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python-3.x - 读取具有不同长度标头的数据

问题描述

我想在 python 中读取一个包含可变长度标头的文件，然后在数据帧/系列中提取标头之后的变量。
数据看起来像：

....................................................................
Data coverage and measurement duty cycle:
When the instrument duty cycle is not in measure mode (i.e. in-flight     
calibrations) the data is not given here (error flag = 2). 

The measurements have been found to exhibit a strong sensitivity to cabin 
pressure.
Consequently the instrument requires calibrated at each new cabin    
pressure/altitude.

Data taken at cabin pressures for which no calibration was performed is    
not given here (error flag = 2).
Measurement sensivity to large roll angles was also observed.
Data corresponding to roll angles greater than 10 degrees is not given    
here (error flag = 2)
......................................................................
High Std: TBD ppb
Target Std: TBD ppb
Zero Std: 0 ppb

Mole fraction error flag description :
0 : Valid data
2 : Missing data
31636 0.69 0
31637 0.66 0
31638 0.62 0
31639 0.64 0
31640 0.71 0
.....
.....

所以我想要的是将数据提取为：

    Time    C2H6  Flag
0  31636  0.69 0   NaN
1  31637  0.66 0   NaN
2  31638  0.62 0   NaN
3  31639  0.64 0   NaN
4  31640  0.71 0   NaN
5  31641  0.79 0   NaN
6  31642  0.85 0   NaN
7  31643  0.81 0   NaN
8  31644  0.79 0   NaN
9  31645  0.85 0   NaN

我可以做到这一点

infile="/nfs/potts.jasmin-north/scratch/earic/AEOG/data/mantildas_faam_20180911_r1_c118.na"
flightdata = pd.read_fwf(infile, skiprows=53, header=None, names=['Time', 'C2H6', 'Flag'],)

但我跳过了大约 53 行，因为我计算了我应该跳过多少。我有一堆这些文件，有些在标题中没有正好 53 行，所以我想知道处理这个问题的最佳方法是什么，以及让 Python 在找到它们时始终只读取三列数据的标准? 我想如果我想要让我们说 Python 实际从遇到的地方读取数据

Mole fraction error flag description :
0 : Valid data
2 : Missing data

我应该怎么办 ？使用另一个更好的标准呢？

标签： python-3.xpandasheaderformattingcontent-length

解决方案

您可以拆分标题分隔符，如下所示：

with open(filename, 'r') as f:
    myfile = f.read()
infile = myfile.split('Mole fraction error flag description :')[-1]
# skip lines with missing data
infile = infile.split('\n')
# likely a better indicator of a line with incorrect format, you know the data better
infile = '\n'.join([line for line in infile if ' : ' not in line])
# create dataframe
flightdata = pd.read_fwf(infile, header=None, names=['Time', 'C2H6', 'Flag'],)

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