Latest Contributions by WilliamCole

Understanding Python dict Statement:   I am new to Python, so forgive me if I’m asking questions about what should be obvious. If this is posted in the wrong place, my apologies: please let me know where I should be posting this.   Using Python 2.7.   I am re-using and modifying 2014 code that was written by Martjin Pieters and posted to StackOverflow [message 5268929]. It allows for the comparison of two CSV files, reporting on the differences between the master and host files. I thank him for this head start. I am comparing a file exported from ArcGIS using ArcPy. Here it is:   1 #2/3/2021 2 #Source: Stack Overflow "Compare two CSV files and search for similar items” 3 4 import csv 5 6 with open('masterlist.csv', 'rb') as master: 7 master_indicies = dics ((r[1], i) for i, r in enumerate(csv.reader(master))) 8 9 with open('hosts.csv', 'rb') as hosts: 10 with open('results.csv', 'wb') as results: 11 reader = csv.reader(hosts) 12 writer = csv.writer(results) 13 14 for row in reader: 15 index = master_indices.get(row[3]) 16 if index is not None: 17 message = 'FOUND in master list (row {})' .format(index) 18 else: 19 message = 'NOT FOUND in master list' 20 writer.writerrow(row + [message])   I sort of understand most of it save one section of line 7 shown in the figure below (though not sure I’ve parsed [the colors] the components correctly):       The part highlighted in green is the one element of the dict entry I simply do not know how to read/interpret [what is ‘r’?; what is ‘i’ and what does ‘i) for i’ do; etc.]. If someone could point me to a place that I could learn about dict at an introductory level, hopefully with enough specificity that would help me to sort this out; that would be great. Just trying to get my head around this.   Thank you very much. ... View more

I am looking for a hydrology tutorial for ArcGIS Desktop 10.8.x.   I have used the Hydrologic analysis sample applications for ArcMap web page as a start, but find that there are missing pieces - parts that I don't understand - that I have not been able to sort out.  I was hoping to find a tutorial like the excellent ArcGIS Spatial Analysis Extension Tutorial.  Suggestions would be gratefully received. Thank you all very much, Bill Cole ... View more