subtraction

问题 I have a script in which I subset my data according to some set time periods and wanted to subset all the records that had occurred in the last month. However if I try to subtract one month from today's date it yields an NA: > today <- Sys.Date() > today [1] "2017-03-29" > today - months(1) [1] NA I do have lubridate loaded but I think this calculation is being performed with base R. If I subtract 2 or more months it works fine: > today - months(2) [1] "2017-01-29" > today - months(3) [1]

问题 I'm looking for a library or helper class in Java that would allow me to perform date interval sum and subtractions. For example, lets's say I have the following date intervals: A = ["2015-01-01 00:00", "2015-01-20 00:00"] B = ["2015-01-05 00:00", "2015-01-10 00:00"] C = ["2015-01-11 00:00", "2015-01-14 00:00"] D = ["2015-01-19 00:00", "2015-01-25 00:00"] 1 A 20 |----------------------------------| |---------| |----------| |------------| 5 B 10 11 C 14 19 D 25 And let's say I'd like to

问题 I'm looking for a library or helper class in Java that would allow me to perform date interval sum and subtractions. For example, lets's say I have the following date intervals: A = ["2015-01-01 00:00", "2015-01-20 00:00"] B = ["2015-01-05 00:00", "2015-01-10 00:00"] C = ["2015-01-11 00:00", "2015-01-14 00:00"] D = ["2015-01-19 00:00", "2015-01-25 00:00"] 1 A 20 |----------------------------------| |---------| |----------| |------------| 5 B 10 11 C 14 19 D 25 And let's say I'd like to

问题 Is there a way of calculating two hexadecimal value without converting it to int? for example: String sHex = "f7c0"; String bHex = "040000000"; 回答1: Hexadecimal values are integers - just represented in hex instead of decimal. Can't you just do this? int sHex = 0xf7c0; int bHex = 0x040000000; If not, then you actually meant: String sHex = "f7c0"; String bHex = "040000000"; In which case, the fastest way to do this is still by converting them to integers, using something like Integer.parseInt

问题 Is there a way of calculating two hexadecimal value without converting it to int? for example: String sHex = "f7c0"; String bHex = "040000000"; 回答1: Hexadecimal values are integers - just represented in hex instead of decimal. Can't you just do this? int sHex = 0xf7c0; int bHex = 0x040000000; If not, then you actually meant: String sHex = "f7c0"; String bHex = "040000000"; In which case, the fastest way to do this is still by converting them to integers, using something like Integer.parseInt

问题 This question already has answers here : Difference between a+b and a.__add__(b) (1 answer) Python: __add__ and +, different behavior with float and integer (1 answer) Closed 16 days ago . I was expecting __add__ to work, but that's obviously not the case (in Python 3.8.0 at least): >>> 10 .__add__(5.5) NotImplemented >>> 10 .__radd__(5.5) NotImplemented The other way around works: >>> 5.5 .__add__(10) 15.5 >>> 5.5 .__radd__(10) 15.5 Why doesn't the first code work? Is there a good reason

问题 There are two lists A and B. I want to get all the elements in A but not in B. Any efficient way to do this? 回答1: You can use a list comprehension to do this for you. filtered = [i for i in A if i not in B] If the lists are both large, you might want to consider creating a set from B for faster membership lookup setB = set(B) filtered = [i for i in A if i not in setB] This solution maintains the order of A and any duplicates that exist in A . 回答2: i always like to use sets for this: set(A) -

问题 I have a data frame which looks like following and it continues up to subject 22 Beta is the dependent measure. Subject ROI Block Condition Beta 1 motor1 1 nopred_noom -2.8653 1 motor1 1 pred_noom -2.9126 1 motor1 1 nopred_om -2.8688 1 motor1 1 pred_om -2.9098 1 motor1 1 null -2.7717 1 motor1 2 nopred_noom -2.2382 1 motor1 2 pred_noom -2.0583 1 motor1 2 nopred_om -2.2207 1 motor1 2 pred_om -2.1928 1 motor1 2 null -2.1166 1 motor1 3 nopred_noom -1.5992 1 motor1 3 pred_noom -1.5493 1 motor1 3

问题 I have a data frame which looks like following and it continues up to subject 22 Beta is the dependent measure. Subject ROI Block Condition Beta 1 motor1 1 nopred_noom -2.8653 1 motor1 1 pred_noom -2.9126 1 motor1 1 nopred_om -2.8688 1 motor1 1 pred_om -2.9098 1 motor1 1 null -2.7717 1 motor1 2 nopred_noom -2.2382 1 motor1 2 pred_noom -2.0583 1 motor1 2 nopred_om -2.2207 1 motor1 2 pred_om -2.1928 1 motor1 2 null -2.1166 1 motor1 3 nopred_noom -1.5992 1 motor1 3 pred_noom -1.5493 1 motor1 3

问题 I have two text boxes which accept Start Date and End Date respectively, in format YYYY/MM/DD. I need to alert the user if he selects an end date that exceeds the start date by 50 days. Here's what I have so far: var startDate = new Date(document.getElementsByName('MYSTARTDATE').value); var endDate = new Date(document.getElementsByName('MYENDDATE').value); if ((endDate - startDate) > 50) { alert('End date exceeds specification'); return false; } Just as an example, when I select Start Date as