matplotlib date formatting from UTC millisecond - datetime

I have quote data of forex currencies which I am trying to plot using matplotlib.
I can plot the data but the dates on the x-axis are in milliseconds and do not help.
I have managed to convert the dates to a datetime format, but it comes out as follows :
datetime.datetime(2015, 12, 12, 2, 0)
When i try run my code I get the following error:
line 804, in _candlestick
xy=(t - OFFSET, lower),
TypeError: unsupported operand type(s) for -: 'datetime.datetime' and 'float'
Process finished with exit code 1
My code is basically the following:
quotes = [dates, open, highest, low, close, volume]
ax = plt.subplot2grid((6, 4), (1, 0), rowspan=6, colspan=4, facecolor='#FFFFFF')
ax.xaxis.set_major_formatter(mdates.DateFormatter('%y-%m-%d %H:%M:%S'))
MOCHLV = zip(quotes[0], quotes[1], quotes[2], quotes[3], quotes[4], quotes[5])
matplotlib.finance.candlestick_ohlc(ax, MOCHLV, width=1.9, colorup='#53c156', colordown='#ff1717')
plt.ylabel('BTC/USD')
plt.xlabel('Date Hours:Minutes')
plt.show()

Related

Create a Julia Datetime from a TimePeriod and StartDate

I want to convert an Int64 representing the number of microseconds passed since 12:00:00 midnight, January 1, 0001 (0:00:00 UTC on January 1, 0001, in the Gregorian calendar) into a Julia datetime.
julia> time = Dates.Microsecond(6369175082331949400)
julia> Dates.format(time, "yyyymmdd HH:MM:SS.sss")
If you need a DateTime, just make sure you have your Int64 correctly in milliseconds, and you can use the (undocumented) UTInstant constructor, and then later add back the fractional microseconds (comment: your example number, 6369175082331949400, seems big for recent Gregorian time in microseconds, it may be nanoseconds):
julia> using Dates
julia> t = now().instant
Dates.UTInstant{Millisecond}(63694318624788 milliseconds)
julia> dump(t)
Dates.UTInstant{Millisecond}
periods: Millisecond
value: Int64 63694318624788
julia> t2 = Dates.UTInstant(Millisecond(63691750823319))
Dates.UTInstant{Millisecond}(63691750823319 milliseconds)
julia> DateTime(t2)
2019-04-24T01:00:23.319
julia> t3 = DateTime(t2)+ Dates.Microsecond(494)
2019-04-24T01:00:23.319
You can get what you want using Dates.epochms2datetime and applying an adjustment to it for your case as shown below.
Lets take datetime_value as the date we are interested in getting:
datetime_value = Dates.DateTime(2019,1,1,0,0,0)
date_start = Dates.DateTime(1,1,1,0,0,0)
date_diff = datetime_value - date_start
This gives you a value of 63681897600000 milliseconds for date_diff. Now Dates.epochms2datetime considers start of epoch as 0000-01-01T00:00:00. So we need to add 1 Year and 1 Day to the result after using Dates.epochms2datetime to arrive at our datetime value from the milliseconds value:
julia> Dates.epochms2datetime(63681897600000) + Dates.Year(1) + Dates.Day(1)
2019-01-01T00:00:00
I'm not sure I completely understand the question, as Dates.Microsecond merely returns the Int64 value of a Date or Time. However, you can create the DateTime value from a specific date and then work from there. Subtraction is allowed for DateTime values and it returns the difference in milliseconds.
using Dates
dateThen = DateTime(1, 1, 1, 0, 0, 0)
dateNow = now(UTC)
diff = dateNow - dateThen
dump(diff * 1000)
Int64 63694261047549000 (or whatever time you run it.)
Using some of the ideas provided, I came up with:
function convert_datetime(time)::DateTime
num = div(time, 100000)
remainder = rem(time, 100000)
time = DateTime(Dates.UTInstant(Millisecond(num))) + Dates.Day(1)
# time = Dates.epochms2datetime(trade.date_time/100000) + Dates.Year(1) + Dates.Day(1)
time + Dates.Microsecond(remainder)
end

Go time comparison

I'm trying to create simple function just to change time zone of a time to another (Lets assume UTC to +0700 WIB). Here is the source code. I have 2 functions, first GenerateWIB which will change just your time zone into +0700 WIB with same datetime. Second is GenerateUTC which will change given time's timezone into UTC. GenerateUTC works perfectly while another is not.
expect := time.Date(2016, 12, 12, 1, 2, 3, 4, wib)
t1 := time.Date(2016, 12, 12, 1, 2, 3, 4, time.UTC)
res := GenerateWIB(t1)
if res != expect {
fmt.Printf("WIB Expect %+v, but get %+v", expect, res)
}
The res != expect always fullfilled with this result.
WIB Expect 2016-12-12 01:02:03.000000004 +0700 WIB, but get 2016-12-12 01:02:03.000000004 +0700 WIB
But it is the same time right? Did i miss something?
There is an .Equal() method to compare dates :
if !res.Equal(expect) {
...
Quoting the doc :
Note that the Go == operator compares not just the time instant but also the Location and the monotonic clock reading. Therefore, Time values should not be used as map or database keys without first guaranteeing that the identical Location has been set for all values, which can be achieved through use of the UTC or Local method, and that the monotonic clock reading has been stripped by setting t = t.Round(0). In general, prefer t.Equal(u) to t == u, since t.Equal uses the most accurate comparison available and correctly handles the case when only one of its arguments has a monotonic clock reading.
If you look at the code for the time.Time(*) struct, you can see that this struct has three private fields :
type Time struct {
...
wall uint64
ext int64
...
loc *Location
}
and the comments about those fields clearly indicate that, depending on how the Time struct was built, two Time describing the same point in time may have different values for these fields.
Running res == expect compares the values of these inner fields,
running res.Equal(expect) tries to do the thing you expect.
(*) time/time.go source code on master branch as of oct 27th, 2020
Dates in golang must be compared with Equal method. Method Date returns Time type.
func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Time
and Time type have Equal method.
func (t Time) Equal(u Time) bool
Equal reports whether t and u represent the same time instant. Two times can be equal even if they are in different locations. For example, 6:00 +0200 CEST and 4:00 UTC are Equal. See the documentation on the Time type for the pitfalls of using == with Time values; most code should use Equal instead.
Example
package main
import (
"fmt"
"time"
)
func main() {
secondsEastOfUTC := int((8 * time.Hour).Seconds())
beijing := time.FixedZone("Beijing Time", secondsEastOfUTC)
// Unlike the equal operator, Equal is aware that d1 and d2 are the
// same instant but in different time zones.
d1 := time.Date(2000, 2, 1, 12, 30, 0, 0, time.UTC)
d2 := time.Date(2000, 2, 1, 20, 30, 0, 0, beijing)
datesEqualUsingEqualOperator := d1 == d2
datesEqualUsingFunction := d1.Equal(d2)
fmt.Printf("datesEqualUsingEqualOperator = %v\n", datesEqualUsingEqualOperator)
fmt.Printf("datesEqualUsingFunction = %v\n", datesEqualUsingFunction)
}
datesEqualUsingEqualOperator = false
datesEqualUsingFunction = true
resources
Time type documentation
Equal method documentation
time.Date

Output int32 time dimension in netCDF using xarray

Let's say I have time data that looks like this in an xarray Dataset:
ds = xr.Dataset({'time': pd.date_range('2000-01-01', periods=10)})
ds.to_netcdf('asdf.nc')
xarray's to_netcdf() method outputs the time dimension as int64:
$ ncdump -v time asdf.nc
netcdf asdf {
dimensions:
time = 10 ;
variables:
int64 time(time) ;
time:units = "days since 2000-01-01 00:00:00" ;
time:calendar = "proleptic_gregorian" ;
data:
time = 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ;
}
Because I'm working with a THREDDS server which does not support int64, I would like for these time data to be int32. Is this possible to do using xarray?
You can specify the data type of each output variable via the encoding property or the encoding keyword argument to to_netcdf. In your example, this would simply look like:
ds.to_netcdf('asdf.nc', encoding={'time': {'dtype': 'i4'}})
More information on writing encoded data can be found in the xarray documentation: http://xarray.pydata.org/en/latest/io.html#writing-encoded-data

set datetime milliseconds precision - elixir

I am trying to get a datetime which has only 3 digits in the sub-second part.
Using timex I get the following result:
iex(12)>   {:ok, date} = Timex.format(Timex.shift(Timex.local, days: 16), "{ISO:Extended}")
{:ok, "2017-04-22T09:00:44.403879+03:00"}
How can I get something like this:
{:ok, "2017-04-22T09:00:44.403+03:00"} ?
Since Elixir 1.6.0 there is now the truncate/2 function present on modules Time, DateTime and NativeDateTime for this.
Here is an example using DateTime.truncate/2
iex(1)> dt = Timex.now()
#DateTime<2018-02-16 19:03:51.430946Z>
iex(2)> dt2 = DateTime.truncate(dt, :millisecond)
#DateTime<2018-02-16 19:03:51.430Z>
DateTime has a microsecond field which is a tuple containing the value and precision. If you change the precision to 3, you'll get 3 digits in the microsecond output. I couldn't find any function in Timex which does this, but you can modify the value manually:
iex(1)> dt = %{microsecond: {us, precision}} = Timex.now
#<DateTime(2017-04-06T08:26:24.041004Z Etc/UTC)>
iex(2)> precision
6
iex(3)> dt2 = %{dt | microsecond: {us, 3}}
#<DateTime(2017-04-06T08:26:24.041Z Etc/UTC)>
iex(4)> dt2 |> Timex.format!("{ISO:Extended}")
"2017-04-06T08:26:24.041+00:00"

What format are the timestamps returned by the LinkedIn API?

LinkedIn's API returns the following value:
[creationTimestamp] => 1407247548000
It looks similar to a UNIX timestamp, but there are three "extra" zeros at the end. What format is this in, and how can I decode it?
It is a timestamp in milliseconds. Handling this is language dependent. Some languages may expect a timestamp in milliseconds, while others may expect it in seconds. Python 3, for example, expects seconds, but also handles microseconds (1000 milliseconds).
from datetime import datetime
ts = 1407247548124
dt = datetime.utcfromtimestamp(ts / 1000)
print(dt) # datetime(2014, 8, 5, 14, 5, 48, 124000)
Python 2 doesn't handle milliseconds directly (it ignores the fractional part), so you need to split the milliseconds out separately.
from datetime import datetime
ts = 14072475481234
secs, millis = divmod(ts, 1000)
dt = datetime.utcfromtimestamp(secs).replace(microsecond=millis * 1000)
print(dt) # datetime(2014, 8, 5, 14, 5, 48, 124000)

Resources