Tim Evans Computing Page

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Web Tips

To put an icon on a web page, first make a 16x16 pixel Windows icon file, e.g. IrfanView will take most formats and then can resize to the correct size and finally save in the required format. Then in the head section of the html code, usually before the body section, insert the link code e.g.

Take a look at the source of this page to see this.

Excel

To count number of times in a column subject to a condition based on a number on another cell use something like
```
=countif(B2:B20,"="&A10)
```
which will count the number of times the value in cell 10 appears in the cells B2 to B20. Note the use of quotes round most of the condition (normally all goes in quotes) while the cell reference in the condition is preceded by the ampersand.

GIS

Useful programmes

The most important thing I learnt is that proper GIS programmes keep data in layers. Each layer can only have one type of object: points, lines or polygons. However some formats such as KML can have more than one type of object in the same file. So when trying to import/export, you may need to split files up or join files together, working by type of object.from such

Quantum GISGUI front end for GRASS. Flakey but open source. Very powerful when it works, with lots of add ons. Currently the one I try first. See below for further tips.

MapWindowNo vector output but very useable. Google Earth and its simple KML language. I produce output in this format as it is a simple XML type format, easy to produce in my code (I have some hand written XML code for other formats which I started from) and is often read by other files (but see comments below). GPSBabel Free (donation requested) software which converts between endless formats e.g. KML to GPX. kmltogpx KML to GPX converter MapInfo Used by Soren. EasyGPS ArchGIS GRASS open source but difficult to use. GeoConverter is an online front-end for ogr2ogr D2M - an online conversion utility from Data2Map zonums is a web site full of useful conversion routines, both online and downloadable.

QGIS QGIS (Quntum GIS) is GUI but based on GRASS. Lots of add ons but not always perfect. I found the plugin "Add Delimited Text Layer" most useful for reading in a spreadsheet of data on points. KML files must be split up into parts with just one type of element (just points, or just lines, etc) when using the KML import. Use the ABC "Labeling" button to add labels. Seems to do so in an intelligent (non overlapping way, set priority high). In principle some of the buttons near this one allow you to edit label positions too but you seem to have to add positions to the labels in the "Data defined settings" sections of the "Labeling" screen. Note also that clicking on properties of the point layer brings up what seems to be an old fashioned approach to labelling that is not intelligent. I found the export options limited. For vector output the svg did not work for me. PDF looks OK but I can not edit it. I installed a Windows printer driver (from HP) and used it to print to a file, and that seemed to produce a postscript file. Viewing in ghostscript then allowed me to save as an eps. This seems OK and . Importing KML into other GIS programmes Free Geography Tools suggests using a KML to GPX conversion. To convert a KML file to a GPX file use GPSBabel. Choose Google Earth (Keyhole) Markup Language as the input filetype, and select the KML file. Then select GPX as the Output file type, specify the filename and location. Click let's go. Could also try kmltogpx. The zonums web site has an online KML to CSV and other formats converter which worked well with a list of points that I tried. Another trick is to rename a KML file as .xml and then use Excel or similar to open it. Hand editing of the spread sheet is relatively simple. The key thing to remember is that KML puts both points and lines in the same file. When importing a KML file into a GIS programme I have found that some will only pick up one type (I had may file giving points then lines and it only got the points). However shape files work with each layer being one type of object (points, layers, polygons) and each layer is a separate shape file.