项目2：画幅好画

这个项目比较简单，介绍了ReportLab的用法。

首先要用到的是画折线类，PolyLine，用法很简单，看下面的例子：

from reportlab.lib import colors
from reportlab.graphics.shapes import*
from reportlab.graphics import renderPDF

drawing = Drawing(200, 150)
drawing.add(PolyLine([(50, 50), (100, 50), (100, 100), (50, 100), (50, 50)]))

renderPDF.drawToFile(drawing, 'report2.pdf', 'Sunsports')

from reportlab.lib import colors
from reportlab.graphics.shapes import*
from reportlab.graphics import renderPDF

data=[
        # Year  Month  Predicted  High  Low
        (2007, 8, 113.2, 114.2, 112.2),
        (2007, 9, 112.8, 115.8, 109.8),
        (2007, 10, 111.0, 116.0, 106.0),
        (2007, 11, 109.8, 116.8, 102.8),
        (2007, 12, 107.3, 115.3, 99.3),
        (2008, 1, 105.2, 114.2, 96.2),
        (2008, 2, 104.1, 114.1, 94.1),
        (2008, 3, 99.9, 110.9, 88.9),
        (2008, 4, 94.8, 106.8, 82.8),
        (2008, 5, 91.2, 104.2, 78.2)
     ]

drawing = Drawing(200, 150)

pred = [row[2]-40 for row in data]
high = [row[3]-40 for row in data]
low = [row[4]-40 for row in data]
times = [200*((row[0]+row[1]/12.0)-2007)-110 for row in data]

drawing.add(PolyLine(list(zip(times, pred)), strokeColor = colors.blue))
drawing.add(PolyLine(list(zip(times, high)), strokeColor = colors.red))
drawing.add(PolyLine(list(zip(times, low)), strokeColor = colors.green))
drawing.add(String(65, 115, 'Sunspots', fontSize=18, fillColor = colors.red))

renderPDF.drawToFile(drawing, 'report1.pdf', 'Sunsports')

 

这儿需要注意的一点是书上的写法是：

PolyLine(zip(times, pred), strokeColor = colors.blue)

但是在python3中这样写是错误的，会有 TypeError: object of type 'zip' has no len() 错误。可以改写成上述写法。

接下来是进阶版本，不难：

from urllib.request import urlopen   #python3中在request中
from reportlab.graphics.shapes import *
from reportlab.graphics.charts.lineplots import LinePlot
from reportlab.graphics.charts.textlabels import Label
from reportlab.graphics import renderPDF

URL = 'http://services.swpc.noaa.gov/text/predicted-sunspot-radio-flux.txt'
COMMENT_CHARS = '#:'

drawing = Drawing(400, 200)
data = []

for line in urlopen(URL).readlines():
    line = line.decode()  #这儿需要这样做，否则下面无法转化成float，具体不太清楚。。。
    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 = 120
lp.width = 300

lp.data =[tuple(zip(times, pred)), tuple(zip(times, high)), tuple(zip(times, low))]  #这儿最后也要转换成元组

lp.lines[0].strokeColor = colors.red
lp.lines[1].strokeColor = colors.blue
lp.lines[2].strokeColor = colors.green

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

renderPDF.drawToFile(drawing, 'report2.pdf', 'Sunspots')