Loops
Loops are everywhere
- Many automated tasks involve loops
- We need to tell a computer to do something...
- until a condition it met
- or for a certain number of times
"Hi, Python, can you do this like...10 times?"
The for loop
So we have this file with lines of stuff
How do we read that in?
We're going to read in a file
We'll look at this more in later weeks, so just roll with not getting the styntax for now
1 Delaware
2 Pennsylvania
3 New Jersey
4 Georgia
5 Connecticut
6 Massachusetts
7 Maryland
8 South Carolina
9 New Hampshire
10 Virginia
11 New York
12 North Carolina
13 Rhode Island
14 Vermont
15 Kentucky
16 Tennessee
17 Ohio
18 Louisiana
19 Indiana
20 Mississippi
21 Illinois
22 Alabama
23 Maine
24 Missouri
25 Arkansas
26 Michigan
27 Florida
28 Texas
29 Iowa
30 Wisconsin
31 California
32 Minnesota
33 Oregon
34 Kansas
35 West Virginia
36 Nevada
37 Nebraska
38 Colorado
39 North Dakota
40 South Dakota
41 Montana
42 Washington
43 Idaho
44 Wyoming
45 Utah
46 Oklahoma
47 New Mexico
48 Arizona
49 Alaska
50 Hawaii
These are tabs
>>> with open('states.txt','rt') as states:
... states = states.readlines()
...
>>> print type(states)
<type 'list'>
>>> print states[:2]
['1\tDelaware\n', '2\tPennsylvania\n']
>>> #oo, look at those tabs! if only I could do something...
...
>>> splitstates = []
>>> for state in states:
... splitstates.append(state.split())
...
>>> print splitstates[:2]
[['1', 'Delaware'], ['2', 'Pennsylvania']]
>>> # woohoo!
...
So that's neat, we have data, now let's do stuff to it
>>> for state in splitstates:
... num = state[0]
... name = state[1]
... print name, "is state", num
...
Delaware is state 1
Pennsylvania is state 2
New is state 3
Georgia is state 4
Connecticut is state 5
Massachusetts is state 6
.....snip......
A formula for "srsly, just do this like 10 times"
range() is your friend
Combo range() with for to execute something a bunch
Doing stuff until something...
When you don't know how many times it will be
Loops
By Elizabeth W.
Loops
- 803