soil_table_reader

Basic implementation of tabula-java to extract soil analysis table from PDFs. It allows the user to extract table data from PDFs in different formats, using templates and converting the result to JSON.

How to create Templates

Templates are JSON files that describes the table content, that is inside a PDF. Here you can find an example: https://github.com/Scicrop/soil_table_reader/blob/main/dist/template.json

Define table area

Tabula has the ability to detect tables, however you can define a region (a rectangle) where the table will appear. This is a good approach when in a single PDF page there are several tables and you want to extract only one. There are 4 parameters that you need to check in order to define the table area: Top, Left, Bottom, Right. In the image bellow you can understand how these parameter are placed:

List of all template parameters

{
	"columns": [	
			{"column": "analysis_code", "description": "Código da Análise", "type": "String", "unit":""},
			{"column": "sample", "description": "Amostra", "type": "String", "unit":""},
			{"column": "ph_1", "description": "pH H2O", "type": "Float", "unit":""},
			{"column": "ph_2", "description": "pH CaCl2", "type": "Float", "unit":""},
			{"column": "mo", "description": "M.O.", "type": "Integer", "unit":"g dm-3"},
			{"column": "p_mg", "description": "P", "type": "Float", "unit":"mg dm-3"},
			{"column": "k_plus_mg", "description": "K+", "type": "Integer", "unit":"mg dm-3"},
			{"column": "so4_3_minus_mg", "description": "SO4 2-", "type": "Integer", "unit":"mg dm-3"},
			{"column": "k_plus_cmol", "description": "K+", "type": "Float", "unit":"cmol c dm-3"},
			{"column": "ca2_plus_cmol", "description": "Ca2+", "type": "Float", "unit":"cmol c dm-3"},
			{"column": "mg2_plus_cmol", "description": "Mg2+", "type": "Float", "unit":"cmol c dm-3"},
			{"column": "ca_plus_mg_cmol", "description": "Ca+Mg", "type": "Float", "unit":"cmol c dm-3"},
			{"column": "al3_plus_cmol", "description": "Al3+", "type": "Float", "unit":"cmol c dm-3"},
			{"column": "h_plus_al_cmol", "description": "H+Al", "type": "Float", "unit":"cmol c dm-3"}
		   ],
	"options": {
				"discard_rows":[0,1], 
				"name":"Análise Química",
				"top": 100,
				"left": 30,
				"bottom": 300,
				"right": 500
				}
}

Implementation

Return a JSON String

String jsonOutputString = TableParser.getInstance().tableToJsonString("dist/template.json", "/tmp/laudo.pdf");

Return an Object

List<OutputRow> object = TableParser.getInstance().tableToObject("dist/template.json", "/tmp/laudo.pdf");

Results

Here you can see an example of just one row extracted from PDF table:

[
    {
        "column": "analysis_code",
        "description": "Código da Análise",
        "type": "String",
        "unit": "",
        "value": "Analysis-0001"
    },
    {
        "column": "sample",
        "description": "Amostra",
        "type": "String",
        "unit": "",
        "value": "Farm A 0-20"
    },
    {
        "column": "ph_1",
        "description": "pH H2O",
        "type": "Float",
        "unit": "",
        "value": 5.3
    },
    {
        "column": "ph_2",
        "description": "pH CaCl2",
        "type": "Float",
        "unit": "",
        "value": 4.7
    },
    {
        "column": "mo",
        "description": "M.O.",
        "type": "Integer",
        "unit": "g dm-3",
        "value": "28"
    },
    {
        "column": "p_mg",
        "description": "P",
        "type": "Float",
        "unit": "mg dm-3",
        "value": 0.71
    },
    {
        "column": "k_plus_mg",
        "description": "K+",
        "type": "Integer",
        "unit": "mg dm-3",
        "value": "64"
    },
    {
        "column": "so4_3_minus_mg",
        "description": "SO4 2-",
        "type": "Integer",
        "unit": "mg dm-3",
        "value": "6"
    },
    {
        "column": "k_plus_cmol",
        "description": "K+",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 0.17
    },
    {
        "column": "ca2_plus_cmol",
        "description": "Ca2+",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 1.21
    },
    {
        "column": "mg2_plus_cmol",
        "description": "Mg2+",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 0.51
    },
    {
        "column": "ca_plus_mg_cmol",
        "description": "Ca+Mg",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 1.73
    },
    {
        "column": "al3_plus_cmol",
        "description": "Al3+",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 0.25
    },
    {
        "column": "h_plus_al_cmol",
        "description": "H+Al",
        "type": "Float",
        "unit": "cmol c dm-3",
        "value": 5.32
    }
]