How do I create a list of floats in Python?

Question

I am having an issue of creating an array of floats. I have a loop that is scanning the rows of an attribute table and extracting numbers from it. SARAarea, truearea and rasterarea are all extracted from an attribute table and they should be floats. I am trying to use these numbers and do calculations with them and then insert them back into the attribute table. My main issue is adding floats to the list. I keep getting error messages that a float is not iterable or a float is not an attribute to append or extend. What is the best way to do this? I tried to create one loop that would getvalue and insert value into the attribute without using a list. But the searchcursor function only allows me to create two separate loops because there is a seachCursor and a UpdateCursor, it only allows me to do one task at a time. This is my attempt at initializing the lists approxTen=['f'] approxremaining=['f'] lessperc=['f'] moreperc=['f']‍‍‍‍‍‍‍‍ This is where I am getting my errors. The code is in a while loop of a searchCursor. "While row:". approxTen=(SARAarea*truearea)/rasterarea approxremaining=truearea-approxTen lessperc=(approxTen/truearea)*100 moreperc=(approxremaining/truearea)*100 approxTen.append(approxTen) approxremaining.append(approxremaining) lessperc.append(lessperc) moreperc.append(moreperc)‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍ Common error I am getting below. Line 50 is line 7 in the code above. I have tried extend and append but neither worked and I haved tried putting float() around the values of approxTen and the rest of them but it did not work. For example: approxremaining= float(truearea-approxTen) This is how I am inserting it back into the attribute table. Below is a separate loop then above code. I am trying to loop through the list and add it to the attribute table. while row3: row3[0]=approxTen[row3] row3[1]=approxremaining[row3] row3[2]=lessperc[row3] row3[3]=moreperc[row3] cursoru.updateRow(row3)‍‍‍‍‍‍‍‍‍‍‍‍

curtvprice · Answer

Though, Dan, I would recommend using the newer arcpy.da.UpdateCursor as its performance is 10-100x faster.

UpdateCursor—Help | ArcGIS Desktop

DanPatterson_Retired · Answer

You updated one row... examine updatecursors and examine the code snippet in the help files to get the proper syntax

bixb0012 · Answer

You will need to post more code, not necessarily all, but more of the functional parts.  With the snippets you have posted here, it is hard to provide specific suggestions.  The structure of your code snippet, i.e., the way you are using a while loop, is not very idiomatic.  As best I can tell, even though you may be looping over row3, you are not moving the cursor, so you appear to be continually updating the same row.