Wednesday, April 22, 2015

LMSTFY ( Let Me That For You)

I should have mentioned this long ago before you invested time in reading my blog, but here goes... Fact is I'm not particularly bright, I'm just inquisitive (and as mentioned previously constructively lazy).  This means a couple of things; first I love to find an easier way to do almost anything, and second sometimes I spend more time researching than I would if I had just done the task (oh but next time it will be so much faster). Because of this, sometimes I know things, and when you know things people like to ask you things because you might know that particular thing they want.  Yes almost daily I am tempted to just say "Let me Google that for you" because that would be much easier for me than actually explaining it (reference lazy thing above).

I have about 150 out of the 240 layer numbers that I use daily in mapping projects memorized.  Over time though you need to add new layers or break them down to a more granular level so consequently you can see that there are a bunch I don't know.  I could memorize them (and a few I will) but the majority of the others I just want an easy way to find the rare one I need.  Hence or "Search Layer Names".

print ' modified 7:31 AM 4/16/2015'
# Display layers matching search string
Copyright 2015 Dennis Shimer
Vr Mapping copyright Cardinal Systems, LLC
No warranties as to safety or usability expressed or implied.
Free to use, copy, modify, distribute with author credit.

Prompts user for layer name (or any part) then displays layer
numbers and full names of layers matching string.

def lines2lists(AListOfDataLines):
    Function readlines returns an entire file with each line as a string in a
    list of data.  This function will convert each string into a list of words,
    then return a list of lists. Why? Just because I like to work this way.
    Example:            lines2lists(['first line','the second line','or sentences'])
    Would return:       [['first','line'],['the','second','line'],['or','sentences]]
    for Line in AListOfDataLines:
    return DataList


#If sent argument use as search string else prompt.
if VrArgs:
    SearchText=PyVrGui().InputDialog ('Search String', 'Layer numbers by name')[1]
LayerFileName = VrCfg().GetLayerNameFile ()
LayerFile = open(LayerFileName , 'r')
LayerData = LayerFile.readlines()
LayerList = man.lines2lists(LayerData)

#Search through data, if string found add it to a multi-line printable string.
for DataLine in LayerList :
    if len(DataLine) > 1 :
        if DataLine[1].count(SearchText.upper()):
            PrintString=PrintString+DataLine[0]+' '+DataLine[1]+'\n'
            PrintList.append(DataLine[0]+' '+DataLine[1])

# Two possibilities, the first commented line just displays the found layers
# The rest will let the user select one correct entry and send a LAY= command.
if PrintString:
#    PyVrGui().MsgBox(PrintString , 'Matching Layers')
    PromBox = VrPromBox ("Set Layer", 30, 1)
    PromBox.AddList ("Layer", 40, len(PrintList)+1, 0)
    for LayerItem in PrintList:
        PromBox.AddListItem (LayerItem)
    if (PromBox.Display(0) == 0):
        SetToLayer= PromBox.GetListByPrompt ("Layer")
    if SetToLayer : PyVrGui().PushKeyin('lay={:s}'.format( SetToLayer.split()[0]))
else :
    PyVrGui().MsgBox('No Match to {:s}'.format(SearchText), 'Matching Layers')

Wednesday, April 01, 2015

You gotta love a good library

The Columbus Metropolitan Library is arguably one of the best libraries in the nation.  I use it so much I have had my library card memorized for over 25 years.  The idea that there is information and services there at my fingertips any time I want is fantastic.  I was thinking about this yesterday when I started pulling functions out of PyVrGeom().  Libraries (modules) can be everything from little bits of code snippets that you want to reuse over and over to complex collections of classes that you could only dream up but never realistically code yourself. 

For example PyVrGeom is just a collection of math that some would find easy enough to code, but why do so when somebody has done the heavy lifting and offers you the calls to do it with some preexisting code.  In this case very professionally created and presented, but it is just as easy to hack together some snippets that just save you typing.  For example when I was working on a KML export routine I didn't need to learn something complex and universal (which libs probably exist), I just knew what it looked like and wanted to replicate those entities by passing along a few basic parameters.  In this case I slapped together some code to create the KML entities, but at the same time the coordinates needed to be in geodetic coordinates so I had to grab a projection library that someone way sharper than me had already put together. Then it struck me that a KMZ is just a file zipped using the standard algorithms so if I import that one I can just as easily write both KML and KMZ files.

I'm not going to offer any code this time just another reminder that there are some good reasons to install python if you are going to do some scripting.  Here are some of the libraries that I really enjoy and use often.

pyproj - for converting local coordinates to global (or from one to another).
liblas - for all things LiDAR related.
zipfile - for reading and writing compressed files.
xlrd/xlwt - for directly reading and writing Excel spreadsheets.

Along with some of the standard system libraries that you can find a million uses for like sys, os, time, and math.

And here is a tip I'll add for free, check out

For anyone interested in trying VrPython for the first time or if you are early in the game, I suggest going to the earliest posts and working forward. I use VrPython every day for many wonderful things, needless to say it will change and could potentially damage a file. Any risk associated with using VrPython or any code or scripts mentioned here lies solely with the end user.

The "Personal VrPython page" in the link section will contain many code examples and an organized table of contents to this blog in a fairly un-attractive (for now) form.