Today we will learn how to work with dates and time. It’s an essential skill because in almost every Python program you work with time one way or another. It can be really confusing at first how to work with them because we have dates, time, timezones, timedeltas.<\/p>\n
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Module For example, let’s start with class Python<\/em><\/span><\/p>\n It prints the day in such format: Python<\/em><\/span><\/p>\n Pretty obvious and easy, right? Python<\/em><\/span><\/p>\n The output isn’t really pretty. What if we want to have a pretty output with the date and time alltogether but only using Python<\/em><\/span><\/p>\n Sounds reasonable, right? Python<\/em><\/span><\/p>\n Check it out for yourself. The last thing I want to mention before we go any further. There is a method called Let’s start off with some basic examples. First, we want to store a data about the date and print it out. By the time you are reading this, you should already know how to do it. If you don’t know, don’t worry. We will simply create a variable that will store a data about the date we want.<\/p>\n Python<\/em><\/span><\/p>\n Now, if we want to print out a current day, month and year seperately, we can simply do the following:<\/p>\n Python<\/em><\/span><\/p>\n Another interesting thing is we can actually know which day of the week it is by using methods Python<\/em><\/span><\/p>\n The only difference between those 2 methods is if today is Monday (this is my case, becase I am writing this on Monday), Python<\/em><\/span><\/p>\n Well, you might be wondering why this is important. Good thinking, let’s find out how many days are left before my birthday, for example:<\/p>\n Python<\/em><\/span><\/p>\n We have basically covered most of the Python<\/em><\/span><\/p>\n Let’s find out how to print the current date and time including UTC using methods Python<\/em><\/span><\/p>\n If you follow along, you may find that both outputs are the same. So it doesn’t really matter which one to use. It’s all up to you. Now let’s go and see what happens if we put specific timezone.<\/p>\n Python<\/em><\/span><\/p>\n As you can see by its output, we see the difference between Python<\/em><\/span><\/p>\n So you can choose any you want from that list. For example, we want to have a pretty formated date with an American version where Python<\/em><\/span><\/p>\n Now, you don’t have to memorize this. If you ever feel like printing something in specific format, just go to official site and see all attributes or go to a different chapter in this article where I put all attributes, so you won’t have to google so much. Python<\/em><\/span><\/p>\n Let’s think about some programs that may require working with Wikipedia.py<\/em><\/span><\/p>\n Well, that went well, didn’t it? Let us think about some other examples. For example, we have to work with big data or we just need to generate random data to work with it. How can we do that? Let’s say, I want to generate data for year, month, day and birthday. It doesn’t need to be specific, we just need a lot of this data.<\/p>\n random.py<\/em><\/span><\/p>\n That’s it! We can print this data and generate loop, so it iterates thus generates random data as much as we want! timer.py<\/em><\/span><\/p>\n There are many cool things you can do with Python<\/em><\/span><\/p>\n Well, this one was easy. What if we want to have a current date in day name and month name? Sounds like something similar? Well, it is!<\/p>\n Python<\/em><\/span><\/p>\n Now, let’s think we want to have a program that works and runs just fine but with some pause in between? What should we do? Well, that is quite easy actually, all thanks to Python<\/em><\/span><\/p>\n Basically we are getting the program that prints 10 times with an interval of 5 seconds the string We have learnt how to do simple things with datetime<\/code> is based on 3 classes:<\/p>\n\n
date<\/code><\/li>\ntime<\/code><\/li>\ndatetime<\/code><\/li>\n<\/ul>\ndate<\/code>. It receieves 3 parameters: year, month and day. Let’s try to find out what day is today:<\/p>\nfrom datetime import date\r\ntoday = date.today()\r\nprint(today)<\/pre>\n
year<\/code> – month<\/code> – day<\/code>. For instance, we want to print it like this: day<\/code>.month<\/code>.year<\/code>. What should we do? We can use format()<\/code> method.<\/p>\nfrom datetime import date\r\ntoday = date.today()\r\nprint(\"{}.{}.{}\".format(today.day, today.month, today.year))<\/pre>\n
\nLet’s take a quick look at class time<\/code>. It receives parameters like hour, minute, second, microsecond. All these are not mandatory, so if we skip some, they will be initialized as zero.<\/p>\nfrom datetime import datetime\r\ndatetime.now().time()<\/pre>\n
time<\/code> module? Is it possible? For Python almost<\/span> everything is possible.<\/p>\nimport time\r\ntime.ctime()<\/pre>\n
\nThe last one is class datetime<\/code>. It expands previous examples by working together with time and date. It receives all parameters from previous two, but the first 3 are a must to complete. Let’s create the variable now<\/code> that stores information about date and time. Then we will print only date and only time using format()<\/code> method.<\/p>\nfrom datetime import datetime\r\nnow = datetime.now()\r\nprint(now)\r\nprint(\"{}.{}.{} {}:{}\".format(now.day, now.month, now.year, now.hour, now.minute))\r\nprint(now.date())\r\nprint(now.time())<\/pre>\nstrptime()<\/code> which is used to convert string to datetime variable. There are couply things that may look like Regular Expressions you should know:<\/p>\n\n
%d<\/code> day of the month;<\/li>\n%m<\/code> number of the month;<\/li>\n%y<\/code> year with 2 digits;<\/li>\n%Y<\/code> year with 4 digits;<\/li>\n%H<\/code> hour in 24 format;<\/li>\n%M<\/code> minute;<\/li>\n%S<\/code> second;<\/li>\n<\/ul>\n<\/a>2. Examples<\/h2>\n
<\/a>2.1 Basic examples<\/h3>\n
import datetime\r\nday = datetime.date(2017,7,12) # be careful to NOT put 07. It will give you a syntax error\r\nprint(day) #2017-07-12<\/pre>\n
import datetime\r\nday = datetime.date.today() \r\nprint(day.year) #outputs the current year\r\nprint(day.month) #outputs the current month\r\nprint(day.day) #outputs the current day<\/pre>\n
weekday()<\/code> and isoweekday()<\/code>. Let’s try it out:<\/p>\nimport datetime\r\nday = datetime.date.today() \r\nprint(day.weekday()) #outputs 0\r\nprint(day.isoweekday()) #outputs 1<\/pre>\n
weekday()<\/code>> returns 0<\/code> for Monday and 6<\/code> for Sunday. The isoweekday()<\/code> returns 1<\/code> for Monday and 7<\/code> for Sunday. It doesn’t make much difference as you can see.
\nThere is another cool feature called timedelta<\/code>. It is basically the difference between 2 days. For example, we want to know what day will be in 15 days from today. What should we do?<\/p>\nimport datetime\r\nnow = datetime.date.today()\r\ndelta = datetime.timedelta(days=15)\r\nprint(now + delta)<\/pre>\n
import datetime\r\nnow = datetime.date.today()\r\nmy_birthday = datetime.date(2017, 9 ,20) #we put 2017 as a year because we want to find out how many days are left within this year\r\ndays_left = my_birthday - now\r\nprint(days_left.days)<\/pre>\n
datime<\/code> module. However, there is one thing left. We didn’t really work with Timezones, right? I recommend you to go along with me right now and go install pytz<\/code> package from pip<\/code> by simply typing pip install pytz<\/code> in your terminal. Then we are ready to start:<\/p>\nimport datetime\r\nimport pytz\r\ndate_timezone = datetime.datetime(2017, 7, 12, 10, 30, 45, tzinfo=pytz.UTC)\r\nprint(date_timezone)\r\n<\/pre>\n
now()<\/code> and utcnow()<\/code>.<\/p>\nimport datetime\r\nimport pytz\r\nnow_timezone = datetime.datetime.now(tz=pytz.UTC)\r\nprint(now_timezone)\r\nutcnow_timezone = datetime.datetime.utcnow().replace(tzinfo=pytz.UTC)\r\nprint(utcnow_timezone)\r\n<\/pre>\n
import datetime\r\nimport pytz\r\nutcnow_data = datetime.datetime.now(tz=pytz.UTC)\r\nprint(utcnow_data)\r\nmy_data = utcnow_data.astimezone(pytz.timezone(\"US\/Eastern\"))\r\nprint(my_data)\r\n<\/pre>\n
utcnow_data<\/code> and my_data<\/code>. So you are probably wondering, ‘How do I know which timezone to put there?’. That’s a very good question. Except Google, we can surely type in all timezones so that we won’t have to read official documentation to pytz<\/code>. Note: I encourage you to read the official documentation of pytz<\/code>.<\/p>\nimport datetime\r\nimport pytz\r\nfor tz in pytz.all_timezones:\r\n print(tz)\r\n<\/pre>\n
month<\/code> goes first, then we have date<\/code> and finally year<\/code>. What should we do? If you are thinking about the method called strftime()<\/code>, then you are thinking in the right direction! What it does is to transform the data from naive to readable.<\/p>\nimport datetime\r\nimport pytz\r\ndt_eastern = datetime.datetime.now(tz=pytz.timezone(\"US\/Eastern\"))\r\nprint(dt_eastern.strftime(\"%B %d %Y\"))\r\n<\/pre>\n
\nIn other case, if we want to convert the string into a date, we can use a method called strptime<\/code>. For instance, we have a date called July 12, 2017<\/code> and we want to convert it to a readable but structured data. Let’s do the following:<\/p>\nimport datetime\r\nour_string = \"July 12, 2017\"\r\nresult = datetime.datetime.strptime(our_string, \"%B %d %Y\")\r\nprint(result)\r\n<\/pre>\n
<\/a>2.2 Advanced examples<\/h3>\n
datetime<\/code> module. For example, we want to understand what happened in specific date. How can we do it? Surely, we can google a lot, but Wikipedia<\/code> may seem like a better answer since it has an open API<\/code>. Let think what we can do:<\/p>\nimport datetime\r\n\r\nanswer_format = \"%m\/%d\" # as for Month and Day\r\nlink_format = \"%b_%d\"\r\nlink = \"https:\/\/en.wikipedia.org.wiki\/{}\"\r\n\r\nwhile True:\r\n\r\n answer = input(\"\"\"\r\n What date?\r\n Use the MM\/DD format or QUIT\"\"\")\r\n\r\n if answer.upper() == \"QUIT\": #in case if user inputs quit\r\n\r\n break #the program stops\r\n\r\n try:\r\n\r\n date = datetime.datetime.strptime(answer, answer_format)\r\n result = link.format(date.strftime(link_format))\r\n print(result)\r\n\r\n except ValueError:\r\n\r\n print(\"Not a valid date\") #handling exception \r\n<\/pre>\nfrom datetime import datetime\r\nimport random #in case we want a random data\r\n\r\nyear = random.randint(1917, 2017)\r\nmonth = random.randint(1, 12)\r\nday = random.randint(1, 28) #don't forget about February\r\n\r\nbirth_date = datetime(year, month, day)\r\n<\/pre>\n
\nOkay, this wasn’t too bad, right? Now, what if we want to know the current OS time and maybe have a timer? How can we do that?<\/p>\nimport datetime\r\nimport sys\r\n\r\nif __name__ == \"__main__\":\r\n\r\n while True:\r\n do = input(\"Enter:\\n\\\"T\\\" to use the timer, \\\"C\\\" to check the current time and \\\"Q\\\" to exit: \")\r\n if do.upper() == \"T\":\r\n\r\n while True:\r\n\r\n start = input(\"Enter any KEY to start:\")\r\n if start:\r\n break\r\n\r\n startTime = datetime.datetime.now()\r\n print(\"You Started at \", startTime.hour, \":\", startTime.minute, \":\", startTime.second, sep = \"\")\r\n\r\n while True:\r\n\r\n end = input(\"Enter any KEY to stop:\")\r\n if end:\r\n break\r\n\r\n endTime = datetime.datetime.now()\r\n print(\"You ended at \", endTime.hour, \":\", endTime.minute, \":\", endTime.second, sep = \"\")\r\n print(\"You took\", endTime.hour - startTime.hour, \"Hour(s),\", endTime.minute - startTime.minute, \"Minute(s),\", endTime.second - startTime.second, \"Second(s)\")\r\n\r\n elif do.upper() == \"Q\":\r\n sys.exit()\r\n\r\n elif do.upper() == \"C\":\r\n hms = datetime.datetime.now()\r\n\r\n if hms:\r\n break\r\n hms = datetime.datetime.now()\r\n print(hms.hour, \":\", hms.minute, \";\", hms.second, sep = \"\")\r\n\r\n else:\r\n print(\"That is not a valid command\")\r\n<\/pre>\n
<\/a>3. Useful tips and cool tricks<\/h2>\n
datetime<\/code> module. Let’s cover some of them. How can we access the current month name with a full month name? Well, that’s pretty easy…<\/p>\nimport datetime\r\nprint(datetime.date.today().strftime(\"%B\"))\r\n<\/pre>\n
import datetime\r\nprint(datetime.date.today().strftime(\"%A, %d %B, %Y\"))\r\n<\/pre>\n
time<\/code> module.<\/p>\nimport time\r\nfor i in range(10):\r\n time.sleep(5)\r\n print(\"Slept for 5 seconds\")\r\n<\/pre>\n
\"Slept for 5 seconds\"<\/code>. It’s pretty easy. Now, what we need here is some info showing what strftime()<\/code> and strptime()<\/code> do:<\/p>\n\n
%a<\/code> weekday as locale’s abbreviated name<\/li>\n%A<\/code> weekday as locale’s full name<\/li>\n%w<\/code> weekday as a decimal number, where 0 is Sunday and 6 is Saturday<\/li>\n%d<\/code> day of the month as a zero-padded decimal number><\/li>\n%b<\/code> month as locale’s abbreviated name<\/li>\n%B<\/code> month as locale’s full name<\/li>\n%m<\/code> month as a zero-padded decimal number<\/li>\n%y<\/code> year without century as a zero-padded decimal number<\/li>\n%Y<\/code> year without century as a decimal number<\/li>\n%H<\/code> hour(24) as a zero-padded decimal number<\/li>\n%I<\/code> hour(12) as a zero-padded decimal number<\/li>\n%p<\/code> equivalent of either AM or PM<\/li>\n%M<\/code> minute as a zero-padded number<\/li>\n%S<\/code> second as a zero-padded number<\/li>\n%z<\/code> UTC offset in the form ++HHMM or -HHMM<\/li>\n%Z<\/code> time zone name<\/li>\n%j<\/code> day of the year as a zero-padded decimal number<\/li>\n%U<\/code> week number of the year<\/li>\n%c<\/code> locale’s appropriate date and time presentation<\/li>\n%X<\/code> another date and time representation<\/li>\n<\/ul>\n<\/a>4. Summary<\/h2>\n
datetime<\/code> module. Let’s understand basic principle of the entire module, shall we?<\/p>\n