from numpy import *

"""
Code for hierarchical clustering, modified from 
Programming Collective Intelligence by Toby Segaran 
(O'Reilly Media 2007, page 33). 
"""

class cluster_node:
    def __init__(self,vec,left=None,right=None,distance=0.0,id=None,count=1):
        self.left=left
        self.right=right
        self.vec=vec
        self.id=id
        self.distance=distance
        self.count=count #only used for weighted average 

def L2dist(v1,v2):
    return sqrt(sum((v1-v2)**2))
    
def L1dist(v1,v2):
    return sum(abs(v1-v2))

# def Chi2dist(v1,v2):
#     return sqrt(sum((v1-v2)**2))

def hcluster(features,distance=L2dist):
    #cluster the rows of the "features" matrix
    distances={}
    currentclustid=-1

    # clusters are initially just the individual rows
    clust=[cluster_node(array(features[i]),id=i) for i in range(len(features))]

    while len(clust)>1:
        lowestpair=(0,1)
        closest=distance(clust[0].vec,clust[1].vec)
    
        # loop through every pair looking for the smallest distance
        for i in range(len(clust)):
            for j in range(i+1,len(clust)):
                # distances is the cache of distance calculations
                if (clust[i].id,clust[j].id) not in distances: 
                    distances[(clust[i].id,clust[j].id)]=distance(clust[i].vec,clust[j].vec)
        
                d=distances[(clust[i].id,clust[j].id)]
        
                if d<closest:
                    closest=d
                    lowestpair=(i,j)
        
        # calculate the average of the two clusters
        mergevec=[(clust[lowestpair[0]].vec[i]+clust[lowestpair[1]].vec[i])/2.0 \
            for i in range(len(clust[0].vec))]
        
        # create the new cluster
        newcluster=cluster_node(array(mergevec),left=clust[lowestpair[0]],
                             right=clust[lowestpair[1]],
                             distance=closest,id=currentclustid)
        
        # cluster ids that weren't in the original set are negative
        currentclustid-=1
        del clust[lowestpair[1]]
        del clust[lowestpair[0]]
        clust.append(newcluster)

    return clust[0]


def extract_clusters(clust,dist):
    # extract list of sub-tree clusters from hcluster tree with distance<dist
    clusters = {}
    if clust.distance<dist:
        # we have found a cluster subtree
        return [clust] 
    else:
        # check the right and left branches
        cl = []
        cr = []
        if clust.left!=None: 
            cl = extract_clusters(clust.left,dist=dist)
        if clust.right!=None: 
            cr = extract_clusters(clust.right,dist=dist)
        return cl+cr 
        
def get_cluster_elements(clust):
    # return ids for elements in a cluster sub-tree
    if clust.id>0:
        # positive id means that this is a leaf
        return [clust.id]
    else:
        # check the right and left branches
        cl = []
        cr = []
        if clust.left!=None: 
            cl = get_cluster_elements(clust.left)
        if clust.right!=None: 
            cr = get_cluster_elements(clust.right)
        return cl+cr


def printclust(clust,labels=None,n=0):
    # indent to make a hierarchy layout
    for i in range(n): print ' ',
    if clust.id<0:
        # negative id means that this is branch
        print '-'
    else:
        # positive id means that this is an endpoint
        if labels==None: print clust.id
        else: print labels[clust.id]
    
    # now print the right and left branches
    if clust.left!=None: printclust(clust.left,labels=labels,n=n+1)
    if clust.right!=None: printclust(clust.right,labels=labels,n=n+1)



def getheight(clust):
    # Is this an endpoint? Then the height is just 1
    if clust.left==None and clust.right==None: return 1
    
    # Otherwise the height is the same of the heights of
    # each branch
    return getheight(clust.left)+getheight(clust.right)

def getdepth(clust):
    # The distance of an endpoint is 0.0
    if clust.left==None and clust.right==None: return 0
    
    # The distance of a branch is the greater of its two sides
    # plus its own distance
    return max(getdepth(clust.left),getdepth(clust.right))+clust.distance
      
      
from PIL import Image,ImageDraw
 
def drawdendrogram(clust,imlist,jpeg='clusters.jpg'):
    # height and width
    h=getheight(clust)*20
    w=1200
    depth=getdepth(clust)
    
    # width is fixed, so scale distances accordingly
    scaling=float(w-150)/depth
    
    # Create a new image with a white background
    img=Image.new('RGB',(w,h),(255,255,255))
    draw=ImageDraw.Draw(img)
    
    draw.line((0,h/2,10,h/2),fill=(255,0,0))    
    
    # Draw the first node
    drawnode(draw,clust,10,(h/2),scaling,imlist,img)
    img.save(jpeg)

def drawnode(draw,clust,x,y,scaling,imlist,img):
    if clust.id<0:
        h1=getheight(clust.left)*20
        h2=getheight(clust.right)*20
        top=y-(h1+h2)/2
        bottom=y+(h1+h2)/2
        # Line length
        ll=clust.distance*scaling
        # Vertical line from this cluster to children    
        draw.line((x,top+h1/2,x,bottom-h2/2),fill=(255,0,0))    
        
        # Horizontal line to left item
        draw.line((x,top+h1/2,x+ll,top+h1/2),fill=(255,0,0))    
        
        # Horizontal line to right item
        draw.line((x,bottom-h2/2,x+ll,bottom-h2/2),fill=(255,0,0))        
        
        # Call the function to draw the left and right nodes    
        drawnode(draw,clust.left,x+ll,top+h1/2,scaling,imlist,img)
        drawnode(draw,clust.right,x+ll,bottom-h2/2,scaling,imlist,img)
    else:   
        # If this is an endpoint, draw a thumbnail image
        nodeim = Image.open(imlist[clust.id])
        nodeim.thumbnail((20,20))
        ns = nodeim.size
        img.paste(nodeim,(x,y-ns[1]//2,x+ns[0],y+ns[1]-ns[1]//2))