Пример данных у меня есть. DF < - data.frame (ID = c (1,2,3,4,5,6), YEAR1 = c (2003,2005,2007,2008,2011, NA), TEST1 = c (0,0, 0,0,0, NA), DROP1 = c (0,0,0,0,0, NA), YEAR2 = c (2005,2007,2009,2010,2013,2011), TEST2 = c (1 ,. ..
вопрос задан: 18 January 2019 18:08