GeoCSV: Unterschied zwischen den Versionen
Aus Geoinformation HSR
Stefan (Diskussion | Beiträge) K |
Stefan (Diskussion | Beiträge) K |
||
Zeile 1: | Zeile 1: | ||
− | Specification of the tabular file format [[CSV]] (Comma Separated Values) with a geometry extension! | + | Specification of the tabular file format [[CSV]] (Comma Separated Values) with a geometry extension! ''(For notes and discussion see [[Diskussion:GeoCSV]])'' |
=== CSV file format specification === | === CSV file format specification === |
Version vom 1. Mai 2015, 13:23 Uhr
Specification of the tabular file format CSV (Comma Separated Values) with a geometry extension! (For notes and discussion see Diskussion:GeoCSV)
Inhaltsverzeichnis
CSV file format specification
About the content:
- First row contains attribute names separated by a => delimiter.
- Following rows are contains values separated by a => delimiter.
- Delimiter is semicolon (;) by default.
- Strings are enclosed by parantheses, to allow delimiters inside (e.g. "string").
- Data types (if supported from source or target system): See CSVT file format specification.
- All rows have same number of attributes.
- Calculations are possible in fields of type String (like "=A1+B1")
About file extensions, encoding and compression:
- Proposed file extension is .CSV (or .csv).
- Compression in format .ZIP (or .zip) is also possible and encouraged.
- Encoding is UTF-8 by default.
- End-of-lines are: CR, LF or CR/LF.
- Line Breaks in (String) fields are disallowed.
GeoCSV file format specification
GeoCSV is based on CSV. The extension comes with two variants: Options easting/northing and Options WKT.
Option "easting/northing" (longitude/latitude, similar to x/y in mathematics):
- Geometry Point type as two neighboring columns of type Float: one containing the easting coordinate, and one containing northing coordinate separated by the common delimiter.
- Example for the two easting/northing columnts "8.8249;47.2274".
- This option supports only Points.
Option WKT:
- It' one single column of type String containing a constructor, like for example: "POINT (8.8249 47.2274)".
- This option supports Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon.
- WKT ("Well Known Text") is originally defined by the Open Geospatial Consortium (OGC) and described in their Simple Feature Access specification (also ISO SQL/MM). See e.g. http://en.wikipedia.org/wiki/Well-known_text
Common restrictions:
- Coordinate system is WGS84 (EPSG:4326) by default.
- There is only one geometry column allowed per sheet.
- All geometry values within one table are in the same coordinate reference system (CRS).
CSVT file format specification
Field/column types, case insensitive (if supported from source or target system):
- Integer
- Real
- String
- Date ("YYYY-MM-DD"), Time ("HH:MM:SS+nn") and DateTime (YYYY-MM-DD HH:MM:SS+nn)
- (Lon/Lat)
- (WKT)
Notes:
- The geometry types are a kind of subtype: easting and northing values are stored as float, option WKT is stored in one column of type String.
- See also http://www.gdal.org/drv_csv.html section with .csvt extension.
Software
- Desktop
- Online:
- GeoConverter
- CSV-to-GeoJSON: convertcsv.com, csv2geojson
- GeoJSON-to-CSV: convertcsv.com
Examples
CSV type file 'example1.csvt':
Integer;String,Real,String,WKT
CSV file 'example1.csv:
id;name;amount;remarks;geom 1;Kevin;2.1;Rapperswil;point(8.8249 47.2274) 2;Eva;2.2;Zürich;point(8.5435 47.3768) 3;"Jimmy;Muff";2.3;Berne;point(7.4397 46.9487)
...can be shown as following table:
id | name | amount | remarks | geom |
---|---|---|---|---|
1 | Kevin | 2.1 | Rapperswil | POINT(8.8249 47.2274) |
2 | Eva | 2.2 | Zürich | POINT(8.5435 47.3768) |
2 | Jimmy;Muff | 2.3 | POINT(7.4397 46.9487) |
Note the remarks string in row 2 and the empty string in row 3.