streamlines

[doutriaux1]

import vcs
import cdms2
import os
f= cdms2.open(os.path.join(cdat_info.get_sampledata_path(),"clt.nc"))
u=f("u")
v=f("v")
x=vcs.init()
st = vcs.createstreamline()                                                                   
x.plot(u(latitude=(-10,10),longitude=(-120,-95)),v(latitude=(-10,10),longitude=(-120,-95)),st)
x.png("blah")

[aashish24]

did it broke recently?

[danlipsa]

@doutriaux1 Try setting gm.startseed to be inside the domain.

[doutriaux1]

that did it!

st.startseed = [-100,0,0]

@danlipsa we should default it to None and manually pick a point inside the domain

[doutriaux1]

@danlipsa it's probably worth explaining in your notebook tutorial

[potter2]

I still don't get any streamlines.

import cdms2
import vcs
f1=cdms2.open('uas_6hr_reanalysis_CFSR_1998010100-1998123118.nc')
f2=cdms2.open('vas_6hr_reanalysis_CFSR_1998010100-1998123118.nc')
u=f1('uas',time=('1998-10-27','1998-10-29'),lat=(12,16),lon=(-96,-82))
v=f2('vas',time=('1998-10-27','1998-10-29'),lat=(12,16),lon=(-96,-82))
#u=f1('uas',time=('1998-10-27','1998-10-29'))
#v=f2('vas',time=('1998-10-27','1998-10-29'))
x=vcs.init()
gm=x.createstreamline()
gm.evenlyspaced = False         # only available on releases after 2.10 or on the nightly packages.
# streamlines are colored by vector magnitude
gm.coloredbyvector = True
# We want 10 glyphs(arrows) per streamline
gm.numberofglyphs = 10
gm.filledglyph = True
# we place 400 random seeds in a circle that covers the data. This means fewer seeds will be inside the data.
# The number of seeds inside the data will result in streamlines.
gm.numberofseeds = 400
gm.evenlyspaced = True # only available only on releases > 2.10 or on the nightly packages
# We want the streamline to be about one cell apart from each other
gm.separatingdistance = 1
# The seed for the first streamline. All other seeds are generated automatically
gm.startseed = [-90, 0, 0]
# create an evenly spaced streamline plot
x.plot(u, v, gm, bg=1)

[doutriaux1]

@potter2 you need to get a pint within your domain
gm.startseed = [-90, 0, 0] has a lat of 0 which is outside of your domain
you want
gm.startseed = [-90, 14,0] # [x,y,z]

[potter2]

got it. Thanks now it works

[danlipsa]

@doutriaux1 None for startseed is a good idea. This way I can leave the value as is if the user sets it. We should do that.

[danlipsa]

... If the value is None, we ca set it in the middle of the domain.

[potter2]

How do I fix the endpoints of the color bar and the colors? I know this is because of the matplotlib color maps but I just want one of the vcs colormaps.

[doutriaux1]

which colormap are you using? is it an "old" vcs colormap with reserved colors from 240 to 256?

if so

import vcs
vcs.utils.defaultColorRange = range(16,240)

[potter2]

Yes, the old one,. this doesn't work, I still get the blank on each end

sorry to be so dense on this:
import cdms2
import vcs
vcs.utils.defaultColorRange=range(16,240)
f1=cdms2.open('uas_6hr_reanalysis_CFSR_1998010100-1998123118.nc')
f2=cdms2.open('vas_6hr_reanalysis_CFSR_1998010100-1998123118.nc')
u=f1('uas',time=('1998-10-29','1998-10-29','cob'),lat=(12,24),lon=(-96,-82))
v=f2('vas',time=('1998-10-29','1998-10-29','cob'),lat=(12,24),lon=(-96,-82))
u=u/.44704
v=v/.44704
#u=f1('uas',time=('1998-10-29','1998-10-29'))
#v=f2('vas',time=('1998-10-29','1998-10-29'))
x=vcs.init()
x.setcolormap("rainbow")

u.units='mph'

gm=x.createstreamline()
gm.evenlyspaced = False # only available on releases after 2.10 or on the nightly packages.

streamlines are colored by vector magnitude

gm.coloredbyvector = True

We want 10 glyphs(arrows) per streamline

gm.numberofglyphs = 10
gm.filledglyph = True

we place 400 random seeds in a circle that covers the data. This means fewer seeds will be inside the data.

The number of seeds inside the data will result in streamlines.

gm.numberofseeds = 400
gm.evenlyspaced = True # only available only on releases > 2.10 or on the nightly packages

We want the streamline to be about one cell apart from each other

gm.separatingdistance = 1

The seed for the first streamline. All other seeds are generated automatically

gm.startseed = [-90.0, 14.0, 0]

create an evenly spaced streamline plot

x.plot(u, v, gm, bg=1,continents=4,ratio="auto")
#x.plot(u, v, gm, bg=1)
x.png('/home/potter/Desktop/honduras1.png')

[potter2]

I'm trying to make a notebook that someone could use to look at local wind (streamlines) at the time of a hurricane eg. the 1998 Honduras hurricane

[doutriaux1]

@aashish24 @scottwittenburg @danlipsa ping

[danlipsa]

@doutriaux1 Not sure what is wrong here.

[doutriaux1]

having a default to None

[danlipsa]

Oh, yes. Now I remember. Thanks!