def _readFile(self, sldir, fileName, sep):
        '''
        Private method that reads in the header and column data.

        '''

        if sldir.endswith(os.sep):
            fileName = str(sldir)+str(fileName)
        else:
            fileName = str(sldir)+os.sep+str(fileName)


        fileLines=[] #list of lines in the file
        header=[]    #list of Header lines
        dataCols=[]  #Dictionary of data column names
        data=[]      #List of Data lists
        cols=[]      #List of column names

        f=open(fileName,'r')
        fileLines=f.readlines()
        i=0
        if self.datatype != 'trajectory':

            while i<len(fileLines):
                if fileLines[i].startswith(self.header_char):
                    tmp=fileLines[i].lstrip(self.header_char)
                    header.append(tmp.strip())
                else:
                    break
                i+=1

            cols=fileLines[i].split(sep)

            tmp=[]
            tmp1=[]
            for j in range(len(cols)):
                tmp1=cols[j].strip()
                if tmp1 !='':
                    tmp.append(tmp1)
            cols=tmp
            i+=1
        else:
            header={}
            while fileLines[i].startswith('#') or '=' in fileLines[i]:
                if fileLines[i].startswith('#') and cols==[]:
                    cols=fileLines[i].strip('#')
                    cols=cols.strip()
                    cols=cols.split()
                elif fileLines[i].startswith('#'):
                    tmp1=fileLines[i].strip('#')
                    tmp1=tmp1.strip()
                    self.headerLines.append(tmp1)
                elif not fileLines[i].startswith('#'):
                    tmp=fileLines[i].split('=')
                    tmp[0]=tmp[0].strip()
                    tmp[1]=tmp[1].strip()
                    if header=={}:
                        header={str(tmp[0]):str(tmp[1])}
                    else:
                        header[str(tmp[0])]=str(tmp[1])
                i+=1
        while i<len(fileLines):
            if fileLines[i].startswith('#'):
                i=i+1
            else:
                tmp=fileLines[i].split()
                for j in range(len(tmp)):
                    tmp[j]=tmp[j].strip()
                data.append(tmp)
                i+=1
        tmp=[]
        tmp1=[]
        for j in range(len(data)):
            for k in range(len(data[j])):
                tmp1=data[j][k].strip()
                if tmp1 !='':
                    tmp.append(tmp1)
            data[j]=tmp
            tmp=[]
        tmp=[]

        for j in range(len(cols)):
            for k in range(len(data)):
                try:
                    a=float(data[k][j])
                    tmp.append(a)
                except ValueError:
                    tmp.append(data[k][j])
                #else:
                 #   tmp.append(float(data[k][j])) # previously tmp.append(float(data[k][j]))
            tmp=array(tmp)

            if j == 0:
                dataCols={cols[j]:tmp}
            else:
                dataCols[cols[j]]=tmp
            tmp=[]

        return header,dataCols
Private method that reads in the header and column data.