代码中的Python缩进错误

Question

Please, firstly, is there an IDE where indentation is being taken care of? secondly, I have an indentation error in my code. Could anyone point out where the indentation is needed in my code?

p = [0.2,0.2,0.2,0.2,0.2]

world = ['green','red','red','green','green']
z = 'red'
pHit = 0.6
pMiss = 0.2
def sense(p, z):
  q=[]
  for i in range(len(p)):
      hit = (z==world[i])
      q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
      return q

print sense(p,z)

Answer 1

1. Is that code right?? (The indentation)
2. Your return doesn't seem to be in the right place.
3. Please! Please!! Please!!! Follow PEP-8 for naming of variables and coding style.
4. No, There is no IDE that can read your mind, and guess what indent you want on a certain statement...

But, you can re-indent your code:

p = [0.2,0.2,0.2,0.2,0.2]

world = ['green','red','red','green','green']
z = 'red'
pHit = 0.6
pMiss = 0.2
def sense(p, z):
  q=[]
  for i in range(len(p)):
      hit = (z==world[i])
      q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
  return q # dedented

print sense(p,z)

Answer 2

In python you can use tabs or spaces as indentation, but you must remain consistent in what you use and how many of them there are. Take a closer look at the following:

def sense(p, z):
  q=[]
  for i in range(len(p)):
      hit = (z==world[i])
      q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
      return q

Whether or not the return statement is where it belongs, the issue is with the lines

  q=[]
  for i in range(len(p)):

relative to

  for i in range(len(p)):
      hit = (z==world[i])
      q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
      return q

Notice how there are TWO spaces before the first two lines mentioned and SIX spaces before the body of the for loop. Every indentation level should be a multiple of a single indent. So if you want to use two spaces:

def sense(p, z):
  q=[]
  for i in range(len(p)):
    hit = (z==world[i])
    q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
    return q

and if you want to use four spaces:

def sense(p, z):
    q=[]
    for i in range(len(p)):
        hit = (z==world[i])
        q.append(p[i]*(hit*pHit + (1-hit)*pMiss))
        return q

I typically go with four and set up my environment to map the tab character to four spaces.

That said...I too agree on moving the return statement. But at least now you can run your code and figure out if/why you want to move it.

You should probably read through all of PEP-8 , but particularly the section on indentation

Answer 3

Your return statement is not in the right place. Additionally, pHit , pMiss and world variables should be defined in a function scope:

def sense(p, z):
    pHit = 0.6
    pMiss = 0.2
    world = ['green','red','red','green','green']

    q = []
    for i in range(len(p)):
        hit = (z==world[i])
        q.append(p[i] * (hit * pHit + (1 - hit) * pMiss))
    return q

p = [0.2,0.2,0.2,0.2,0.2]
z = 'red'
print sense(p,z)