Thematic mapping in ArcGIS Desktop

hi let's say you want to have full control over your data you want to choose how to classify it in what ways to classify it how many classes to create from your data you want to be able to have full control over whether you want a dot map or a pie chart map or a choropleth color-coded map or a graduated symbol map in short you want to be able to have full control over how your data is displayed so you have a maximum power possible in which to analyze it well then what you want to do is to bring that data into ArcGIS desktop ArcGIS desktop allows you to have full control over your data you'll be able to classify it symbolize it and analyze it using a variety hundreds of spatial tools at your fingertips you'll also be able to analyze the attribute data that's the eye part of GIS the database behind your maps let's talk about and demonstrate how to do that okay let's get started here I have a new session of arcmap arcmap is an application inside arcgis desktop i'm going to add some data with the plus sign how about some historical data by state I'm going to add States rivers highways federal land and cities how about Canada and Mexico as well great there's my data now I'm going to symbolize that data first of all any one of these layers can be turned off or turned on as I'm doing here they can also be reordered so if I want to I can drag federal lands over States now I see the distribution of federal lands and the distribution of highways to change the symbols just click on the symbol maybe I want those highways to be a 1 thickness and read done let's summarize what we've done so far we've added dated with this plus sign we've added a set of data containing one two three four five six seven layers and we've also symbolized these data layers and just by simply changing the color like this great now what I want to do though is symbolize the data differently not just one color for every layer but different colors depending on the attributes of those layers so let's start with States this is the G part of G is the map there's an eye partage of GIS if I go ahead and open the table I've got a whole series of data here in this particular case I have 51 polygons or state equivalents 50 states plus Washington DC inside this data set so a GIS is not just a digital map it's a digital visual is a ssin of a database inside this table are a whole series of attributes for example we've got population data we've got ethnicity and historical data as well here's the historical data populations through the decades going back to 1790 and extending up through 2010 that means we can map any one of these variables in a variety of ways so let's go ahead and double click on there and up pops our layer properties the symbology tab is what we want right now we're mapping all the states is a beige single symbol what we want though is to map quantities let's pick the variable that we want to map how about 2010 population okay looks good all right there's our quick map of 2010 population so a choropleth map is one way I can make this data come alive another way though is instead of a graduated color map I could make a density map so I'm going to scroll down I've got the same list of variables that I can pick from and I'm going to go ahead and accept the defaults there and let's say I want to change those colors a bit I simply change the color right here maybe that color okay and now I've got one dot for every 800,000 people I can start seeing some patterns by adjusting this how about 1.4 every 100,000 people ah interesting so this is another way to visualize data how about a pie chart map okay no problem pie chart let's say we want to map 2010 population as pie chart the size we want to vary according to a population figure so I'm going to vary the size using a field the field is population 2010 maybe I want to bump down the size a bit I can always change it later if I don't like the results aha so now I I do have another way of visualizing the data I can see California Texas Illinois New York standing out Florida for example so that's another way of visualizing my data is with a pie chart or any other kind of chart I could make a bar chart or a line chart or any other kind okay let's change it back to single symbol again okay now let's go ahead and change the classification method remember we were in quantities before and we mapped on 2010 population this is where we were a little while ago let's say though that I don't want this default classification method what is the default method it's the George Jenks natural black brakes method let's go ahead and look at the distribution of the data this is where the class breaks are these blue lines and these gray bars indicate where my data sets actually fall I've got a big range of data here 563 thousand for Wyoming up to 37 million for California so I've got a big range may be natural breaks isn't the way to go maybe quantile is better quantile puts the same number of observations in every category if I have a 5 category map and approximately 50 states plus District of Columbia I'm going to have 10 observations in every one of these categories if I select quantile let's go ahead and do that okay interesting so now I've got a quantile map and I can pick out the 10 most populous states right there let's say I don't want to vary these colors the way they are I'm going to go ahead and change the color scheme let's say I want something like this where darker means more ah okay maybe that's a little easier to visualize another thing I can do is classify about standard deviation okay looks like the mean of the state populations if I look up here is 6 million just a little over 6 million there's a median and the standard deviation the sum of all the state populations in 2010 308 million which is the sum of all of the polygons in that table we looked at earlier okay I'm going to say alright now ah so now I've got States in yellow here which are close to the the mean then I've got these states in this sort of brownish color that are below the mean and then of course I've got others dates that are between a half and one and a half standard deviations above the mean and then states that have a population that falls over one and a half standard deviations above the mean some other easy things we can do is let's go ahead and change the classification method back to quantile and let's say I only want two categories two classes okay so now I have state populations from five hundred sixty-three thousand to 4.3 million then 4.3 million all the way up to 37 million now I've got two category map but let's say I want the breaking point to be something that I define so I'm going to go ahead and adjust the range here let's say I want under States under 1 million in population and then states over a million in population I want states that are in this first category to be 1 million and less and then over 1 million okay so there's my map now there are other states here that we're not looking at right there's Alaska and there's Hawaii one last thing to point out is that the G part which is the map and the eye part which is the table behind the map as we saw earlier that table are linked so if I select some states on the map for example like this let's say I'm interested in the Great Plains so I'm going to click on these states right here okay super now let's go to the attribute table and just the states that I have selected are in the table right here so what I can do is I can go to any of the fields in here and look at for example population in 2010 and I can get statistics on that five states minimum six hundred seventy-two thousand maximum three point seven five million I've got the sum which is just under ten million for these states the mean and the standard deviation and that's for population 2010 what about for the year 2000 the year 2000 was 9.2 million the sum what about in 1950 6.7 million back then conversely we can select things in the table and have them appear on the map so if we go back to our to our table now and then we're going to clear selection so now we don't have anything selected and let's say I'm interested in these states right here let's say I'm interested in Missouri Oklahoma and Kansas okay so I've selected them in the table you probably know what's going to happen if I go back to the map yep those three states are selected so the table and the map work together what's selected in the table is reflected on the map what's selected on the map is reflected in the table so they work and in hand you can also link tables together for even more powerful analysis so let's summarize what have we done we've added data we've symbolized data and we've asked some questions of the data as you can see it's really easy to change what you're mapping the fields that you're mapping it's easy to change the classification method it's easy to change the number of classes it's easy to change the colors and by doing so you are on your way to analyzing the spatial patterns of your data ah

Channel: ESRIEdTeam

Views: 26,965

Rating: 4.9629631 out of 5

Keywords: thematic, mapping, maps, ArcGIS, desktop, 10, ArcMap, Esri, GIS, symbolize, classify, software, spatial

Id: JyYTFR8y8OQ

Length: 13min 47sec (827 seconds)

Published: Thu Jul 28 2011