Python 练习之画幅好画_reportlab lineplot

《python基础教程》画幅好画使用reportlab模块画出太阳黑子的曲线图。

源代码：

from reportlab.lib import colors  
from urllib import urlopen  
from reportlab.graphics.shapes import *  
from reportlab.graphics.charts.lineplots import LinePlot  
from reportlab.graphics import renderPDF  
  
URL="http://www.swpc.noaa.gov/ftpdir/weekly/Predict.txt"  
COMMENT_CHARS='#:'  
  
drawing = Drawing(400,200)  
data = []  
for  line in  urlopen(URL).readlines():  
    if not line.isspace() and not line[0] in COMMENT_CHARS:  
        data.append([float(n) for n in line.split()])  
  
pred = [row[2] for row in data]  
high = [row[3] for row in data]  
low = [row[4] for row in data]  
times = [row[0] + row[1]/12.0 for row in data]  
  
lp = LinePlot()  
lp.x = 50  
lp.y = 50  
lp.height = 125  
lp.width = 300  
lp.data = [zip(times,pred),zip(times,high),zip(times,low)]  
drawing.add(lp)  
  
renderPDF.drawToFile(drawing,'report.pdf','Sunspots')  

但是这个是基于python2， 但是很多开始使用python3。用python3运行这段代码的时会报 typeerror

TypeError: 'zip' object is not subscriptable

这是因为在python2 中zip函数返回的是list，python3 中zip函数返回的是迭代器。所以会出现上面的错误。

python3 的源代码：

from reportlab.lib import colors
from reportlab.graphics.shapes import *
from reportlab.graphics import renderPDF
from reportlab.graphics.charts.lineplots import LinePlot
from reportlab.graphics.charts.textlabels import Label
import re

file = open('Predict.txt','r')
drawing = Drawing(400,200)
data = []

for line in file.readlines():
    lineList = []
    if re.match('#',line):
        continue
    line = re.sub('\s+','%',line)
    lineList = line.split('%')
    data.append(lineList)

pred = [float(row[2]) for row in data]
high = [float(row[3]) for row in data]
low = [float(row[4]) for row in data]
time = [ float(row[0]) + float(row[1])/12.0 for row in data]

lp = LinePlot()
lp.x= 50
lp.y= 50
lp.height = 125
lp.width = 300
#通过list函数将zip的返回转化成list
lp.data = [list(zip(time,pred)),list(zip(time,high)),list(zip(time,low))]
lp.lines[0].strokeColor = colors.blue
lp.lines[1].strokeColor = colors.red
lp.lines[2].strokeColor = colors.green

drawing.add(lp)
drawing.add(String(250,150,'Sunspots',fontSize = 14, fillColor = colors.red))

renderPDF.drawToFile(drawing, 'report.pdf','Sunspots')