# # File: # NUG_rectilinear_vector_PyNGL.py # # Synopsis: # Illustrates creating vectors over contours over a map # # Categories: # vector plots # contour plots # # Author: # Karin Meier-Fleischer # # Date of initial publication: # June 2016 # # Description: # This example shows how to create vectors over contours over # a map using rectilinear data. # # Effects illustrated: # o Coloring vectors based on magnitude # o Coloring vectors based on temperature # o Drawing straight vectors # o Drawing curly vectors # o Zooming in on a map # # Output: # Two visualizations are produced: one over a global map and one over the United States # # Notes: The data for this example can be downloaded from # http://www.ncl.ucar.edu/Document/Manuals/NCL_User_Guide/Data/ # """ NCL User Guide Python Example: NUG_rectilinear_vector_PyNGL.py - vectors on global map, colored - vectors colored by temperature - curly vectors - rectilinear data 2015-06-04 kmf """ from __future__ import print_function import Ngl,Nio,os #-- define variables diri = "./" #-- data directory fname = "rectilinear_grid_2D.nc" #-- data file name #-- open file and read variables f = Nio.open_file(os.path.join(diri, fname), "r") #-- open data file temp = f.variables["tsurf"][0,:,:] #-- first time step u = f.variables["u10"][0,:,:] #-- first time step v = f.variables["v10"][0,:,:] #-- first time step lat = f.variables["lat"][:] #-- all latitudes lon = f.variables["lon"][:] #-- all longitudes nlon = len(lon) #-- number of longitudes nlat = len(lat) #-- number of latitudes #-- open a workstation wkres = Ngl.Resources() #-- generate an resources object for workstation wkres.wkWidth = 2500 #-- plot resolution 2500 pixel width wkres.wkHeight = 2500 #-- plot resolution 2500 pixel height wks_type = "png" #-- graphics output type wks_name = os.path.basename(__file__).split(".")[0] wks = Ngl.open_wks(wks_type,wks_name,wkres) #-- create 1st plot: vectors on global map res = Ngl.Resources() res.tiMainString = "~F25~Wind velocity vectors" #-- title string res.tiMainFontHeightF = 0.024 #-- decrease title font size res.mpLimitMode = "Corners" #-- select a sub-region res.mpLeftCornerLonF = float(lon[0]) #-- left longitude value res.mpRightCornerLonF = float(lon[nlon-1]) #-- right longitude value res.mpLeftCornerLatF = float(lat[0]) #-- left latitude value res.mpRightCornerLatF = float(lat[nlat-1]) #-- right latitude value res.mpPerimOn = True #-- turn on map perimeter res.vcMonoLineArrowColor = False #-- draw vectors in color res.vcMinFracLengthF = 0.33 #-- increase length of vectors res.vcMinMagnitudeF = 0.001 #-- increase length of vectors res.vcRefLengthF = 0.045 #-- set reference vector length res.vcRefMagnitudeF = 20.0 #-- set reference magnitude value res.vcLineArrowThicknessF = 6.0 #-- make vector lines thicker (default: 1.0) res.vcLevelPalette = "ncl_default" #-- choose color map res.pmLabelBarDisplayMode = "Always" #-- turn on a labelbar res.lbOrientation = "Horizontal" #-- labelbar orientation res.lbLabelFontHeightF = 0.008 #-- labelbar label font size res.lbBoxMinorExtentF = 0.22 #-- decrease height of labelbar boxes res.vfXArray = lon[::3] #-- longitude values, subscript every 3rd value res.vfYArray = lat[::3] #-- latitude values, subscript every 3rd value map1 = Ngl.vector_map(wks,u[::3,::3],v[::3,::3],res) #-- draw a vector plot, subscript every 3rd value #-- create 2nd plot: sub-region colored by temperature variable tempa = (temp-273.15)*9.0/5.0+32.0 #-- convert from Kelvin to Fahrenheit res.mpLimitMode = "LatLon" #-- change the area of the map res.mpMinLatF = 18.0 #-- minimum latitude res.mpMaxLatF = 65.0 #-- maximum latitude res.mpMinLonF = -128. #-- minimum longitude res.mpMaxLonF = -58. #-- minimum longitude res.mpFillOn = True #-- turn on map fill res.mpLandFillColor = "gray45" #-- change land color to gray res.mpOceanFillColor = "transparent" #-- change color for oceans and inlandwater res.mpInlandWaterFillColor = "transparent" #-- set ocean/inlandwater color to transparent res.mpGridMaskMode = "MaskNotOcean" #-- draw grid over ocean, not land res.mpGridLineDashPattern = 2 #-- grid dash pattern res.mpOutlineBoundarySets = "GeophysicalAndUSStates" #-- outline US States res.vcFillArrowsOn = True #-- fill the vector arrows res.vcMonoFillArrowFillColor = False #-- draw vectors with colors res.vcFillArrowEdgeColor = "black" #-- draw the edges in black res.vcLineArrowColor = "black" #-- draw the edges in black res.vcGlyphStyle = "CurlyVector" #-- draw nice curly vectors res.vcLineArrowThicknessF = 5.0 #-- make vector lines thicker (default: 1.0) res.tiMainString = "~F25~Wind velocity vectors" #-- title string res.lbTitleString = "TEMPERATURE (~S~o~N~F)" #-- labelbar title string res.lbTitleFontHeightF = 0.010 #-- labelbar title font size res.lbBoxMinorExtentF = 0.18 #-- decrease height of labelbar boxes res.vfXArray = lon res.vfYArray = lat map2 = Ngl.vector_scalar_map(wks,u,v,tempa,res) #-- the end Ngl.end()