# # File: # ngl05p.py # # Synopsis: # Draws contours over maps. # # Category: # Contouring over maps. # # Author: # Fred Clare (based on a code by Mary Haley). # # Date of initial publication: # September, 2004 # # Description: # This example draws contours over maps of varying degrees # of complexity illustrating several map projections. # # Effects illustrated: # o Reading in several NetCDF files using Nio. # o Using several map projections: cylindrical equidistant, # orthographic, Lambert equal area. # o Contouring only over land. # o Controlling the number and spacing of contour levels. # o Changing font height and color. # o How to explicitly define contour levels. # # Output: # This examples produces four visualizations: # 1.) A simple contour over a map using the default map # projection (cylindrical equidistant). # 2.) Contouring over the oceans using an orthographic # projection and a fill pattern while coloring the # land masses with a single color. # 3.) Color contours over a specified map area using a # Lambert conformal projection. # 4.) Contouring over the U.S. with specified solid colors # for all land, U.S. water, and all other water. # Notes: # # # Import NumPy. # from __future__ import print_function import numpy, os # # Import Nio for a NetCDF reader. # import Nio # # To use the ScientificPython module to read in the netCDF file, # comment out the above "import" command, and uncomment the # import line below. # # from Scientific.IO.NetCDF import NetCDFFile # # Import Ngl support functions. # import Ngl # # Open three netCDF files and get variables. # data_dir = Ngl.pynglpath("data") cdf_file1 = Nio.open_file(os.path.join(data_dir,"cdf","941110_P.cdf"),"r") cdf_file2 = Nio.open_file(os.path.join(data_dir,"cdf","sstdata_netcdf.nc"),"r") cdf_file3 = Nio.open_file(os.path.join(data_dir,"cdf","Pstorm.cdf"),"r") # # This is the ScientificPython method for opening netCDF files. # # cdf_file1 = NetCDFFile(os.path.join(data_dir,"cdf","941110_P.cdf"),"r") # cdf_file2 = NetCDFFile(os.path.join(data_dir,"cdf","sstdata_netcdf.nc"),"r") # cdf_file3 = NetCDFFile(os.path.join(data_dir,"cdf","Pstorm.cdf"),"r") psl = cdf_file1.variables["Psl"][:] sst = cdf_file2.variables["sst"] pf = cdf_file3.variables["p"] psl_lon = cdf_file1.variables["lon"][:] psl_lat = cdf_file1.variables["lat"][:] psl_nlon = len(psl_lon) psl_nlat = len(psl_lat) sst_lon = cdf_file2.variables["lon"][:] sst_lat = cdf_file2.variables["lat"][:] sst_nlon = len(sst_lon) sst_nlat = len(sst_lat) pf_lon = cdf_file3.variables["lon"][:] pf_lat = cdf_file3.variables["lat"][:] pf_nlon = len(pf_lon) pf_nlat = len(pf_lat) # # Open a workstation. # wks_type = "png" wks = Ngl.open_wks(wks_type,"ngl05p") #----------- Begin first plot ----------------------------------------- resources = Ngl.Resources() resources.sfXCStartV = float(min(psl_lon)) resources.sfXCEndV = float(max(psl_lon)) resources.sfYCStartV = float(min(psl_lat)) resources.sfYCEndV = float(max(psl_lat)) map = Ngl.contour_map(wks,psl,resources) #----------- Begin second plot ----------------------------------------- resources.mpProjection = "Orthographic" # Change the map projection. resources.mpCenterLonF = 180. # Rotate the projection. resources.mpFillOn = True # Turn on map fill. # Fill land and leave oceans and inland water transparent. resources.mpFillColors = ["white","transparent","gray","transparent"] resources.vpXF = 0.1 # Change the size and location of the resources.vpYF = 0.9 # plot on the viewport. resources.vpWidthF = 0.7 resources.vpHeightF = 0.7 mnlvl = 0 # Minimum contour level. mxlvl = 28 # Maximum contour level. spcng = 2 # Contour level spacing. ncn = (mxlvl-mnlvl)//spcng + 1 # Number of contour levels. resources.cnLevelSelectionMode = "ManualLevels" # Define your own resources.cnMinLevelValF = mnlvl # contour levels. resources.cnMaxLevelValF = mxlvl resources.cnLevelSpacingF = spcng resources.cnLineThicknessF = 2.0 # Double the line thickness. resources.cnFillOn = True # Turn on contour level fill. resources.cnMonoFillColor = True # Use one fill color. resources.cnMonoFillPattern = False # Use multiple fill patterns. FillPatterns = numpy.zeros([ncn+1],'i')-1 FillPatterns[ncn-1:ncn+1] = 17 resources.cnFillPatterns = FillPatterns resources.cnLineDrawOrder = "Predraw" # Draw lines and filled resources.cnFillDrawOrder = "Predraw" # areas before map gets # drawn. resources.tiMainString = "~F26~{}".format(cdf_file2.title) resources.sfXCStartV = float(min(sst_lon)) # Define where contour plot resources.sfXCEndV = float(max(sst_lon)) # should lie on the map plot. resources.sfYCStartV = float(min(sst_lat)) resources.sfYCEndV = float(max(sst_lat)) resources.pmLabelBarDisplayMode = "Never" # Turn off the label bar. map = Ngl.contour_map(wks,sst[0,:,:],resources) # Draw contours over a map. #----------- Begin third plot ----------------------------------------- del resources resources = Ngl.Resources() resources.tiXAxisString = "~F25~longitude" resources.tiYAxisString = "~F25~latitude" resources.cnFillOn = True # Turn on contour fill. resources.cnLineLabelsOn = False # Turn off line labels. resources.cnInfoLabelOn = False # Turn off info label. resources.sfXCStartV = float(min(pf_lon)) # Define where contour plot resources.sfXCEndV = float(max(pf_lon)) # should lie on the map plot. resources.sfYCStartV = float(min(pf_lat)) resources.sfYCEndV = float(max(pf_lat)) resources.mpProjection = "LambertEqualArea" # Change the map projection. resources.mpCenterLonF = (pf_lon[pf_nlon-1] + pf_lon[0])/2 resources.mpCenterLatF = (pf_lat[pf_nlat-1] + pf_lat[0])/2 resources.mpLimitMode = "LatLon" # Limit the map view. resources.mpMinLonF = float(min(pf_lon)) resources.mpMaxLonF = float(max(pf_lon)) resources.mpMinLatF = float(min(pf_lat)) resources.mpMaxLatF = float(max(pf_lat)) resources.mpPerimOn = True # Turn on map perimeter. resources.pmTickMarkDisplayMode = "Never" # Turn off map tickmarks. resources.tiMainString = "~F26~January 1996 storm" # Set a title. resources.vpXF = 0.1 # Change the size and location of the resources.vpYF = 0.9 # plot on the viewport. resources.vpWidthF = 0.7 resources.vpHeightF = 0.7 resources.nglFrame = False # Don't advance frame. # # Extract the dataset from pf and scale by 0.01. # pfa = 0.01 * pf[0,:,:] # # draw contours over map. # map = Ngl.contour_map(wks,pfa,resources) # Convert pf to "mb" and txres = Ngl.Resources() txres.txFontHeightF = 0.025 # for a text string. txres.txFontColor = 4 Ngl.text_ndc(wks,"~F25~Pressure (mb)",.41,.185,txres) Ngl.frame(wks) # Advance the frame. #---------- Begin fourth plot ------------------------------------------ del resources.tiXAxisString # Delete some resources you don't del resources.tiYAxisString # need anymore. del resources.nglFrame cmap = numpy.array([[.560, .500, .700], [.300, .300, .700], \ [.100, .100, .700], [.000, .100, .700], \ [.000, .300, .700], [.000, .500, .500], \ [.000, .400, .200], [.000, .600, .000], \ [.000, 1.00, .000], [.550, .550, .000], \ [.570, .420, .000], [.700, .285, .000], \ [.700, .180, .000], [.870, .050, .000], \ [1.00, .000, .000], [0.00, 1.00, 1.00]],'f') resources.mpFillOn = True # Turn on map fill. resources.mpFillAreaSpecifiers = ["Water","Land","USStatesWater"] resources.mpSpecifiedFillColors = numpy.array([[0,1.,1.],[.7,.7,.7],[0,1.,1.]]) resources.mpAreaMaskingOn = True # Indicate we want to resources.mpMaskAreaSpecifiers = "USStatesLand" # mask land. resources.mpPerimOn = True # Turn on a perimeter. resources.mpGridMaskMode = "MaskLand" # Mask grid over land. resources.cnFillDrawOrder = "Predraw" # Draw contours first. resources.cnLevelSelectionMode = "ExplicitLevels" # Define own levels. resources.cnLevels = numpy.arange(985.,1046.,5.) resources.cnFillPalette = cmap resources.lbTitleString = "~F25~pressure (mb)" # Title for label bar. resources.cnLinesOn = False # Turn off contour lines. resources.lbOrientation = "Horizontal" # Label bar orientation. # # Extract the dataset from pf and scale by 0.01. # pfa = 0.01*pf[1,:,:] map = Ngl.contour_map(wks,pfa,resources) del map del resources #del rlist del txres Ngl.end()