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<p>Dipti,</p>
<p>Convert the year-month-day to a single calendar unit with <a
moz-do-not-send="true"
href="http://www.ncl.ucar.edu/Document/Functions/Built-in/cd_inv_calendar.shtml">cd_inv_calendar</a>
(I usually use Unix epoch-seconds, but NCL is flexible), do the
math in that space, and then use that to make a string (using <a
moz-do-not-send="true"
href="http://www.ncl.ucar.edu/Document/Functions/User_contributed/cd_string.shtml">cd_string</a>)
or recover the year-month-day as separate variables using <a
moz-do-not-send="true"
href="http://www.ncl.ucar.edu/Document/Functions/Built-in/cd_calendar.shtml">cd_calendar</a>:<br>
</p>
<p><tt>load "$NCARG_ROOT/lib/ncarg/nclscripts/contrib/cd_string.ncl"<br>
<br>
start_year = 2018<br>
start_month = 1<br>
start_day = 5<br>
delta_days = -7<br>
<br>
start_time = cd_inv_calendar( start_year, start_month,
start_day, 0, 0, 0, "seconds since 1970-1-1 00:00:00", 0 )<br>
delta = delta_days * 86400 ; Convert delta
to seconds, since our calendar units are seconds<br>
end_time = start_time + delta<br>
copy_VarAtts(start_time, end_time) ; Copy calendar information
to end_time<br>
end_string = cd_string(end_time, "%Y-%N-%D")<br>
end_time_UT = cd_calendar(end_time, -5) ; -5 gives
integer values instead of float<br>
end_year = end_time_UT(:,0)<br>
end_month = end_time_UT(:,1)<br>
end_day = end_time_UT(:,2)<br>
<br>
print(end_string)<br>
print(end_year)<br>
print(end_month)<br>
print(end_day)</tt></p>
<p><tt>**** OUTPUT ****<br>
</tt></p>
<p><tt>Variable: end_string<br>
Type: string<br>
Total Size: 8 bytes<br>
1 values<br>
Number of Dimensions: 1<br>
Dimensions and sizes: [1]<br>
Coordinates: <br>
Number Of Attributes: 1<br>
_FillValue : missing<br>
(0) 2017-12-29<br>
<br>
Variable: end_year<br>
Type: integer<br>
Total Size: 4 bytes<br>
1 values<br>
Number of Dimensions: 1<br>
Dimensions and sizes: [1]<br>
Coordinates: <br>
Number Of Attributes: 1<br>
calendar : standard<br>
(0) 2017<br>
<br>
Variable: end_month<br>
Type: integer<br>
Total Size: 4 bytes<br>
1 values<br>
Number of Dimensions: 1<br>
Dimensions and sizes: [1]<br>
Coordinates: <br>
Number Of Attributes: 1<br>
calendar : standard<br>
(0) 12<br>
<br>
Variable: end_day<br>
Type: integer<br>
Total Size: 4 bytes<br>
1 values<br>
Number of Dimensions: 1<br>
Dimensions and sizes: [1]<br>
Coordinates: <br>
Number Of Attributes: 1<br>
calendar : standard<br>
(0) 29<br>
<br>
</tt>- Walter<br>
</p>
<br>
<div class="moz-cite-prefix">On 2018-05-23 02:44, Dipti Hingmire
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAGRW+JoAi9CX=GhwRs2Q1h6q7dHKzaFY4BbLo8e0iUikNn+A_Q@mail.gmail.com">
<div dir="ltr">
<div>
<div>
<div>Dear All,<br>
<br>
</div>
I wan to plot lead lag composite plots of a set of
events/dates.<br>
<br>
</div>
Is there any inbuilt function in ncl which will provide me
date after/before specified number of days of given date?<br>
<br>
<br>
</div>
e.g. If i give 2018-01-05 as input date and I want the date 7
days before I should get 2017-12-29<br>
<div>
<div>
<div>
<div><br clear="all">
<div>
<div class="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div dir="ltr">
<div>Thanks and Regards,</div>
<div>Dipti</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
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