How to get exclusive date ranges?

Question

I would like an object that gives me a date range for every month (or quarter) from 1990-01-01 to 2021-12-31, separated by a colon. So for example in the monthly case, the first object would be 1990-01-01:1990-01-31, the second object would be 1990-02-01:1990-02-31, and so on.

The issue I am having trouble with is making sure that the date range is exclusive, i.e., that no date gets repeated.

start_date1 <- as.Date("1990-01-01", "%Y-%m-%d")
end_date1 <- as.Date("2021-12-01", "%Y-%m-%d")
first_date <-  format(seq(start_date1,end_date1,by="month"),"%Y-%m-%d")

start_date2 <- as.Date("1990-02-01", "%Y-%m-%d")
end_date2 <- as.Date("2022-01-01", "%Y-%m-%d")
second_date <-  format(seq(start_date2,end_date2,by="month"),"%Y-%m-%d")

date<-paste0(first_date, ":")
finaldate<-paste0(date, second_date)

This code works, except that the first date in each month gets repeated "1990-01-01:1990-02-01" "1990-02-01:1990-03-01", and that the last date is "2021-12-01:2022-01-01" (including Jan 1, 2022 rather than stopping at Dec 31, 2021.

If I go by 30 days instead, it doesn't work as well because not every month has 30 days.

What's the best way to get an exclusive date range?

Answer 1

You could do:

dates <- seq(as.Date("1990-01-01"), as.Date("2022-01-01"), by = "month")
dates <- paste(head(dates, -1), tail(dates-1, - 1), sep = ":")

resulting in:

dates
#>   [1] "1990-01-01:1990-01-31" "1990-02-01:1990-02-28" "1990-03-01:1990-03-31"
#>   [4] "1990-04-01:1990-04-30" "1990-05-01:1990-05-31" "1990-06-01:1990-06-30"
#>   [7] "1990-07-01:1990-07-31" "1990-08-01:1990-08-31" "1990-09-01:1990-09-30"
#>  [10] "1990-10-01:1990-10-31" "1990-11-01:1990-11-30" "1990-12-01:1990-12-31"
#>  [13] "1991-01-01:1991-01-31" "1991-02-01:1991-02-28" "1991-03-01:1991-03-31"
#>  [16] "1991-04-01:1991-04-30" "1991-05-01:1991-05-31" "1991-06-01:1991-06-30"
#>  [19] "1991-07-01:1991-07-31" "1991-08-01:1991-08-31" "1991-09-01:1991-09-30"
#>  [22] "1991-10-01:1991-10-31" "1991-11-01:1991-11-30" "1991-12-01:1991-12-31"
#>  [25] "1992-01-01:1992-01-31" "1992-02-01:1992-02-29" "1992-03-01:1992-03-31"
#>  [28] "1992-04-01:1992-04-30" "1992-05-01:1992-05-31" "1992-06-01:1992-06-30"
#>  [31] "1992-07-01:1992-07-31" "1992-08-01:1992-08-31" "1992-09-01:1992-09-30"
#>  [34] "1992-10-01:1992-10-31" "1992-11-01:1992-11-30" "1992-12-01:1992-12-31"
#>  [37] "1993-01-01:1993-01-31" "1993-02-01:1993-02-28" "1993-03-01:1993-03-31"
#>  [40] "1993-04-01:1993-04-30" "1993-05-01:1993-05-31" "1993-06-01:1993-06-30"
#>  [43] "1993-07-01:1993-07-31" "1993-08-01:1993-08-31" "1993-09-01:1993-09-30"
#>  [46] "1993-10-01:1993-10-31" "1993-11-01:1993-11-30" "1993-12-01:1993-12-31"
#>  [49] "1994-01-01:1994-01-31" "1994-02-01:1994-02-28" "1994-03-01:1994-03-31"
#>  [52] "1994-04-01:1994-04-30" "1994-05-01:1994-05-31" "1994-06-01:1994-06-30"
#>  [55] "1994-07-01:1994-07-31" "1994-08-01:1994-08-31" "1994-09-01:1994-09-30"
#>  [58] "1994-10-01:1994-10-31" "1994-11-01:1994-11-30" "1994-12-01:1994-12-31"
#>  [61] "1995-01-01:1995-01-31" "1995-02-01:1995-02-28" "1995-03-01:1995-03-31"
#>  [64] "1995-04-01:1995-04-30" "1995-05-01:1995-05-31" "1995-06-01:1995-06-30"
#>  [67] "1995-07-01:1995-07-31" "1995-08-01:1995-08-31" "1995-09-01:1995-09-30"
#>  [70] "1995-10-01:1995-10-31" "1995-11-01:1995-11-30" "1995-12-01:1995-12-31"
#>  [73] "1996-01-01:1996-01-31" "1996-02-01:1996-02-29" "1996-03-01:1996-03-31"
#>  [76] "1996-04-01:1996-04-30" "1996-05-01:1996-05-31" "1996-06-01:1996-06-30"
#>  [79] "1996-07-01:1996-07-31" "1996-08-01:1996-08-31" "1996-09-01:1996-09-30"
#>  [82] "1996-10-01:1996-10-31" "1996-11-01:1996-11-30" "1996-12-01:1996-12-31"
#>  [85] "1997-01-01:1997-01-31" "1997-02-01:1997-02-28" "1997-03-01:1997-03-31"
#>  [88] "1997-04-01:1997-04-30" "1997-05-01:1997-05-31" "1997-06-01:1997-06-30"
#>  [91] "1997-07-01:1997-07-31" "1997-08-01:1997-08-31" "1997-09-01:1997-09-30"
#>  [94] "1997-10-01:1997-10-31" "1997-11-01:1997-11-30" "1997-12-01:1997-12-31"
#>  [97] "1998-01-01:1998-01-31" "1998-02-01:1998-02-28" "1998-03-01:1998-03-31"
#> [100] "1998-04-01:1998-04-30" "1998-05-01:1998-05-31" "1998-06-01:1998-06-30"
#> [103] "1998-07-01:1998-07-31" "1998-08-01:1998-08-31" "1998-09-01:1998-09-30"
#> [106] "1998-10-01:1998-10-31" "1998-11-01:1998-11-30" "1998-12-01:1998-12-31"
#> [109] "1999-01-01:1999-01-31" "1999-02-01:1999-02-28" "1999-03-01:1999-03-31"
#> [112] "1999-04-01:1999-04-30" "1999-05-01:1999-05-31" "1999-06-01:1999-06-30"
#> [115] "1999-07-01:1999-07-31" "1999-08-01:1999-08-31" "1999-09-01:1999-09-30"
#> [118] "1999-10-01:1999-10-31" "1999-11-01:1999-11-30" "1999-12-01:1999-12-31"
#> [121] "2000-01-01:2000-01-31" "2000-02-01:2000-02-29" "2000-03-01:2000-03-31"
#> [124] "2000-04-01:2000-04-30" "2000-05-01:2000-05-31" "2000-06-01:2000-06-30"
#> [127] "2000-07-01:2000-07-31" "2000-08-01:2000-08-31" "2000-09-01:2000-09-30"
#> [130] "2000-10-01:2000-10-31" "2000-11-01:2000-11-30" "2000-12-01:2000-12-31"
#> [133] "2001-01-01:2001-01-31" "2001-02-01:2001-02-28" "2001-03-01:2001-03-31"
#> [136] "2001-04-01:2001-04-30" "2001-05-01:2001-05-31" "2001-06-01:2001-06-30"
#> [139] "2001-07-01:2001-07-31" "2001-08-01:2001-08-31" "2001-09-01:2001-09-30"
#> [142] "2001-10-01:2001-10-31" "2001-11-01:2001-11-30" "2001-12-01:2001-12-31"
#> [145] "2002-01-01:2002-01-31" "2002-02-01:2002-02-28" "2002-03-01:2002-03-31"
#> [148] "2002-04-01:2002-04-30" "2002-05-01:2002-05-31" "2002-06-01:2002-06-30"
#> [151] "2002-07-01:2002-07-31" "2002-08-01:2002-08-31" "2002-09-01:2002-09-30"
#> [154] "2002-10-01:2002-10-31" "2002-11-01:2002-11-30" "2002-12-01:2002-12-31"
#> [157] "2003-01-01:2003-01-31" "2003-02-01:2003-02-28" "2003-03-01:2003-03-31"
#> [160] "2003-04-01:2003-04-30" "2003-05-01:2003-05-31" "2003-06-01:2003-06-30"
#> [163] "2003-07-01:2003-07-31" "2003-08-01:2003-08-31" "2003-09-01:2003-09-30"
#> [166] "2003-10-01:2003-10-31" "2003-11-01:2003-11-30" "2003-12-01:2003-12-31"
#> [169] "2004-01-01:2004-01-31" "2004-02-01:2004-02-29" "2004-03-01:2004-03-31"
#> [172] "2004-04-01:2004-04-30" "2004-05-01:2004-05-31" "2004-06-01:2004-06-30"
#> [175] "2004-07-01:2004-07-31" "2004-08-01:2004-08-31" "2004-09-01:2004-09-30"
#> [178] "2004-10-01:2004-10-31" "2004-11-01:2004-11-30" "2004-12-01:2004-12-31"
#> [181] "2005-01-01:2005-01-31" "2005-02-01:2005-02-28" "2005-03-01:2005-03-31"
#> [184] "2005-04-01:2005-04-30" "2005-05-01:2005-05-31" "2005-06-01:2005-06-30"
#> [187] "2005-07-01:2005-07-31" "2005-08-01:2005-08-31" "2005-09-01:2005-09-30"
#> [190] "2005-10-01:2005-10-31" "2005-11-01:2005-11-30" "2005-12-01:2005-12-31"
#> [193] "2006-01-01:2006-01-31" "2006-02-01:2006-02-28" "2006-03-01:2006-03-31"
#> [196] "2006-04-01:2006-04-30" "2006-05-01:2006-05-31" "2006-06-01:2006-06-30"
#> [199] "2006-07-01:2006-07-31" "2006-08-01:2006-08-31" "2006-09-01:2006-09-30"
#> [202] "2006-10-01:2006-10-31" "2006-11-01:2006-11-30" "2006-12-01:2006-12-31"
#> [205] "2007-01-01:2007-01-31" "2007-02-01:2007-02-28" "2007-03-01:2007-03-31"
#> [208] "2007-04-01:2007-04-30" "2007-05-01:2007-05-31" "2007-06-01:2007-06-30"
#> [211] "2007-07-01:2007-07-31" "2007-08-01:2007-08-31" "2007-09-01:2007-09-30"
#> [214] "2007-10-01:2007-10-31" "2007-11-01:2007-11-30" "2007-12-01:2007-12-31"
#> [217] "2008-01-01:2008-01-31" "2008-02-01:2008-02-29" "2008-03-01:2008-03-31"
#> [220] "2008-04-01:2008-04-30" "2008-05-01:2008-05-31" "2008-06-01:2008-06-30"
#> [223] "2008-07-01:2008-07-31" "2008-08-01:2008-08-31" "2008-09-01:2008-09-30"
#> [226] "2008-10-01:2008-10-31" "2008-11-01:2008-11-30" "2008-12-01:2008-12-31"
#> [229] "2009-01-01:2009-01-31" "2009-02-01:2009-02-28" "2009-03-01:2009-03-31"
#> [232] "2009-04-01:2009-04-30" "2009-05-01:2009-05-31" "2009-06-01:2009-06-30"
#> [235] "2009-07-01:2009-07-31" "2009-08-01:2009-08-31" "2009-09-01:2009-09-30"
#> [238] "2009-10-01:2009-10-31" "2009-11-01:2009-11-30" "2009-12-01:2009-12-31"
#> [241] "2010-01-01:2010-01-31" "2010-02-01:2010-02-28" "2010-03-01:2010-03-31"
#> [244] "2010-04-01:2010-04-30" "2010-05-01:2010-05-31" "2010-06-01:2010-06-30"
#> [247] "2010-07-01:2010-07-31" "2010-08-01:2010-08-31" "2010-09-01:2010-09-30"
#> [250] "2010-10-01:2010-10-31" "2010-11-01:2010-11-30" "2010-12-01:2010-12-31"
#> [253] "2011-01-01:2011-01-31" "2011-02-01:2011-02-28" "2011-03-01:2011-03-31"
#> [256] "2011-04-01:2011-04-30" "2011-05-01:2011-05-31" "2011-06-01:2011-06-30"
#> [259] "2011-07-01:2011-07-31" "2011-08-01:2011-08-31" "2011-09-01:2011-09-30"
#> [262] "2011-10-01:2011-10-31" "2011-11-01:2011-11-30" "2011-12-01:2011-12-31"
#> [265] "2012-01-01:2012-01-31" "2012-02-01:2012-02-29" "2012-03-01:2012-03-31"
#> [268] "2012-04-01:2012-04-30" "2012-05-01:2012-05-31" "2012-06-01:2012-06-30"
#> [271] "2012-07-01:2012-07-31" "2012-08-01:2012-08-31" "2012-09-01:2012-09-30"
#> [274] "2012-10-01:2012-10-31" "2012-11-01:2012-11-30" "2012-12-01:2012-12-31"
#> [277] "2013-01-01:2013-01-31" "2013-02-01:2013-02-28" "2013-03-01:2013-03-31"
#> [280] "2013-04-01:2013-04-30" "2013-05-01:2013-05-31" "2013-06-01:2013-06-30"
#> [283] "2013-07-01:2013-07-31" "2013-08-01:2013-08-31" "2013-09-01:2013-09-30"
#> [286] "2013-10-01:2013-10-31" "2013-11-01:2013-11-30" "2013-12-01:2013-12-31"
#> [289] "2014-01-01:2014-01-31" "2014-02-01:2014-02-28" "2014-03-01:2014-03-31"
#> [292] "2014-04-01:2014-04-30" "2014-05-01:2014-05-31" "2014-06-01:2014-06-30"
#> [295] "2014-07-01:2014-07-31" "2014-08-01:2014-08-31" "2014-09-01:2014-09-30"
#> [298] "2014-10-01:2014-10-31" "2014-11-01:2014-11-30" "2014-12-01:2014-12-31"
#> [301] "2015-01-01:2015-01-31" "2015-02-01:2015-02-28" "2015-03-01:2015-03-31"
#> [304] "2015-04-01:2015-04-30" "2015-05-01:2015-05-31" "2015-06-01:2015-06-30"
#> [307] "2015-07-01:2015-07-31" "2015-08-01:2015-08-31" "2015-09-01:2015-09-30"
#> [310] "2015-10-01:2015-10-31" "2015-11-01:2015-11-30" "2015-12-01:2015-12-31"
#> [313] "2016-01-01:2016-01-31" "2016-02-01:2016-02-29" "2016-03-01:2016-03-31"
#> [316] "2016-04-01:2016-04-30" "2016-05-01:2016-05-31" "2016-06-01:2016-06-30"
#> [319] "2016-07-01:2016-07-31" "2016-08-01:2016-08-31" "2016-09-01:2016-09-30"
#> [322] "2016-10-01:2016-10-31" "2016-11-01:2016-11-30" "2016-12-01:2016-12-31"
#> [325] "2017-01-01:2017-01-31" "2017-02-01:2017-02-28" "2017-03-01:2017-03-31"
#> [328] "2017-04-01:2017-04-30" "2017-05-01:2017-05-31" "2017-06-01:2017-06-30"
#> [331] "2017-07-01:2017-07-31" "2017-08-01:2017-08-31" "2017-09-01:2017-09-30"
#> [334] "2017-10-01:2017-10-31" "2017-11-01:2017-11-30" "2017-12-01:2017-12-31"
#> [337] "2018-01-01:2018-01-31" "2018-02-01:2018-02-28" "2018-03-01:2018-03-31"
#> [340] "2018-04-01:2018-04-30" "2018-05-01:2018-05-31" "2018-06-01:2018-06-30"
#> [343] "2018-07-01:2018-07-31" "2018-08-01:2018-08-31" "2018-09-01:2018-09-30"
#> [346] "2018-10-01:2018-10-31" "2018-11-01:2018-11-30" "2018-12-01:2018-12-31"
#> [349] "2019-01-01:2019-01-31" "2019-02-01:2019-02-28" "2019-03-01:2019-03-31"
#> [352] "2019-04-01:2019-04-30" "2019-05-01:2019-05-31" "2019-06-01:2019-06-30"
#> [355] "2019-07-01:2019-07-31" "2019-08-01:2019-08-31" "2019-09-01:2019-09-30"
#> [358] "2019-10-01:2019-10-31" "2019-11-01:2019-11-30" "2019-12-01:2019-12-31"
#> [361] "2020-01-01:2020-01-31" "2020-02-01:2020-02-29" "2020-03-01:2020-03-31"
#> [364] "2020-04-01:2020-04-30" "2020-05-01:2020-05-31" "2020-06-01:2020-06-30"
#> [367] "2020-07-01:2020-07-31" "2020-08-01:2020-08-31" "2020-09-01:2020-09-30"
#> [370] "2020-10-01:2020-10-31" "2020-11-01:2020-11-30" "2020-12-01:2020-12-31"
#> [373] "2021-01-01:2021-01-31" "2021-02-01:2021-02-28" "2021-03-01:2021-03-31"
#> [376] "2021-04-01:2021-04-30" "2021-05-01:2021-05-31" "2021-06-01:2021-06-30"
#> [379] "2021-07-01:2021-07-31" "2021-08-01:2021-08-31" "2021-09-01:2021-09-30"
#> [382] "2021-10-01:2021-10-31" "2021-11-01:2021-11-30" "2021-12-01:2021-12-31"

^{Created on 2022-03-19 by the reprex package (v2.0.1)}

Answer 2

I used lubridate for the simplicity of its ymd() function.

require(lubridate)

You start with creating a vector of first days of the month:

start <- seq(ymd("1990-01-01"), ymd("2021-12-01"), by = "month")

Then you create another vector subtracting 1 day to obtain the last day of each month:

b <- start - 1

You remove the first element of that vector

end <- b[-1]

You join them all

paste0(start, ":", end)

There's an easily (manually) fixable issue: the very last interval is incorrect.