 11L, 11L, 12L, 12L, 12L, 1L, 1L, 1L, 1L, 2L, 2L, 2L,
    > 2L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 6L), survey_start =
    > c("", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "Y", "", "", "", "", "", "", "",
    > "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    > "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    > "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "", "",
    > "", "", "", "", "", "", "", "Y", "", "", "", "", "", "", "", "", "", "", "", "", "", "")), class =
    > "data.frame", row.names = c(NA, -125L), .Names = c("study", "studyno", "date",
    > "year", "month",
    > "survey_start"))
    > 
    > 
    > code 1 fails:
    > 
    > trialData <- trialData %>% arrange(studyno, date) %>% group_by(studyno) %>%
    > mutate(survey_year = if_else(date >= date[survey_start == "Y" & year == 2007
    > & study == "site_1"][1] & date < date[month == 5 & year == 2008 & study ==
    > "site_1"][1], "survey_2007",
    >                      if_else(date >= date[survey_start == "Y" & year == 2008 & study
    > == "site_1"][1] & date < date[month == 4 & year == 2009 & study ==
    > "site_1"][1], "survey_2008",
    >                      if_else(date >= date[survey_start == "Y" & year == 2009 & study
    > == "site_1"][1] & date < date[month == 5 & year == 2010 & study ==
    > "site_1"][1], "survey_2009",
    >                      if_else(date >= date[survey_start == "Y" & year == 2010 & study
    > == "site_1"][1] & date < date[month == 5 & year == 2011 & study ==
    > "site_1"][1], "survey_2010",
    >                      if_else(date >= date[survey_start == "Y" & year == 2011 & study
    > == "site_1"][1] & date < date[month == 4 & year == 2012 & study ==
    > "site_1"][1], "survey_2011",
    >                      if_else(date >= date[survey_start == "Y" & year == 2012 & study
    > == "site_1"][1] & date < date[month == 4 & year == 2013 & study ==
    > "site_1"][1], "survey_2012",
    >                      if_else(date >= date[survey_start == "Y" & year == 2013 & study
    > == "site_1"][1] & date < date[month == 4 & year == 2014 & study ==
    > "site_1"][1], "survey_2013",
    >                      if_else(date >= date[survey_start == "Y" & year == 2014 & study
    > == "site_1"][1] & date < date[month == 4 & year == 2015 & study ==
    > "site_1"][1], "survey_2014",
    >                      if_else(date >= date[survey_start == "Y" & year == 2015 & study
    > == "site_1"][1] & date < date[month == 3 & year == 2016 & study ==
    > "site_1"][1], "survey_2015",
    >                      if_else(date >= date[survey_start == "Y" & year == 2016 & study
    > == "site_1"][1], "survey_2016","")))))))))))
    > 
    > code 2 works:
    > 
    >     trialData <- trialData %>% arrange(studyno, date) %>% group_by(studyno)
    > %>%
    >   mutate(survey_year = if_else(date >= date[survey_start == "Y" & year == 2016
    > & study == "site_1"][1]                                                               , "survey_2016",
    >                            if_else(date >= date[survey_start == "Y" & year == 2014 &
    > study == "site_1"][1] & date < date[month == 4 & year == 2015 & study ==
    > "site_1"][1], "survey_2014",
    >                            if_else(date >= date[survey_start == "Y" & year == 2013 &
    > study == "site_1"][1] & date < date[month == 4 & year == 2014 & study ==
    > "site_1"][1], "survey_2013",
    >                            if_else(date >= date[survey_start == "Y" & year == 2012 &
    > study == "site_1"][1] & date < date[month == 4 & year == 2013 & study ==
    > "site_1"][1], "survey_2012",
    >                            if_else(date >= date[survey_start == "Y" & year == 2011 &
    > study == "site_1"][1] & date < date[month == 4 & year == 2012 & study ==
    > "site_1"][1], "survey_2011",
    >                            if_else(date >= date[survey_start == "Y" & year == 2010 &
    > study == "site_1"][1] & date < date[month == 5 & year == 2011 & study ==
    > "site_1"][1], "survey_2010",
    >                            if_else(date >= date[survey_start == "Y" & year == 2009 &
    > study == "site_1"][1] & date < date[month == 5 & year == 2010 & study ==
    > "site_1"][1], "survey_2009",
    >                            if_else(date >= date[survey_start == "Y" & year == 2008 &
    > study == "site_1"][1] & date < date[month == 4 & year == 2009 & study ==
    > "site_1"][1], "survey_2008",
    >                            if_else(date >= date[survey_start == "Y" & year == 2007 &
    > study == "site_1"][1] & date < date[month == 5 & year == 2008 & study ==
    > "site_1"][1], "survey_2007",""))))))))))
    > 
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