basic.py

#!/usr/bin/python
# Filename: basic.py
#
# Code by Martin Jucker, distributed under an MIT License
# Any publication benefitting from this piece of code should cite
# Jucker, M 2014. Scientific Visualisation of Atmospheric Data with ParaView.
# Journal of Open Research Software 2(1):e4, DOI: http://dx.doi.org/10.5334/jors.al
#
# Python interface for ParaView (www.paraview.org). Reads netCDF file on an arbitrary grid, including logarithmic coordinates and time evolution (if present). netCDF file needs to loosely correspond to Climate and Forecast (FC) conventions (https://en.wikipedia.org/wiki/Climate_and_Forecast_Metadata_Conventions).
# Also provides helper functions for common operations.

##### needed modules: paraview.simple, math #########################
from paraview.simple import *
from math import pi,log10

# some global constants
strPi = str(pi)[0:7]

##### define auxiliary functions ##################################

# define logarithmic coordinate conversion
def ConvertLogCoordString(pString, basis=1e3):
    """Logarithmic coordinate conversion in string form for Calculator filter.

    Output is the string to be used inside the Calculator filter:
    pString -- the coordinate to convert
    basis   -- basis (surface) pressure to normalize
    """
    expression = 'abs(log10(abs(' + pString + ')/' + str(basis) + '))'
    return expression

# do the coordinate conversion inside a Calculator
def Cart2Log(src=GetActiveSource(), ratios=[1,1,1], logCoords=[], basis=[]):
    """Convert between logarithmic and linear coordinates. Also applies aspect ratio correction.

    Adds a Calculator filter to the pipeline
    src       -- filter in pipeline to attach to
    ratios    -- multiplicative factor for coordinates - must be same length as # of dimensions
    logCoords -- indices (0 based) of coordinates to be converted
    basis     -- basis to normalize argument to logarithm (ie defines origin) - must be length 1 or same as logCoords
    """
    nVec=['iHat*','jHat*','kHat*']
    coords=['coordsX','coordsY','coordsZ']
    cFun=coords[:]
    pFun=''
    for pp in range(len(logCoords)):
        ci = logCoords[pp]
        if len(basis) == 1:
            bas = basis[0]
        else:
            bas = basis[pp]
        cFun[ci] = ConvertLogCoordString(coords[ci], bas)
    for ii in range(len(ratios)):
        if ratios[ii] != 1.0:
            pFun += nVec[ii]+cFun[ii] + '*'+str(ratios[ii]) + ' + '
        else:
            pFun += nVec[ii]+cFun[ii] + ' + '
    calc=Calculator(src)
    calc.Function = pFun[:-3]
    calc.CoordinateResults = 1
    return calc
#
def Cart2Spherical(radius=1.0, src=GetActiveSource()):
    """Convert Cartesian to spherical coordinates. 

    Assumes X coordinate is longitude, Y coordinate latitude, Z coordinate vertical.
    Adds Calculator filter to the pipeline.
    radius -- radius of the sphere, where coordZ = basis
    src    -- filter in pipeline to attach to
    """
    calc=Calculator(src)
    strRad = str(radius)
    try:
        calc.Function = 'iHat*('+strRad+'+coordsZ)*cos(coordsY*'+strPi+'/180)*cos(coordsX*'+strPi+'/180) + jHat*('+strRad+'+coordsZ)*cos(coordsY*'+strPi+'/180)*sin(coordsX*'+strPi+'/180) + kHat*('+strRad+'+coordsZ)*sin(coordsY*'+strPi+'/180)'
    except:
        calc.Function = 'iHat*'+strRad+'*cos(coordsY*'+strPi+'/180)*cos(coordsX*'+strPi+'/180) + jHat*'+strRad+'*cos(coordsY*'+strPi+'/180)*sin(coordsX*'+strPi+'/180) + kHat*'+strRad+'*sin(coordsY*'+strPi+'/180)'
    calc.CoordinateResults = 1
    RenameSource('Cart2Spherical',calc)
    return calc

# apply aspect ratios to grid. This might already be done in Cart2Log
def GridAspectRatio(ratios, src=GetActiveSource()):
    """Adjust aspect ratio of Cartesian grid: multiplies ratios x coordinates.

    Adds Calculator filter to the pipeline.
    ratios -- 2- or 3-vector with multiplicative factors for each spatial coordinate
    """
    calc=Calculator(src)
    calc.Function = 'iHat*'+str(ratios[0])+'*coordsX + jHat*'+str(ratios[1])+'*coordsY + kHat*'+str(ratios[2])+'*coordsZ'
    calc.CoordinateResults = 1
    return calc

# transform coordinates: logarithmic, aspect ratio
def TransformCoords(src=GetActiveSource(), aspectRatios=[1,1,1], logCoords=[], basis=[], reverseCoords=[], revCenter=[]):
    """Transform the coordinates depending on whether or not there are logarithmic coordinates"""
    if len(reverseCoords)>0:
        nVec = ['iHat*','jHat*','kHat*']
        nCoor= ['X','Y','Z']
        revCoor = Calculator(src)
        rFun = ''
        for dim in range(3):
            if dim in reverseCoords or -dim in reverseCoords:
                for d in range(len(reverseCoords)):
                    if dim == abs(reverseCoords[d]):
                        rd = d
                if reverseCoords[rd]<0:
                    coorSign = '+'
                else:
                    coorSign = '-'
                rFun += ' +'+nVec[dim]+'('+str(revCenter[rd])+coorSign+'coords'+nCoor[dim]+')'
            else:
                rFun += ' +'+nVec[dim]+'coords'+nCoor[dim]
        revCoor.Function = rFun[2:]
        revCoor.CoordinateResults = 1
        src = revCoor
    if len(logCoords)>0 :
        transCoor = Cart2Log(src=src,ratios=aspectRatios,logCoords=logCoords,basis=basis)
    else:
        transCoor = GridAspectRatio(ratios=aspectRatios, src=src)
    return transCoor

#
def MakeSelectable(src=GetActiveSource()):
    """Make filter selectable in pipeline browser, but don't show it."""
    rep=Show(src)
    rep.Visibility=0


######### read in data, redefine pressure coordinates and change aspect ratio ###############

def LoadData( fileName, ncDims=['lon','lat','pfull'], aspectRatios=[1,1,1], logCoords=[], basis=[], reverseCoords=[], revCenter=[], replaceNaN=True ):
    """Load netCDF file, convert coordinates into useful aspect ratio.

    Adds file output_nc, and Calculator LogP or Calculator AspRat to the pipeline
    
    INPUTS:
        fileName      -- full path and file name of data to be read
        ncDims        -- names of the dimensions within the netCDF file. Time should be excluded. Ordering [x,y,z]
        aspectRatios  -- how to scale coordinates [xscale,yscale,zscale]. Z coordinate is scaled after applying log10 for logarithmic axes
        logCoords     -- index/indices of dimension(s) to be logarithmic, set to [] if no log coordinates
        basis         -- basis to normalize argument to logarithm (ie defines origin). List of same length as logCoords
        reverseCoords -- index/indices of dimension(s) to be reversed, set to [] if none to be reversed
        revCenter     -- center of reversal if reverseCoords is not empty. List of same length as logCoords
        replaceNaN    -- whether or not to replace the FillValue with NaNs
    OUTPUTS:
        output_nc     -- netCDF reader object with the file data as read
        transCoor     -- Calculator filter corresponding to the transformed coordinates
    """ 
    # outputDimensions must be in same sequence as in netCDF file, except time (e.g. ['pfull','lat','lon'] ). This is usually the "wrong" way round. Thus, we invert it here
    outputDimensions = ncDims[::-1]
    output_nc = NetCDFReader( FileName=[fileName] )

    if len(outputDimensions)>0 :
        outDims = '('+ outputDimensions[0]
        for dim in range(1,len(outputDimensions)):
            outDims = outDims + ', ' + outputDimensions[dim]
        outDims += ')'
        output_nc.Dimensions = outDims
    
    output_nc.SphericalCoordinates = 0
    output_nc.OutputType = 'Unstructured'
    output_nc.ReplaceFillValueWithNan = replaceNaN
    MakeSelectable()
    RenameSource(fileName,output_nc)
    
    transCoor = TransformCoords(src=output_nc,aspectRatios=aspectRatios,logCoords=logCoords,basis=basis,reverseCoords=reverseCoords,revCenter=revCenter)
    MakeSelectable()
	
    if len(logCoords)>0 :
        RenameSource('LogCoor',transCoor)
    else:
        RenameSource('TransCoor',transCoor)
    return output_nc,transCoor

######## convert 2D into 3D data using a variable as third dimension ##############

def Make3D( expandVar, expandDir='z', aspectRatios=[1,1,1], logCoords=[], basis=1e3, src=GetActiveSource() ):
    """Expand any 2D dataset into 3D with the values of a field.
        
        Make3D takes a 2D dataset, and adds a third dimension corresponding to a data field.
        
        INPUTS:
            expandVar    -- name of the variable to use as third dimension
            expandDir    -- direction in which to expand {'x','y','z'}. Make it negative for expanding in opposite direction: {'-x','-y','-z'}
            aspectRatios -- how to scale coordinates [xscale,yscale,zscale]. Z coordinate is scaled after applying log10 for logarithmic axes
            logCoords    -- index/indices of dimension(s) to be logarithmic
            basis        -- basis to normalize argument to logarithm (ie defines origin). List of same length as logCoords
            src          -- source fiter to attach to
        OUPUTS:
            trans3d      -- a Calculator filter with the transformed 3D field
    """
    make3d = Calculator(src)
    sign = '+'
    if expandDir[0] == '-':
        sign = '-'
    if expandDir.lower()[-1] == 'x':
        make3d.Function = sign+'iHat*'+expandVar+' + jHat*coordsY + kHat*coordsZ)'
    elif expandDir.lower()[-1] == 'y':
        make3d.Function = 'iHat*coordsX '+sign+' jHat*'+expandVar+' + kHat*coordsZ)'
    elif expandDir.lower()[-1] == 'z':
        make3d.Function = 'iHat*coordsX + jHat*coordsY '+sign+' kHat*'+expandVar
    else:
        raise Exception("Make3D: expandDir has to be one of x,y,z, but is "+expandDir)
    make3d.CoordinateResults = 1

    trans3d = TransformCoords(src=make3d,aspectRatios=aspectRatios,logCoords=logCoords,basis=basis)
    return trans3d

######## some other usefull tools #################################################

# transform winds from SI to plot units
def CartWind2Sphere(src=GetActiveSource(), zonalComponentName='ucomp', meridionalComponentName='vcomp', secondsPerTimeStep=86400, verticalComponentName='none', ratios=[1,1,1], vertAsp=1 ):
    """Convert wind components from m/s to lat/timeStep, lon/timeStep, z/timeStep, and store it as vector W. This is, naturally, specific to spherical geometry, and assumes that coordsX = longitude [degrees], coordsY = latitude [degrees], and coordsZ = vertical coordinate.

    Works with both pressure and height velocity, as long as vertAsp = [initial vertical range]/[present vertical range] is correct.
    INPUTS:
        src                     -- filter in pipeline to attach to
        zonalComponentName      -- name of zonal wind component in pipeline
        meridionalComponentName -- name of meridional wind component in pipeline
        secondsPerTimeStep      -- duration of time step in seconds: 86400 for daily
        verticalComponentName   -- name of vertical component, or 'none'
        ratios                  -- Corrections to actually plotted axes
        vertAsp                 -- factor for vertical unit conversion = [initial vertical range]/[present vertical range(transformed)]. Only needed if there is a vertical component
    OUTPUTS:
        Adds two Calculators to the pipeline:
        W     -- wind vector calculation
        normW -- magnitude of wind vector
        Adds two slices to the pipeline to remove division by zero close to poles:
        clipS -- remove south pole
        clipN -- remove north pole
    """
    W=Calculator(src)
    if verticalComponentName != 'none' :
        W.Function = '(' + \
        'iHat*'+zonalComponentName+'/(6.28*6.4e6*cos(coordsY/'+str(ratios[1])+'*'+strPi+'/180))*360 +' + \
        'jHat*'+meridionalComponentName+'/('+strPi+'*6.4e6)*180 +' + \
        'kHat*'+verticalComponentName+'/'+vertAsp + \
        ')*'+str(secondsPerTimeStep) 
    else:
        W.Function =  '(' + \
        'iHat*'+zonalComponentName+'/(6.28*6.4e6*cos(coordsY/'+str(ratios[1])+'*'+strPi+'/180))*360 +' + \
        'jHat*'+meridionalComponentName+'/('+strPi+'*6.4e6)*180' + \
        ')*'+str(secondsPerTimeStep)  
    W.ResultArrayName = 'W'
    RenameSource('CartWind2Sphere',W)
    MakeSelectable(W)
    # add the magnitdue of the wind vector, i.e wind strength. nice to have for color, threshold, glyph filters later on
    norm = Calculator(W)
    norm.Function = 'mag(W)'
    norm.ResultArrayName = 'normW'
    RenameSource('normW',norm)
    MakeSelectable(norm)
    # conversion invloves a division by zero over the poles. to avoid large numbers, cut away anything higher than 80 degrees
    clipS = Clip(norm)
    clipS.ClipType = 'Plane'
    clipS.ClipType.Normal = [0.0, 1.0, 0.0]
    clipS.ClipType.Origin  = [0.0, -80.0*ratios[1], 0.0]
    RenameSource('clipS',clipS)
    MakeSelectable(clipS)
    clipN = Clip(clipS)
    clipN.ClipType = 'Plane'
    clipN.ClipType.Normal = [0.0,-1.0, 0.0]
    clipN.ClipType.Origin  = [0.0, 80.0*ratios[1], 0.0]
    RenameSource('clipN',clipN)
    MakeSelectable(clipN)
    return W,norm,clipS,clipN

# extract the boundaries of a filter
def ExtractBounds(src=GetActiveSource()):
    """Return the axis extremities (bounds) of any source filter
        
        Inputs:
        src    - filter to extract bounds of
        Outputs:
        bounds - list of (xmin,xmax [,ymin,ymax [,zmin,zmax]])"""
    bounds = src.GetDataInformation().GetBounds()
    return bounds

## working with a spherical geometry: conversion functions
def Sphere2xyz(coords, lam, phi):
    """Compute (x,y,z) from coords=(r,lam,phi) or r,lam,phi, where lam=0 at the Equator, -90 <= lam <= 90 (latitude),
        and phi=0 along x-axis, 0 <= phi <= 360 (longitude)
        Also computes the normal along the radial direction (useful for placing and orienting the camera).
        
        INPUTS:
            coords - list of (radius,lambda,phi) or radius
            lam    - lambda (declination, latitude) if coords is radius
            phi    - phi (azimuth, longitude) if coords is radius
        OUTPUTS:
            xyzPos - list of corresponding (x,y,z)
            normal - list of (xn,yn,zn) along radial direction
    """
    from math import pi,sin,cos
    if len(coords) == 3:
        rr=coords[0];lam=coords[1];phi=coords[2]
    elif len(coords) == 1:
        rr=coords
    else:
        raise Exception("Sphere2xyz: coords has to be a list of length 3 (r,lambda,phi), or a scalar (radius)")
    xyzPos = [rr*cos(lam*pi/180)*cos(phi*pi/180),rr*cos(lam*pi/180)*sin(phi*pi/180),rr*sin(lam*pi/180)]
    rr=rr+1
    p1     = [rr*cos(lam*pi/180)*cos(phi*pi/180),rr*cos(lam*pi/180)*sin(phi*pi/180),rr*sin(lam*pi/180)]
    normal = []
    for i in range(len(p1)):
        normal.append(p1[i] - xyzPos[i])
    return xyzPos,normal
#
def xyz2Sphere(coords, y, z):
    """Compute (r,lam,phi) from coords=(x,y,z) or x,y,z, where lam=0 at the Equator, -90 <= lam <= 90 (latitude),
        and phi=0 along x-axis, 0 <= phi <= 360 (longitude)
        
        INPUTS:
            coords - list of (x,y,z) or x
            y      - y coordinate if coords is x
            z      - z coordinate if coords is x
        OUTPUTS:
            sphPos - list of corresponding (r,lam,phi)
    """
    from math import sqrt,pi,sin,cos,asin,atan
    if len(coords == 3):
        x=coords[0];y=coords[1];z=coords[2]
    elif len(coords) == 1:
        x = coords
    else:
        raise Exception("xyz2Sphere: coords has to be a list of length 3 (x,y,z), or a scalar (x)")
    r   = sqrt(x*x + y*y + z*z)
    if x > 0:
        phi = atan(y/x)
    elif x < 0:
        phi = pi + atan(y/x)
    elif x == 0 and y > 0:
        phi = 0.5*pi
    elif x == 0 and y < 0:
        phi = 1.5*pi
    lam = asin(z/r)
    return (r,lam*180/pi,phi*180/pi)

## some simple helper functions
#
def DeleteAll():
    """Delete all objects in the pipeline browser."""
    for src in GetSources().values():
        Delete(src)
#
def HideAll():
    """Make all objects in pipeline browser invisible."""
    for src in GetSources().values():
    	Hide(src)
#
def ShowAll():
    """Make all objects in pipeline browser visible."""
    for src in GetSources().values():
        Show(src)