使用 Python 解析文本：非结构化但具有不同格式的相似信息

Question

我正在尝试使用 Python 解析数千个包含公司、材料、化学特性等（具体来说是材料安全数据表）的规格表文本文件。文本文件包含结构松散格式的类似信息，以便人类可读，但结构不够结构化，不易解析（例如不是 XML 或 CSV）。简而言之，到处都是。

最初，数据是由不同公司的不同人员手工输入的。另一组人将信息转录到这些文本文件中（将其 OCR 转换为 txt 文件）。

是否有解析库或模式来提取这种类型的信息位？ （这似乎是一个“常见”的数据输入问题。）当然正则表达式会被大量使用。我对自然语言处理库没有任何经验。它们是否适合解决这个问题？

我最初的想法是尝试将文件分组到不同的类别中，然后为每种格式创建一组解析函数。不幸的是，他可能只适用于问题的一小部分，并且不同的情况可能很快就会失控。

由于这个问题很普遍，我将提供一堆示例来说明该问题。

地址信息
每个文件都包含公司信息，例如信息和地址。该信息可能有标识符，也可能没有，它可能在一行，也可能不在一行，等等。简而言之，似乎有每一种组合。

例如（带字段信息）：

MANUFACTURER: Foo Bar Inc.  
ADDRESS: 123 Foo St.  
Bar, CA 90012

例如。 （无/字段信息）：

Foo Bar Inc.  
123 Foo St.  
Bar, CA 90012

例如。 （有时信息之间有额外的行）：

FOO BAR INC.

123 FOO ST.

BAR, CA 90012

例如。 （字段名称不一致）：

MANUFACTURER'S NAME: FOO BAR INC.  
CREATIVE DIVISION  
ADDRESS: 123 FOO ST.  
CITY, STATE & ZIP: BAR, CALIFORNIA 90012  
PHONE NUMBER: 310-111-2222

SECTION INFO
规格表也有类似的部分，但顺序、标题、数字类型和分隔符不一致。

例如：

========================================
SECTION 1 -- MATERIALS
========================================

Ex：

Section I. Materials
------------------------------------------

Ex：

----- Section 3       Materials

有时文件的宽度发生了变化，因此以下换行符。

Ex：

===================================================
1.    Materials
===================================================

变成：

=========================================
==========
1.    Materials
=========================================
==========

这是一个完整的示例：
希望这能澄清解析文件的问题。您会注意到换行、信息分割在不同的行上等。并非所有内容都具有精确的结构，有些格式会有所不同，信息位于不同的位置。以下是纸质硬拷贝的链接。

MATERIAL SAFETY DATA SHEET

=================================================================
=========
SECTION I-PRODUCT AND PREPARATION INFORMATION
=================================================================
=========

MANUFACTURER:         Some Company Inc     EMERGENCY AND
INFORMATION
TELEPHONE
(111)222-3333
ADDRESS:              Some Road
City, ST
12346

IDENTITY (AS USED ON
LABEL AND LIST):      Some Identity

PREPARATION DATE:     Some Date

=================================================================
=========
SECTION II-HAZARDOUS INGREDIENTS/IDENTITY INFORMATION
=================================================================
=========

OSHA
ACGIH
HAZARDOUS COMPONENTS             CAS#       PEL   TWA        TLV
%
(SPECIFIC CHEMICAL IDENTITY;
COMMON NAME(S)
-----------------------------------------------------------------
---------

Some Chemical             111-22-3   15    10         10
12.34


=================================================================
=========
SECTION III-PHYSICAL/CHEMICAL CHARACTERISTICS
=================================================================
=========

Boiling Point:              N/A  Specific Gravity (H20=1):   N/A
Vapor Pressure (mm Hg):     N/A  Melting Point:              N/A
Vapor Density (AIR=1)       N/A  Evaporation Rate
(Butyl Acetate=1)           N/A
Solubility in Water:        None

Appearance:  Solid, various colors, may have slight
odor.

N/A = Not applicable

=================================================================
=========
SECTION IV-FIRE AND EXPLOSION HAZARD DATA
=================================================================
=========

FLASH POINT (METHOD USED):  None
FLAMMABLE LIMITS:  None          LEL:  N/A        UEL:  N/A
EXTINGUISHING MEDIA:  None
SPECIAL FIRE FIGHTING PROCEDURES:  None required.
UNUSUAL FIRE AND EXPLOSION HAZARDS:  None.

=================================================================
=========
SECTION V-REACTIVITY DATA
=================================================================
=========

STABILITY:  Stable
CONDITIONS TO AVOID:  None
INCOMPATIBILITY (MATERIALS TO AVOID):  None
HAZARDOUS POLYMERIZATION:  Will not occur

=================================================================
=========
SECTION VI-HEALTH HAZARD DATA
=================================================================
=========

ROUTES OF ENTRY:

INHALATION:  Yes
SKIN:  Possibly
INGESTION:  Possibly
EYES:  Possibly

HEALTH HAZARDS (ACUTE AND CHRONIC):  Pneumoconiosis, silicosis,
emphysema,
nose and throat irritation, eye irritation, skin irritation in
some.

CARCINOGENICITY:  No applicable information found.

SIGNS AND SYMPTOMS OF EXPOSURE:  Coughing, sneezing; irritation
of the
mucous membranes; eye irritation; skin irritation or rash, dry
throat.

MEDICAL CONDITIONS GENERALLY AGGRAVATED BY EXPOSURE:  Nasal,
bronchial or
pulmonary conditions which tend to restrict breathing, skin
abrasions.

EMERGENCY AND FIRST AID PROCEDURES:  Remove to fresh air,
irrigate eyes,
wash with soap and water, contact physician if necessary.

=================================================================
=========
SECTION VII-PRECAUTIONS FOR SAFE HANDLING AND USE
=================================================================
=========

STEPS TO BE TAKEN IN CASE MATERIAL IS RELEASED OR SPILLED:
Normal clean-up
procedures.

WASTE DISPOSAL METHOD:  Standard landfill methods consistent with
applicable state and federal regulations.

PRECAUTIONS TO BE TAKEN IN HANDLING AND STORING:  Use caution not
to drop,
crush, break or chip.

OTHER PRECAUTIONS:  Do not use at speeds greater than the
not-to-exceed
speed printed on the hub assembly.

=================================================================
=========
SECTION VIII-CONTROL MEASURES
=================================================================
=========

RESPIRATORY PROTECTION (SPECIFY TYPE):  OSHA or NIOSH approved
respirators
may be required.

VENTILATION:  Local exhaust recommended.  Special:  N/A.
Mechanical:  Useful.  Other:  N/A.

PROTECTIVE GLOVES:  May be useful.

EYE PROTECTION:  Recommended.

OTHER PROTECTIVE CLOTHING OR EQUIPMENT:  Not required.

WORK/HYGIENIC PRACTICES:  Keep clothing and area clean.  Wash to
remove

Answer 1

我会编写一个包含大量状态变量的 for 循环，处理每一行，并使用状态变量来跟踪正在发生的情况。 for 循环内的条件 (if) 会提出与人类手动解析文件时必须做的相同的“问题”。

"
for line in file:
    Is there a colon in line?
        field_name = normalize(informaton before the colon)
        data = information after the colon
    else: 
        field_name = next_field_in_list(previous_field)
        data = line
"

等等。
我无法从示例中理解您是否至少对字段有固定的顺序，
以及每个记录的最大字段数或不同的记录分隔符。如果没有这些，我想写起来会比较困难。