New answers tagged date-and-time
11
It took me quite a while, but finally, here's a visualization of the perigee of Flamsteed's comet:
I should first note two things: first, some of the needed data for computing the orbit of comet C/1683 O1 was missing in AstronomicalData["CometC1683O1", "Properties"], and I had to pull information from external sources to supplement the information ...
4
AbsoluteTime is faster on DateLists as compared to arbitrary DateStrings. Since the date format is known in this case, converting the strings to DateLists first gives a speed improvement of a factor of 10:
AbsoluteTime /@ (ToExpression /@ (StringSplit[#, {" ", "-", ":"}] & /@ dateStrings));
Not as fast as the java programming variant, but good enough ...
1
ReadList thinks your file has lists of 4, not 5, elements; it views the minutes and the "m" as a single element. The following will import the lists.
dd = ReadList["/tmp/data8.txt", {Word, Word, Number, Character}]
{{"Apr-09", "-1m", 47, "s"}, {"Apr-11", "-1m", 15, "s"}, {"Apr-12",
"-0m", 59, "s"}, {"Apr-13", "-0m", 44, "s"}, {"Apr-14", "-0m", ...
9
You can get about 100 times faster by using Java, without any particular tuning, but you will have to provide the date format explicitly. Here is the solution based on Java reloader.
Implementation
Load the Java reloader
Compile the following class:
JCompileLoad@
"
import java.text.ParseException;
import java.text.SimpleDateFormat;
import ...
1
You are not using the functions correctly
In[9]:= DateString[]
Out[9]= "Tue 30 Apr 2013 09:37:20"
while
In[10]:= DateString[TimeZone -> 0]
Out[10]= "Tue 30 Apr 2013 07:37:26"
and
In[33]:= AstronomicalData["Sun", {"NextRiseTime", {2012, 10, 8, 6, 0,
0}}, TimeZone -> 1]
Out[33]= {2012, 10, 8, 6, 35, 31.7528}
In[34]:= AstronomicalData["Sun", ...
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