topic Re: Iterating through a dictionary in Python Questions

Iterating through a dictionary

JoeBorgione — Sat, 11 Dec 2021 19:48:33 GMT

I have a dictionary in the form of:

year2018 = {'jan18':(1,2018),'feb18':(2,2018),'mar18':(3,2018), 'apr18':(4,2018),
            'may18':(5,2018),'jun18':(6,2018),'jul18':(7,2018),'aug18':(8,2018),
            'sept18':(9,2018),'oct18':(10,2018),'nov18':(11,2018),'dec18':(12,2018)
            }‍‍‍‍

I have a data table where each record has Month field and a Year field. I would like to iterate through my dictionary so that while key = jan18, I select records from my table where Month = 1 and Year = 2018, and then export those records to a stand-alone table called jan18: then move on to key = feb18, etc etc. I've tried a couple different approaches, but still not quite getting what I want. Any suggestions are appreciated. (Using a dictionary is cool, but I'm open to all suggestions...)

Re: Iterating through a dictionary

Yuriko — Sat, 11 Dec 2021 19:48:35 GMT

Hi Joe, I'm not sure what you've attempted but dictionaries are indeed cool. I haven't tested this but give this a whirl:

for key, value in year2018.items(): # Iterate through each key,value pair in the dictionary
    in_features = in_feature_class # Identify the input feature class
    out_feature_class = out_path + "_" + key # Identify the filepath output appending the key to identify it
    where_clause = "Month = '" + str(value[0]) + "' AND Year = '" + str(value[1]) + "'"
    arcpy.Select_analysis(in_features, out_feature_class, where_clause)

Re: Iterating through a dictionary

JoeBorgione — Mon, 06 May 2019 22:44:33 GMT

Thanks- I'm working on a table, not a feature class so I don't think Select_Analysis() will work. However, If I make a table view first, and run my selections on it, this should give me what I'm after....

Re: Iterating through a dictionary

DanPatterson_Retired — Mon, 06 May 2019 22:59:48 GMT

you ruled out Split By Attributes—Help | ArcGIS Desktop ?

might require adding a temporary field to concatenate your month and year if your data aren't set up for a straight split as is

Re: Iterating through a dictionary

RandyBurton — Sat, 11 Dec 2021 19:48:38 GMT

You can iterate through a dictionary, but some simple loops are easy. Just ideas..

months = {1:'jan',2:'feb',3:'mar',4:'apr',5:'may',6:'jun',7:'jul',8:'aug',9:'sep',10:'oct',11:'nov',12:'dec'}
for yr in range(2018,2019): # stop when 2019 is reached
    for mo in months:
        print yr, mo, months[mo]
        print "Month = {} AND Year = {}".format(mo,yr)
        print "{}_{}".format(months[mo], yr)

''' prints:
2018 1 jan
Month = 1 AND Year = 2018
jan_2018
... etc.
'''
for yr in range(2018, 2019): # stop when 2019 is reached
    for mo in range(1,13): # stop when 2019 is reached
        print yr, mo

''' prints
2018 1
2018 2
...
2018 11
2018 12
'''‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

Re: Iterating through a dictionary

JoeBorgione — Tue, 07 May 2019 13:48:20 GMT

I've never used this tool before: it's my new favorite. It's fun to write python and do all sorts of elaborate gyrations, but hey, this is slick!

Re: Iterating through a dictionary

DanPatterson_Retired — Tue, 07 May 2019 13:57:13 GMT

Joe... 15 years ago or so...

Split Layer By Attribute

When it wasn't free. Mine still has the better Thumbnail

Re: Iterating through a dictionary

JoshuaBixby — Tue, 07 May 2019 16:12:42 GMT

Then use Table Select—Help | ArcGIS Desktop instead.