Python：如何在讀取.txt時使用tkinter繪製座標

Question

初次使用者。我是喬治梅森大學的一名研究生，我受到了很大的幫助，並且受到了社區的印象，所以我想我會提出一個問題。我想繪製使用tkinter從文本文件中指定的點（點在代碼的頂部指定，但我把它們放在一個文本文件中）。我的任務需要我來投射點，但我想更進一步，讓他們直接從我的變量中讀取，所以如果.txt改變，他們也會改變。我的問題是，我不知道如何解析變量，以便tkinter可以看到它們。

Here is the code: 

""" 
Read the following data (I put them into .txt first): 
Polyline; 
1: 1603714.835939442,142625.48838266544; 1603749.4678153452,142620.21243656706; 1603780.3769339535,142607.37201781105; 1603801.475846678,142582.27024446055; 1603830.4767344964,142536.14692804776; 
2: 1602514.2066492266,142330.66992144473; 1602521.4127475217,142414.92978276964; 1602520.1146955898,142433.93817959353; 1602501.3840010355,142439.12358761206; 1602371.6780588734,142417.84858870413; 1602351.6610373354,142408.02716448065; 1602334.5180692307,142388.58748627454; 1602331.6999511716,142376.66073128115; 1602334.8067251327,142348.965322732; 1602338.308919772,142323.6111663878; 1602349.0226452332,142314.50124930218; 1602363.9090971674,142310.79584660195; 1602514.2066492266,142330.66992144473; 

The following code define a function 'readPolylineFile' to read out data one line by one line 
The readPolylineFile function will return two polylines 

In addtion, try....except...finally are used to catch the exceptions 
""" 
import math 
class Points: 
    def __init__(self, x=0.0, y=0.0): 
     self.x,self.y = x, y 
class Polyline: 
    def __init__(self, points =[]): 
     self.points = points 
    def getLength(self): 
     i = 0 
     length = 0.0 
     while i < len(self.points)-1: 
      length += math.sqrt((self.points[i+1].x -self.points[i].x)**2 + (self.points[i+1].y -self.points[i].y)**2) 
      i += 1 
     return length 

## function to read out data one line by one line 
## return polylines list 
def readPolylineFile(fileName): 
    ## Declare variables that will be used outside of try blocks 
    polylines = [] ## empty polyline list to keep all polylines 
    f = None # empty file object 
    try:  
     f = open(fileName, 'r') ## Open the file and assign the return object to f  
     firstPolyLineNum = 0 
     index = 0 
     for line in f: 
      index += 1 
      if index == 1: ## Pass the first line 
       continue  
      coords = line.split(':')[1]    
      eachcoords = coords.split(';')   
      coordsLen = len(eachcoords) 
      points = [] ## Declare a points list to keep the points for each polyline 
      for i in range(coordsLen-1): 
       singlecoords = eachcoords[i] 
       xCoord = singlecoords.split(',')[0] 
       yCoord = singlecoords.split(',')[1] 
       print singlecoords 
       try: 
        point = Points(float(xCoord),float(yCoord)) 
        points.append(point) 

       except ValueError: 
        print 'Can not convert non-number to float' 
       except TypeError: 
        print 'Object type can not conver to float' 
      ## Create a polyline object based on the points 
      polyline = Polyline(points) 
      polylines.append(polyline) 

    except IOError: ##File does not exist 
     print 'IO Error while opening or reading the file' 
    finally: 
     if f: ## If file object exist, close the file 
      print 'Input .txt has been read and is now closed......' 
      f.close() 

    return polylines ## Return the polylines 


polylines = readPolylineFile('F://GMU Fall 2013/GGS 650/HW6/input.txt') 

try: 
    ## Get the first polyline 
    polyLine1 = polylines[0] 
    lengthForFirstPoly = polyLine1.getLength() 
    print "length for first polyline (first 5 coordinates) -> ", lengthForFirstPoly 

    ## Gets the points for second polyline 
    polyLine2 = polylines[1] 
    lengthForSecondPoly = polyLine2.getLength() 
    print "length for Second polyline (last 13 coordinates) -> ", lengthForSecondPoly 

except: 
    print "error in processing polyline objects created" 

from Tkinter import * 

master = Tk() 
master2 = Tk() 

w = Canvas(master, width=800, height=600) 
w.pack() 
w.create_line(0, 0, 200, 100) 

w = Canvas(master2, width=800, height=600) 
w.pack() 
w.create_line(0, 0, 200, 297) 
mainloop() 

Answer 1

所有你需要做的是建立在折線的方法返回所有它的點作爲一個平面列表中的座標，然後用它來創建行。

這裏的返回座標的扁平列表的快速和骯髒的例子：

class Polyline(self): 
    ... 
    def getCoordinates(self): 
     coords = [] 
     for point in self.points: 
      coords.append(point.x) 
      coords.append(point.y) 
     return coords 

下面介紹如何在畫布上創建一個線，用於對摺線：

for polyline in polylines: 
    canvas.create_line(polyline.getCoordinates())