Question

我有一个日期列，其中包含民意测验发生的日期。

这些民意调查偶尔会持续几天（通常但并非总是连续），有时民意调查在一个月内开始，在下个月结束，并且有时将年份输入为YY，有时将年份输入为YYYY。

在有日期范围的地方，通常使用-分隔，但有时使用-时，范围中的日期之间有时会有空格。

我需要使用start_date和end_date列将其清除为一致的日期格式。如果一天进行民意测验，我希望end_date列应为NA或用开始日期填充（如果您有解决方案，那么我可以随时从那里开始做相反的操作，如果需要的话）。在不连续的日期范围内，最早的日期和最新的日期以及中间的停止和重新开始可以被丢弃。

因为格式如此令人讨厌，所以我提供了完整的数据，因为任何解决方案都需要在日期集中的所有日期工作（或处理其中一些日期而不破坏其他日期，所以我们可以解决问题）反复）。

dates <- c("12-15 Feb 2019", "6–11 Feb 2019", "7–10 Feb 2019", "23–30 Jan 2019", 
"24–27 Jan 2019", "9–13 Jan 2019", "13-16 Dec 2018", "13–15 Dec 2018", 
"6–9 Dec 2018", "29 Nov – 2 Dec 2018", "23–25 Nov 2018", "15-18 Nov 2018", 
"15–17 Nov 2018", "8–11 Nov 2018", "1–4 Nov 2018", "25–28 Oct 2018", 
"19–21 Oct 2018", "10–13 Oct 2018", "10–13 Oct 2018", "5–7 Oct 2018", 
"22–24 Sep 2018", "20–23 Sep 2018", "12–15 Sep 2018", "8–10 Sep 2018", 
"6–9 Sep 2018", "25–26 Aug 2018", "24–26 Aug 2018", "24–25 Aug 2018", 
"15-18 Aug 2018", "12-Aug-18", "06-Aug-18", "29-Jul-18", "17-Jul-18", 
"16-Jul-18", "03-Jul-18", "02-Jul-18", "21–24 Jun 2018", "14–17 Jun 2018", 
"14–17 Jun 2018", "02-Jun-18", "31 May – 3 Jun 2018", "24–27 May 2018", 
"17–20 May 2018", "10–13 May 2018", "10–13 May 2018", "10–12 May 2018", 
"3–6 May 2018", "30-Apr-18", "19–22 Apr 2018", "22-Apr-18", "5–8 Apr 2018", 
"5–8 Apr 2018", "3–5 Apr 2018", "24 Mar – 1 Apr 2018", "28-Mar-18", 
"22–25 Mar 2018", "22–25 Mar 2018", "17–25 Mar 2018", "8–11 Mar 2018", 
"3–11 Mar 2018", "1–4 Mar 2018", "22–25 Feb 2018", "24-Feb-18", 
"15–18 Feb 2018", "8–11 Feb 2018", "1–3 Feb 2018", "26–28 Jan 2018", 
"25-Jan-18", "11–15 Jan 2018", "19-Dec-17", "14–17 Dec 2017", 
"12-Dec-17", "7–10 Dec 2017", "05-Dec-17", "30 Nov ? 3 Dec 2017", 
"29-Nov-17", "28-Nov-17", "23–27 Nov 2017", "21-Nov-17", "14-Nov-17", 
"14-Nov-17", "13-Nov-17", "30-Oct-17", "26–29 Oct 2017", "24-Oct-17", 
"12–15 Oct 2017", "04-Oct-17", "01-Oct-17", "26-Sep-17", "21–24 Sep 2017", 
"19-Sep-17", "14–18 Sep 2017", "12-Sep-17", "6–9 Sep 2017", "05-Sep-17", 
"31 Aug – 4 Sep 2017", "28 Aug – 2 Sep 2017", "29-Aug-17", "23-Aug-17", 
"22-Aug-17", "17–21 Aug 2017", "17–20 Aug 2017", "15-Aug-17", 
"08-Aug-17", "3–6 Aug 2017", "01-Aug-17", "25-Jul-17", "20–24 Jul 2017", 
"20–23 Jul 2017", "19-Jul-17", "18-Jul-17", "6–11 Jul 2017", 
"6–9 Jul 2017", "29-Jun-17", "22–27 Jun 2017", "15–18 Jun 2017", 
"14-Jun-17", "26–29 May 2017", "23-May-17", "12–15 May 2017", 
"11-May-17", "10–11 May 2017", "26–30 Apr 2017", "20–23 Apr 2017", 
"13–16 Apr 2017", "6–9 Apr 2017", "1–4 Apr 2017", "30 Mar – 2 Apr 2017", 
"24–27 Mar 2017", "22–25 Mar 2017", "17–20 Mar 2017", "16–19 Mar 2017", 
"10–13 Mar 2017", "3–6 Mar 2017", "23–26 Feb 2017", "16–19 Feb 2017", 
"9–12 Feb 2017", "2–5 Feb 2017", "20–23 Jan 2017", "13–16 Jan 2017", 
"12-Jan-17", "9–12 Dec 2016", "1–4 Dec 2016", "25–28 Nov 2016", 
"24–26 Nov 2016", "17–20 Nov 2016", "11–14 Nov 2016", "3–6 Nov 2016", 
"20–23 Oct 2016", "14–17 Oct 2016", "7–10 Oct 2016", "6–9 Oct 2016", 
"22–25 Sep 2016", "9–12 Sep 2016", "8–11 Sep 2016", "26–29 Aug 2016", 
"25–28 Aug 2016", "19–22 Aug 2016", "12–15 Aug 2016", "5–8 Aug 2016", 
"27 Jul – 1 Aug 2016", "20–24 Jul 2016", "13–17 Jul 2016", "6–10 Jul 2016", 
"30 Jun – 3 Jul 2016", "28 Jun – 1 Jul 2016", "30-Jun-16", "27–30 Jun 2016", 
"28–29 Jun 2016", "26–29 Jun 2016", "28 Jun – 1 Jul 2016", "30-Jun-16", 
"27–30 Jun 2016", "28–29 Jun 2016", "26–29 Jun 2016", "23–26 Jun 2016", 
"23–26 Jun 2016", "23-Jun-16", "20–22 Jun 2016", "16–19 Jun 2016", 
"16–19 Jun 2016", "16-Jun-16", "14–16 Jun 2016", "9–12 Jun 2016", 
"09-Jun-16", "2–5 Jun 2016", "2–5 Jun 2016", "02-Jun-16", "31 May – 2 Jun 2016", 
"26–29 May 2016", "21–22,\n                      28–29 May 2016", 
"26-May-16", "19–22 May 2016", "19–22 May 2016", "19-May-16", 
"17–19 May 2016", "14–15 May 2016", "12–15 May 2016", "6–8 May 2016", 
"5–8 May 2016", "5–8 May 2016", "5–7 May 2016", "4–6 May 2016", 
"05-May-16", "27 Apr – 1 May 2016", "23–24, 30 Apr – 1 May 2016", 
"20–24 Apr 2016", "14–17 Apr 2016", "13–17 Apr 2016", "9–10,\n                      16–17 Apr 2016", 
"14–16 Apr 2016", "14-Apr-16", "6–10 Apr 2016", "31 Mar – 3 Apr 2016", 
"26–27 Mar, 2–3 Apr 2016", "21-Mar-16", "17–20 Mar 2016", "16–20 Mar 2016", 
"12–13,\n                      19–20 Mar 2016", "10–12 Mar 2016", 
"3–6 Mar 2016", "2–6 Mar 2016", "27–28 Feb, 5–6 Mar 2016", "24–28 Feb 2016", 
"18–21 Feb 2016", "17–21 Feb 2016", "13–14, 20–21 Feb 2016", 
"11–13 Feb 2016", "11-Feb-16", "3–7 Feb 2016", "30–31 Jan,\n                      6–7 Feb 2016", 
"28–31 Jan 2016", "16–17, 23–24 Jan 2016", "21-Jan-16", "15–18 Jan 2016", 
"2–3, 9–10 Jan 2016", "15-Dec-15", "5–6, 12–13 Dec 2015", "08-Dec-15", 
"4–6 Dec 2015", "01-Dec-15", "21–22, 28–29 Nov 2015", "26-Nov-15", 
"24-Nov-15", "19–22 Nov 2015", "7–8, 14–15 Nov 2015", "12–14 Nov 2015", 
"10-Nov-15", "6–8 Nov 2015", "03-Nov-15", "24–25 Oct,\n                      1 Nov 2015", 
"27-Oct-15", "23–25 Oct 2015", "22-Oct-15", "20-Oct-15", "10–11, 17–18 Oct 2015", 
"15–17 Oct 2015", "13-Oct-15", "9–11 Oct 2015", "26–27 Sep, 1–5 Oct 2015", 
"1–4 Oct 2015", "24–28 Sep 2015", "17–21 Sep 2015", "19–20 Sep 2015", 
"17–20 Sep 2015", "15–16 Sep 2015", "15-Sep-15", "12–13 Sep 2015", 
"5–6 Sep 2015", "4–6 Sep 2015", "26–30 Aug 2015", "27-Aug-15", 
"22–23 Aug 2015", "20–23 Aug 2015", "13–15 Aug 2015", "11–14 Aug 2015", 
"8–9 Aug 2015", "8–9 Aug 2015", "4–7 Aug 2015", "06-Aug-15", 
"28–31 Jul 2015", "30-Jul-15", "25–26 Jul 2015", "16–19 Jul 2015", 
"14–17 Jul 2015", "11–12 Jul 2015", "4–5 Jul 2015", "2–4 Jul 2015", 
"27–28 Jun 2015", "16-Jun-15", "16-Jun-15", "13–14 Jun 2015", 
"11–13 Jun 2015", "11–13 Jun 2015", "02-Jun-15", "02-Jun-15", 
"23–24, 30–31 May 2015", "26-May-15", "18-May-15", "17-May-15", 
"17-May-15", "13-May-15", "7–10 May 2015", "04-May-15", "04-May-15", 
"28-Apr-15", "21-Apr-15", "11–12,\n                      18–19 Apr 2015", 
"14-Apr-15", "10–12 Apr 2015", "9–11 Apr 2015", "28–29 Mar, 3–6 Apr 2015", 
"29-Mar-15", "20–22 Mar 2015", "14–15, 21–22 Mar 2015", "17-Mar-15", 
"10-Mar-15", "7–8 Mar 2015", "28 Feb–1, 7–8 Mar 2015", "26–28 Feb 2015", 
"20–22 Feb 2015", "20–22 Feb 2015", "6–8 Feb 2015", "31 Jan–1, 7–8 Feb 2015", 
"05-Feb-15", "4–5 Feb 2015", "28–30 Jan 2015", "27-Jan-15", "r27 Jan 2015", 
"20-Jan-15", "13-Jan-15", "12-Jan-15", "23–27 Dec 2014", "16-Dec-14", 
"12–15 Dec 2014", "6–7, 13–14 Dec 2014", "4–6 Dec 2014", "2–4 Dec 2014", 
"02-Dec-14", "29–30 Nov 2014", "22–23, 29–30 Nov 2014", "25-Nov-14", 
"21-Nov-14", "18-Nov-14", "17-Nov-14", "17-Nov-14", "11-Nov-14", 
"04-Nov-14", "04-Nov-14", "25–26 Oct,\n                      1–2 Nov 2014", 
"30 Oct–1 Nov 2014", "28-Oct-14", "23-Oct-14", "21-Oct-14", "21-Oct-14", 
"20-Oct-14", "14-Oct-14", "07-Oct-14", "4–5 Oct 2014", "4–5 Oct 2014", 
"23-Sep-14", "13–14,\n                      20–21 Sep 2014", 
"18-Sep-14", "30–31 Aug, 6–7 Sep 2014", "5–7 Sep 2014", "22–24 Aug 2014", 
"16–17, 23–24 Aug 2014", "19-Aug-14", "9–10 Aug 2014", "8–10 Aug 2014", 
"25–27 Jul 2014", "11–13 Jul 2014", "01-Jul-14", "30-Jun-14", 
"27–29 Jun 2014", "13–15 Jun 2014", "30 May–1 Jun 2014", "27-May-14", 
"20-May-14", "17–18 May 2014", "16–18 May 2014", "15–17 May 2014", 
"04-May-14", "2–4 May 2014", "30-Apr-14", "22-Apr-14", "15-Apr-14", 
"13-Apr-14", "08-Apr-14", "07-Apr-14", "4–6 Apr 2014", "25-Mar-14", 
"25-Mar-14", "21–23 Mar 2014", "18-Mar-14", "13–15 Mar 2014", 
"7–9 Mar 2014", "05-Mar-14", "23-Feb-14", "21–23 Feb 2014", "15-Feb-14", 
"7–9 Feb 2014", "28-Jan-14", "23-Jan-14", "17–20 Jan 2014", "13-Jan-14", 
"16-Dec-13", "15-Dec-13", "6–8 Dec 2013", "28 Nov–2 Dec 2013", 
"30 Nov–1 Dec 2013", "22–24 Nov 2013", "21–23 Nov 2013", "8–10 Nov 2013", 
"25–27 Oct 2013", "19–20 Oct 2013", "21–22 Sep 2013", "19–22 Sep 2013", 
"12–15 Sep 2013", "4–6 Sep 2013", "05-Sep-13", "3–5 Sep 2013", 
"4–6 Sep 2013", "05-Sep-13", "4–5 Sep 2013", "3–5 Sep 2013", 
"04-Sep-13", "2–4 Sep 2013", "1–4 Sep 2013", "03-Sep-13", "30 Aug–1 Sep 2013", 
"30 Aug–1 Sep 2013", "29 Aug–1 Sep 2013", "28–29 Aug 2013", "28–29 Aug 2013", 
"26-Aug-13", "21–25 Aug 2013", "23–25 Aug 2013", "23–25 Aug 2013", 
"18–22 Aug 2013", "16–18 Aug 2013", "16–18 Aug 2013", "16–18 Aug 2013", 
"14–18 Aug 2013", "14–15 Aug 2013", "12–13 Aug 2013", "9–12 Aug 2013", 
"9–11 Aug 2013", "9–11 Aug 2013", "10-Aug-13", "7–9 Aug 2013", 
"6–8 Aug 2013", "04-Aug-13", "2–4 Aug 2013", "2–4 Aug 2013", 
"1–4 Aug 2013", "26–28 Jul 2013", "25–28 Jul 2013", "23–25 Jul 2013", 
"18–22 Jul 2013", "19–21 Jul 2013", "19–21 Jul 2013", "18-Jul-13", 
"12–14 Jul 2013", "11–14 Jul 2013", "11–13 Jul 2013", "5–8 Jul 2013", 
"5–7 Jul 2013", "5–7 Jul 2013", "4–7 Jul 2013", "28–30 Jun 2013", 
"28–30 Jun 2013", "27–30 Jun 2013", "27–28 Jun 2013", "27-Jun-13", 
"21–23 Jun 2013", "21–23 Jun 2013", "20–23 Jun 2013", "14–16 Jun 2013", 
"13–16 Jun 2013", "13–15 Jun 2013", "11–13 Jun 2013", "7–10 Jun 2013", 
"6–10 Jun 2013", "31 May–2 Jun 2013", "31 May–2 Jun 2013", "30 May–2 Jun 2013", 
"24–26 May 2013", "23–26 May 2013", "17–19 May 2013", "17–19 May 2013", 
"16–19 May 2013", "16–18 May 2013", "15–16 May 2013", "10–12 May 2013", 
"9–12 May 2013", "3–5 May 2013", "3–5 May 2013", "2–5 May 2013", 
"02-May-13", "26–28 Apr 2013", "25–28 Apr 2013", "18–22 Apr 2013", 
"18–22 Apr 2013", "19–21 Apr 2013", "11–14 Apr 2013", "11–14 Apr 2013", 
"11–13 Apr 2013", "9–11 Apr 2013", "02-May-13", "5–7 Apr 2013", 
"4–7 Apr 2013", "4–7 Apr 2013", "29 Mar–1 Apr 2013", "28 Mar–1 Apr 2013", 
"22–24 Mar 2013", "21–24 Mar 2013", "22–23 Mar 2013", "21–24 Mar 2013", 
"22–25 Mar 2013", "14–17 Mar 2013", "14–17 Mar 2013", "14–16 Mar 2013", 
"7–10 Mar 2013", "7–10 Mar 2013", "8–10 Mar 2013", "5–7 Mar 2013", 
"28 Feb–3 Mar 2013", "28 Feb–3 Mar 2013", "21–24 Feb 2013", "16–17/23–24 Feb 2013", 
"22–24 Feb 2013", "14–17 Feb 2013", "14–16 Feb 2013", "7–10 Feb 2013", 
"9–10 Feb 2013", "1–4 Feb 2013", "2–3 Feb 2013", "1–3 Feb 2013", 
"1–3 Feb 2013", "23–28 Jan 2013", "19–20/26–27 Jan 2013", "16–20 Jan 2013", 
"9–13 Jan 2013", "11–13 Jan 2013", "5–6/12–13 Jan 2013", "12–16 Dec 2012", 
"8–9/15–16 Dec 2012", "13–15 Dec 2012", "5–9 Dec 2012", "7–9 Dec 2012", 
"28 Nov–2 Dec 2012", "24–25 Nov/1–2 Dec 2012", "29–30 Nov 2012", 
"27–29 Nov 2012", "23–25 Nov 2012", "21–25 Nov 2012", "14–18 Nov 2012", 
"10–11/17–18 Nov 2012", "15–17 Nov 2012", "9–11 Nov 2012", "7–11 Nov 2012", 
"2–6 Nov 2012", "2–4 Nov 2012", "27–28 Oct/3–4 Nov 2012", "26–28 Oct 2012", 
"25–28 Oct 2012", "13–14/20–21 Oct 2012", "17–21 Oct 2012", "18–20 Oct 2012", 
"10–14 Oct 2012", "5–7 Oct 2012", "3–7 Oct 2012", "29–30 Sep/6–7 Oct 2012", 
"26–30 Sep 2012", "22–23 Sep 2012", "19–23 Sep 2012", "17–20 Sep 2012", 
"14–16 Sep 2012", "12–16 Sep 2012", "8–9/15–16 Sep 2012", "13–15 Sep 2012", 
"29 Aug–2 Sep 2012", "31 Aug–2 Sep 2012", "1–2 Sep 2012", "22–26 Aug 2012", 
"23–25 Aug 2012", "15–19 Aug 2012", "17–19 Aug 2012", "11–12/18–19 Aug 2012", 
"8–12 Aug 2012", "3–5 Aug 2012", "1–5 Aug 2012", "28–29 Jul/4–5 Aug 2012", 
"25–29 Jul 2012", "26–28 Jul 2012", "20–22 Jul 2012", "18–22 Jul 2012", 
"14–15/21–22 Jul 2012", "11–15 Jul 2012", "6–8 Jul 2012", "4–8 Jul 2012", 
"30 Jun–1/7–8 Jul 2012", "27 Jun–1 Jul 2012", "22–24 Jun 2012", 
"20–24 Jun 2012", "16–17/23–24 Jun 2012", "13–17 Jun 2012", "15–17 Jun 2012", 
"6–11 Jun 2012", "9–10 Jun 2012", "7–10 Jun 2012", "2–3 Jun 2012", 
"31 May–2 Jun 2012", "30 May–3 Jun 2012", "26–27 May 2012", "23–27 May 2012", 
"25–27 May 2012", "16–20 May 2012", "19–20 May 2012", "12–13 May 2012", 
"11–13 May 2012", "9–13 May 2012", "9–10 May 2012", "9–10 May 2012", 
"5–6 May 2012", "2–6 May 2012", "27–29 Apr 2012", "27–29 Apr 2012", 
"25–29 Apr 2012", "21–22 Apr 2012", "18–22 Apr 2012", "17–19 Apr 2012", 
"13–15 Apr 2012", "11–15 Apr 2012", "7–8/14–15 Apr 2012", "4–9 Apr 2012", 
"31 Mar–1 Apr 2012", "28 Mar–1 Apr 2012", "29–31 Mar 2012", "21–25 Mar 2012", 
"24–25 Mar 2012", "23–25 Mar 2012", "14–18 Mar 2012", "10–11/17–18 Mar 2012", 
"9–11 Mar 2012", "7–11 Mar 2012", "3–4 Mar 2012", "29 Feb–4 Mar 2012", 
"25–26 Feb 2012", "23–26 Feb 2012", "22–26 Feb 2012", "23–24 Feb 2012", 
"22–23 Feb 2012", "15–19 Feb 2012", "11–12/18–19 Feb 2012", "10–12 Feb 2012", 
"8–10 Feb 2012", "7–8 Feb 2012", "4–5 Feb 2012", "1–5 Feb 2012", 
"2–4 Feb 2012", "28–29 Jan 2012", "27–29 Jan 2012", "25–29 Jan 2012", 
"27–28 Jan 2012", "18–22 Jan 2012", "14–15/21–22 Jan 2012", "17–18 Jan 2012", 
"11–15 Jan 2012", "7–8 Jan 2012", "14–18 Dec 2011", "10–11/17–18 Dec 2011", 
"7–11 Dec 2011", "8–10 Dec 2011", "2–4 Dec 2011", "30 Nov–4 Dec 2011", 
"26–27 Nov/3–4 Dec 2011", "23–27 Nov 2011", "19–20 Nov 2011", 
"18–20 Nov 2011", "16–20 Nov 2011", "9–13 Nov 2011", "5–6/12–13 Nov 2011", 
"10–12 Nov 2011", "3–6 Nov 2011", "2–6 Nov 2011", "2–3 Nov 2011", 
"26–30 Oct 2011", "29–30 Oct 2011", "25–26 Oct 2011", "22–23 Oct 2011", 
"21–23 Oct 2011", "19–23 Oct 2011", "15–16Oct 2011", "14–16 Oct 2011", 
"12–16 Oct 2011", "13–15 Oct 2011", "8–9 Oct 2011", "7–9 Oct 2011", 
"4–9 Oct 2011", "27 Sep–2 Oct 2011", "24–25 Sep/1–2 Oct 2011", 
"20–25 Sep 2011", "16–18 Sep 2011", "13–18 Sep 2011", "10–11/17–18 Sep 2011", 
"7–11 Sep 2011", "8–10 Sep 2011", "2–4 Sep 2011", "31 Aug–4 Sep 2011", 
"27–28 Aug/3–4 Sep 2011", "24–28 Aug 2011", "19–21 Aug 2011", 
"17–21 Aug 2011", "13–14/20–21 Aug 2011", "10–14 Aug 2011", "11–13 Aug 2011", 
"9–10 Aug 2011", "5–7 Aug 2011", "3–7 Aug 2011", "30–31 Jul/6–7 Aug 2011", 
"c. 3 Aug 2011", "27–31 Jul 2011", "22–24 Jul 2011", "20–24 Jul 2011", 
"16–17/23–24 Jul 2011", "13–17 Jul 2011", "14–16 Jul 2011", "13–14 Jul 2011", 
"9–10 Jul 2011", "8–10 Jul 2011", "6–10 Jul 2011", "29 Jun–3 Jul 2011", 
"25–26 Jun/1–2 Jul 2011", "24–26 Jun 2011", "22–26 Jun 2011", 
"11–12/18–19 Jun 2011", "15–19 Jun 2011", "14–16 Jun 2011", "8–13 Jun 2011", 
"10–12 Jun 2011", "4–5 Jun 2011", "1–5 Jun 2011", "31 May–2 Jun 2011", 
"25–29 May 2011", "27–29 May 2011", "21–22/28–29 May 2011", "18–22 May 2011", 
"14–15 May 2011", "13–15 May 2011", "11–15 May 2011", "12–14 May 2011", 
"7–8 May 2011", "4–8 May 2011", "3–4 May 2011", "29 Apr–1 May 2011", 
"28 Apr–1 May 2011", "23–24/30 Apr–1 May 2011", "20–26 Apr 2011", 
"13–17 Apr 2011", "9–10/16–17 Apr 2011", "14–16 Apr 2011", "6–10 Apr 2011", 
"2–3 Apr 2011", "1–3 Apr 2011", "30 Mar–3 Apr 2011", "26–27 Mar 2011", 
"23–27 Mar 2011", "22–24 Mar 2011", "19–20 Mar 2011", "18–20 Mar 2011", 
"16–20 Mar 2011", "16–17 Mar 2011", "12–13 Mar 2011", "9–13 Mar 2011", 
"10–12 Mar 2011", "8–10 Mar 2011", "5–6 Mar 2011", "4–6 Mar 2011", 
"2–6 Mar 2011", "26–27 Feb 2011", "22–27 Feb 2011", "21–23 Feb 2011", 
"18–20 Feb 2011", "15–20 Feb 2011", "12–13/19–20 Feb 2011", "8–13 Feb 2011", 
"10–12 Feb 2011", "4–6 Feb 2011", "1–6 Feb 2011", "29–30 Jan/5–6 Feb 2011", 
"1–3 Feb 2011", "25–30 Jan 2011", "18–23 Jan 2011", "15–16/22–23 Jan 2011", 
"11–16 Jan 2011", "8–9 Jan 2011", "14–19 Dec 2010", "11–12 Dec 2010", 
"8–12 Dec 2010", "7–12 Dec 2010", "4–5 Dec 2010", "3–5 Dec 2010", 
"30 Nov–5 Dec 2010", "23–28 Nov 2010", "20–21/27–28 Nov 2010", 
"19–21 Nov 2010", "16–21 Nov 2010", "18–20 Nov 2010", "9–14 Nov 2010", 
"6–7/13–14 Nov 2010", "5–7 Nov 2010", "2–7 Nov 2010", "26–31 Oct 2010", 
"23–24/30–31 Oct 2010", "22–24 Oct 2010", "19–24 Oct 2010", "21–23 Oct 2010", 
"12–17 Oct 2010", "9–10/16–17 Oct 2010", "8–10 Oct 2010", "5–10 Oct 2010", 
"2–3 Oct 2010", "30 Sep–1 Oct 2010", "21–26 Sep 2010", "18–19 Sep 2010", 
"14–19 Sep 2010", "15–16 Sep 2010", "10–12 Sep 2010", "7–12 Sep 2010", 
"31 Aug–5 Sep 2010", "28–29 Aug/4–5 Sep 2010", "24–29 Aug 2010", 
"25–26 Aug 2010", "c. 21 Aug 2010", "17–19 Aug 2010", "13–19 Aug 2010"
)

要在数据集中查找的某些特别奇异的日期 "30 Nov ? 3 Dec 2017"
"21–22,\n 28–29 May 2016" "24–25 Oct,\n 1 Nov 2015" "29–30 Sep/6–7 Oct 2012"

Answer 1

这是一个有趣的问题！但是我认为可以使用正则表达式解决。

如何？

library(tidyverse)
tibble(dates = dates) %>%
  mutate(end_year = str_extract(dates, "[0-9]*$"),
         end_year = ifelse(str_length(end_year) == 2, paste0("20", end_year), end_year),
         month_one = str_extract(dates, "[A-Z][a-z][a-z]"),
         month_two = str_sub(str_extract(dates, "[A-Z][a-z][a-z].*[A-Z][a-z][a-z]"), start = -3),
         month_two = if_else(is.na(month_two), month_one, month_two),
         day_one = str_extract(dates, "[0-9]+"),
         dates_without_day_one = gsub("^[0-9]+", "", dates),
         day_two = str_extract(dates_without_day_one, "[0-9]+"),
         day_two = str_squish(gsub("[-–]", "", day_two)),
         day_three_four = str_extract(dates, "/.+[-–] *[0-9]+"),
         day_three = str_extract(day_three_four, "/ *[0-9]+"),
         day_three = str_squish(gsub("/", "", day_three)),
         day_four = str_extract(day_three_four, "[-–] *[0-9]+"),
         day_four = str_squish(gsub("[-–]", "", day_four))
  ) %>%
  # dates that are only a single day:
  mutate(day_two = if_else(is.na(day_two), day_one, day_two)) %>%
  # dates that actually have four days:
  mutate(day_one = ifelse(is.na(day_three),
                           day_one,
                           round((as.numeric(day_one) + as.numeric(day_two)) / 2)),
         day_two = ifelse(is.na(day_three),
                           day_two,
                           round((as.numeric(day_three) + as.numeric(day_four)) / 2))) %>%
  select(-day_three_four, -dates_without_day_one) %>%

  mutate(start_date = as.Date(paste(end_year,month_one, day_one, sep = "-"), format = "%Y-%b-%d"),
         end_date = as.Date(paste(end_year,month_two, day_two, sep = "-"), format = "%Y-%b-%d")) %>%
  select(dates, start_date, end_date, everything())

交付：

# A tibble: 838 x 10
   dates               start_date end_date   end_year month_one month_two day_one day_two day_three day_four
   <chr>               <date>     <date>     <chr>    <chr>     <chr>     <chr>   <chr>   <chr>     <chr>   
 1 12-15 Feb 2019      2019-02-12 2019-02-15 2019     Feb       Feb       12      15      NA        NA      
 2 6–11 Feb 2019       2019-02-06 2019-02-11 2019     Feb       Feb       6       11      NA        NA      
 3 7–10 Feb 2019       2019-02-07 2019-02-10 2019     Feb       Feb       7       10      NA        NA      
 4 23–30 Jan 2019      2019-01-23 2019-01-30 2019     Jan       Jan       23      30      NA        NA      
 5 24–27 Jan 2019      2019-01-24 2019-01-27 2019     Jan       Jan       24      27      NA        NA      
 6 9–13 Jan 2019       2019-01-09 2019-01-13 2019     Jan       Jan       9       13      NA        NA      
 7 13-16 Dec 2018      2018-12-13 2018-12-16 2018     Dec       Dec       13      16      NA        NA      
 8 13–15 Dec 2018      2018-12-13 2018-12-15 2018     Dec       Dec       13      15      NA        NA      
 9 6–9 Dec 2018        2018-12-06 2018-12-09 2018     Dec       Dec       6       9       NA        NA      
10 29 Nov – 2 Dec 2018 2018-11-29 2018-12-02 2018     Nov       Dec       29      2       NA        NA

Answer 2

我不得不面对来自世界各地的文档的相同问题。最佳答案是在创建输入公式时强制日期格式为上游。

此答案不能解决您的确切日期范围问题，但是您可以调整我在这里推荐的解决方案。我使用了正则表达式模式。我在这里粘贴在python中类似解决方案中使用过的模式。

# 2019/02/20 or 2019-02-20
(?:|[\s\/\.:])+(\d{4})[\/\-\.\s](\d{2})[\/\-\.\s](\d{2})(?:$|[\s\/\.\-])+
# 02/20/2019 or 20/02/2019
(?:|[\/\s\.:])+(\d{2})[\/\-\.\s](\d{2})[\/\-\.\s](\d{4})(?:$|[\/\s\.\-])+
# 20 Feb 2019 or 20-Feb-2019
(?:^|[\s\.:])+(\d{2})[\/\-\.\s]?([a-zA-Z]{2,3})[\/\-\.\s]?(\d{4})(?:$|[\s\.\-])+
# 2019 Feb 20
(?:^|[\s\.:])+(\d{4})[\/\-\.\s]?([a-zA-Z]{2,3})[\/\-\.\s]?(\d{2})(?:$|[\s\.\-])+
# February 20th, 2019
(?:^|[\s\.:])+([a-zA-Z]{3,15})\s(\d{1,2})\s?[a-zA-Z]{2},\s?(\d{2,4})(?:$|[\s\.\-])+
# Feb 20 2019 or February 20 2019
(?:^|[\s\.:])*([a-zA-Z]{3,15})[ _\-\/\\\.]?(\d{1,2})[ _\-\/\\\.](\d{2,4})(?:$|[\s\.\-])+
#20-FEB-2019
(?:^|[\s\.\-:])+(\d{1,2})[ _\-\/\\\.]([a-zA-Z]{3,15})[ _\-\/\\\.](\d{2,4})(?:$|[\s\.\-])+
#2019.Feb.20
(?:^|[\s\.\-:])+(\d{4})[ _\-\/\\\.]([a-zA-Z]{3,15})[ _\-\/\\\.](\d{1,2})(?:$|[\s\.\-])+
# 20 Feb. 2019
(?:^|[\s\.\-:])+(\d{2})[\/\-\.\s]([a-zA-Z]{3,15})[\/\-\.\s]{1,2}(\d{4})(?:$|[\s\.\-])+

这些正则表达式模式包含三组，您可以提取并手动测试以防解析歧义日期（例如：02/01/2019）。

在实施解决方案之前，我建议您按以下步骤进行操作：

列出所有要解析的日期，每行一个
将它们全部粘贴到正则表达式测试器中（例如：online regex tester）
尝试（并最终修改）以下每个模式
验证您是否正确捕获了第1到第3组
检查正确捕获的日期，直到列表中没有任何人为止，并且不会发生冲突
在R中实现日期解析功能
暗中希望日期会有国际标准

解析复杂的日期列

2 个答案: