#
#  File:
#    TRANS_scatter.py
#
#  Synopsis:
#    Illustrates how to create a scatter plot
#
#  Categories:
#    xy plot
#    polymarker
#
#  Author:
#    Karin Meier-Fleischer, based on NCL example
#  
#  Date of initial publication:
#    September 2018
#
#  Description:
#    This example shows how to create a scatter plot.
#
#  Effects illustrated:
#    o  Create random data
#    o  Drawing a scatter plot
#    o  polymarker
# 
#  Output:
#    A single visualization is produced.
#
#  Notes: The data for this example can be downloaded from 
#    http://www.ncl.ucar.edu/Document/Manuals/NCL_User_Guide/Data/
#   
'''
  Transition Guide Python Example: TRANS_scatter.py
  
  -  Use different markers
  -  Use different marker colors
  -  Drawing a legend with markers and labels inside plot

  18-09-07  kmf
'''
import numpy as np
import Ngl
import os

#-- generate random data
npts  = 100
x     = np.arange(1,npts,1)
data1 = np.random.uniform(0.1,50,npts)
data2 = np.random.uniform(0.1,50,npts)

#-- create data array containing data1 and data2
data = np.zeros([2,npts],np.float32)
data[0,:] = data1
data[1,:] = data2

#-- set explicit labels for legend
labels = ["data 1","data 2"]

#-- open workstation
wks =  Ngl.open_wks("png",os.path.basename(__file__).split('.')[0])

#-- set resources
res                  = Ngl.Resources()
res.nglPointTickmarksOutward = True         #-- point tickmarks outward

res.tiMainString     = "Marker Plot"        #-- add title

#-- make plot space larger to have enough space for legend 
res.trYMinF          = min(data1)-20.       #-- y-axis minimum
res.trYMaxF          = max(data1)+20.       #-- y-axis maximum
res.trXMinF          = min(x)-5.            #-- y-axis minimum
res.trXMaxF          = max(x)+5.            #-- y-axis maximum

res.tmLabelAutoStride = True                #-- use nice tick mark labels

res.xyMarkLineModes  = ["Markers","Markers"]#-- set mark line mode
res.xyMarkers        = [10,16]              #-- choose marker types 
res.xyMarkerColors   = ["red","blue"]       #-- choose marker colors

res.lgJustification  = "TopRight"           #-- position of legend
res.lgLabelFontHeightF = 0.01               #-- legend label font size
res.lgItemOrder      = [1,0]                #-- reverse the legend
res.xyExplicitLabels = labels               #-- use explicit legend labels

res.pmLegendDisplayMode = "Always"          #-- display legend always
res.pmLegendWidthF   = 0.10                 #-- legend width
res.pmLegendHeightF  = 0.06                 #-- legend height
res.pmLegendOrthogonalPosF = -0.22          #-- move legend up
res.pmLegendParallelPosF = 0.98             #-- move legend right

#-- create the plot
plot = Ngl.xy(wks,x,data,res)