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Best practice about species data

Page history last edited by yichuan.shi 12 years, 1 month ago

1.     Digitizing shotcuts

It could speed up the process by not having to switch to different zoom/pan commands and come back to edit command. Most commonly used: z for zoom-in, x for zoom-out, c for pan


2.     Digitizing using geodatabase templates (added benefits)

Geodatabase template helps you fill in default values and supports domains which limit values that could be filled in for specified fields, thus reducing errors of typo and repetitive attribute fillings.


3.     Digitizing tricks: copy and paste, trace, clip, intersect (do it when digitizing or leave it later for batching)

In cases where you want to copy exactly the same geometry/shape, you can simply make the layer, which you want to select geometry from, the only selectable layer. Select the geometry you want, press Ctrl- C and immediately Ctrl-V afterwards.


4.     Extracting freshwater catchments using graphics for species distribution

Selecting catchments by various manual selection tools could be inefficient, slow and sometimes problematic. Imagine a situation when you need to select basins according to a paper map, if the range is widespread, you might have to use ‘Interactive Selection Method/Add to current selection tool’. It could be slow for the system to draw and adding/deleting sporadic catchments may not be efficient. You can try ‘Draw/polygon’, and then choose ‘Select By Graphics’. You’ll spot the difference


5.     Names (avoid typos, copy and paste errors)

When editing attribute tables, it would be easier and less likely to make mistakes if you copy and paste than typing manually. However, copy and paste may become ‘dangerous’ if ‘invisible’ strings such as tab or end-of-line, is also copied over. Take Excel for example, if you select a cell and click copy. You essentially copy the entire string plus the invisible ‘next line character’ over to a cell in the attribute table. Although they look the same, they are different. Solution: use a pure text file for copy and paste or highlight the string, right click ,choose copy and then paste.


6.     Join table versus selection by attributes

Personally I would recommend you use ‘select by attributes’ when trying to identify corresponding rows by a list. Joining table should in theory do exactly the same as the SQL way aforementioned, however, in practice, especially when non ESRI native tables are used, the join can be sometimes incomplete and result in empty joined tables. The most common reason is formatting. Convert to a pure text format! (.txt or .csv)


7.     Naming conventions

Make sure NO WHITE SPACE in folder names or files names. Some programs will not work properly if it encounters these white spaces. It is one of many common causes for python scripts to fail.


8.     Single quote issue

Single quote in species name (sub species) must be replaced with two single quotes to facilitate SQL query. It is one of many common causes for scripts to fail.


9.     European accent

Encodings can be quite tricky and different systems handle them differently. No accent in the species name!  It is one of many common causes for scripts to fail, again…


10.  Native ESRI environment dealing with shapefile

Shapefiles, as we all know, can be easily corrupted and become unusable especially non-native programs are used in processing them, causing their behaviours to be unpredictable. Always choose native ESRI software in handling shapefiles whenever possible.


11.  Save map documents!

Map documents hold links to data, cartographic layouts and geoprocessing results. It is a very good idea to save your working map document whenever you do something to your data, thus providing a way of tracing back what happened.


12.  Result tab and search tab in ArcGIS 10

Very useful tabs. Result tab is also where you find background geoprocessing is running or not.


13.  Draft mode when tuning layouts

As is a common task for us, producing maps could be time consuming and getting the layout nice and pretty can be painful. This is especially true if each time some element on your layout needs to be repositioned but your entire data frame has to refresh. This can be easily solved by ticking the ‘draft mode’ box in the frame tab of the data frame property, preventing it from drawing:


14.  Make sure all spatial data have a correct spatial reference/ coordinate system

This prevents some not-so-easy-to-identify problems or unexpected result (e.g. calculating areas). It is always a good practice to make sure that all data have correct spatial references

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