Python write() 函数将先前的数据写入下一个文件

Question

我正在从文本文件中读取文本，然后重新格式化该文本以写入不同的文本文件。

我正在阅读的文本如下:testFile.txt:

                  *******************************
                  *  Void Fractions in the Bed  *
                  *******************************

     Z(m)    MIN.FLUIDIZ.  EMULSION    TOTAL

0.0000E+00  0.4151E+00  0.8233E+00  0.8233E+00
0.1000E-09  0.4151E+00  0.8233E+00  0.8233E+00
0.1000E-05  0.4151E+00  0.8233E+00  0.8233E+00
0.2000E-05  0.4151E+00  0.8233E+00  0.8233E+00
0.1251E+01  0.4151E+00  0.9152E+00  0.9152E+00
0.1301E+01  0.4151E+00  0.9152E+00  0.9152E+00
0.1333E+01  0.4151E+00  0.9152E+00  0.9152E+00


               *************************************
               *  Void Fractions in the Freeboard  *
               *************************************

     Z(m)    VOID FRACTION

0.1333E+01  0.9992E+00
0.1333E+01  0.9992E+00
0.1333E+01  0.9992E+00
0.1333E+01  0.9992E+00
0.3533E+01  0.9992E+00
0.3633E+01  0.9992E+00
0.3733E+01  0.9992E+00
0.3833E+01  0.9992E+00
0.3933E+01  0.9992E+00
0.4000E+01  0.9992E+00


           *********************************************
           *  Superficial Velocities in the Bed (m/s)  *
           *********************************************

     Z(m)    MIN.FLUIDIZ.  ACTUAL

0.0000E+00  0.1235E+00  0.4911E+01
0.1000E-09  0.1235E+00  0.4911E+01
0.1000E-05  0.1235E+00  0.4911E+01
0.2000E-05  0.1235E+00  0.4911E+01
0.3000E-05  0.1235E+00  0.4911E+01
0.1151E+01  0.1235E+00  0.4915E+01
0.1201E+01  0.1235E+00  0.4915E+01
0.1251E+01  0.1235E+00  0.4915E+01
0.1301E+01  0.1235E+00  0.4915E+01
0.1333E+01  0.1235E+00  0.4915E+01

下面是我解析文本文件的 Python 代码:

openFile = open('testFile.txt','r')

groupOneFile = open('groupOneFile.csv','w')
groupTwoFile = open('groupTwoFile.csv','w')
groupThreeFile = open('groupThreeFile.csv','w')

idx = 0;
firstIdx = 0;
secondIdx = 0;
thirdIdx = 0;

for line in openFile:

    # first group
    if '*  Void Fractions in the Bed  *' in line:
        print line
        firstIdx = idx

    if idx in range(firstIdx+5,firstIdx+43):
        line = line.lstrip()
        line = line.replace('  ',',')
        groupOneFile.write(line)

    # second group
    if '*  Void Fractions in the Freeboard  *' in line:
        print line
        secondIdx = idx

    if idx in range(secondIdx+5,secondIdx+43):
        line = line.lstrip()
        line = line.replace('  ',',')
        groupTwoFile.write(line)        

    # third group
    if '*  Superficial Velocities in the Bed (m/s)  *' in line:
        print line
        thirdIdx = idx

    if idx in range(thirdIdx+5,thirdIdx+43):
        line = line.lstrip()
        line = line.replace('  ',',')
        groupThreeFile.write(line)

    idx += 1

openFile.close()

groupOneFile.close()
groupTwoFile.close()
groupThreeFile.close()

groupOneFile 中应包含以下数据:

0.0000E+00,0.4151E+00,0.8233E+00,0.8233E+00
0.1000E-09,0.4151E+00,0.8233E+00,0.8233E+00
0.1000E-05,0.4151E+00,0.8233E+00,0.8233E+00
0.2000E-05,0.4151E+00,0.8233E+00,0.8233E+00
0.1251E+01,0.4151E+00,0.9152E+00,0.9152E+00
0.1301E+01,0.4151E+00,0.9152E+00,0.9152E+00
0.1333E+01,0.4151E+00,0.9152E+00,0.9152E+00

groupTwoFile 应具有以下内容:

0.1333E+01,0.9992E+00
0.1333E+01,0.9992E+00
0.1333E+01,0.9992E+00
0.1333E+01,0.9992E+00
0.3533E+01,0.9992E+00
0.3633E+01,0.9992E+00
0.3733E+01,0.9992E+00
0.3833E+01,0.9992E+00
0.3933E+01,0.9992E+00
0.4000E+01,0.9992E+00

groupThreeFile 依此类推。

读取主文本文件并将数据写入其他文件工作正常。问题是写入 groupOneFile 的数据也被写入其他文件 groupTwoFile 和 groupThreeFile 的开头。如何防止这种情况发生？

Answer 1

要使其正常工作，您只需初始化即可

firstIdx = 1000000
secondIdx = 1000000
thirdIdx = 1000000

因为问题是如果你将它们设置为 0那么第一行将在所有组的范围内。

但请注意，这段代码效率非常低...更好的方法可能是:

outputFile = None

for line in openFile:
    if '*  Void Fractions in the Bed  *' in line:
        idx = 0; outputFile = groupOneFile
    elif '*  Void Fractions in the Freeboard  *' in line:
        idx = 0; outputFile = groupTwoFile
    elif '*  Superficial Velocities in the Bed (m/s)  *' in line:
        idx = 0; outputFile = groupThreeFile

    if outputFile and 5 <= idx < 43:
        line = line.lstrip()
        line = line.replace('  ',',')
        outputFile.write(line)

    idx = idx + 1

在 Python 中，如果你写 if x in range(a, b):每次进行测试时都会对每个元素进行检查(或者在 Python 2.x 中，构建从 a 到 b-1 的所有整数的实际列表)。更好的方法是将测试编写为 if a <= x < b: .

另请注意 2.5 in range(0, 10)会返回 false(当然 0 <= 2.5 < 10 是 true)。

在Python中没有switch语句，但您可以改为构建一个调度表:

filemap = [('*  Void Fractions in the Bed  *', groupOneFile),
           ('*  Void Fractions in the Freeboard  *', groupTwoFile),
           ('*  Superficial Velocities in the Bed (m/s)  *', groupThreeFile)]

outputFile = None
for line in openFile:
    for tag, file in filemap:
        if tag in line:
            idx = 0
            outputFile = file
    if outputFile and 5 <= idx < 43:
        outputFile.write(line)
    idx += 1

如果可以精确匹配(而不是 in 测试)，那么使用字典可以做得更好:

filemap = {'*  Void Fractions in the Bed  *': groupOneFile,
           '*  Void Fractions in the Freeboard  *': groupTwoFile,
           '*  Superficial Velocities in the Bed (m/s)  *': groupThreeFile)}

outputFile = None
for line in openFile:
    f = filemap.get(line.strip())
    if f:
        # Found a new group header, switch output file
        idx = 0
        outputFile = f
    if outputFile and 5 <= idx < 43:
        outputFile.write(line)
    idx += 1