试图找出列表中的位置

Question

For example I am looking for a way to search every spot in a list to see where an object is located. Some example psuedocode could go:

for every column in current row:
  if column is the first one:
                  do this
  if column in the last one:
                  do that
  else:
     find the previous row and columns place

Basically I am at a standstill so any insight would be helpful thanks

EDIT Sample Code:

for row in range(0,h+1):
      newrow=[]
      if row==0:
           newrow=[1]
      elif row==1:
           newrow=[1,1]
      else:
          for column,x in enumerate(row):
              if column==0:
                  newrow.append(1)
              elif column==len(row)-1:
                  newrow.append(1)
              else:
                  newrow.append(2)

Answer 1

Are you looking for list.index ?

l = ['foo', 'bar', 'baz']
i = l.index('bar')
# i is 1, because l[1] == 'bar'

If you need special handling based on whether it's the first or last item:

# using i from above
if i == 0:
    # it's the first item
elif i == len(l) - 1:
    # it's the last item
else:
    # it's neither first nor last

Or if you need to process all items anyway, consider using enumerate to keep track of indices throughout the loop:

for i, x in enumerate(mylist):
    if i == 0:
        # x is the first item
    elif i == len(mylist)-1:
        # x is the last item
    else:
        # x is in the middle

Answer 2

bardockyo:

The problem appears to be that you don't have a list in row... when you run the code 'for row in range(0,h+1):', row will always be an integer with a value between greater than or equal to 0, and less than or equal to h.

Are you trying to read a file a row at a time, and keep track of the row numbers? If so, you should use a separate counter to track the row number...

I can't quite follow what you're trying to accomplish, so I can't even generate code to help you...

Added in response to bardockyo's comment:

I believe this accomplishes your goal:

# Setting h to a value so that I can use your 'range' line.
h = 5

# Create a blank dictionary object to store the row data.
rows = {}

for row_number in range(0,h+1):
    row_data = []
    # range isn't inclusive of the end value by default, to 'make it work', we
    # must add 1 to the row_number.
    for val in range(0,row_number+1):
        if val == 0 or val == row_number:
            # Determine if the value in 'val' is either the first number or
            # last number in this row, and if so append '1' to the list.
            row_data.append(1)
        else:
            # Determine if the value in 'val' is not the first number or last
            # number in this row, and if so append '2' to the list.
            row_data.append(2)
    # Store the row data in the row dictionary, with the key of 'row_number'.
    rows[row_number] = row_data

# Iterate through the dictionary.  There's no guarantee as to the order
# returned by the 'keys()' function, so I use sorted() to ensure it's in
# numerical order.
for row_num in sorted(rows.keys()):
    print 'Row Number %d contains the list:' % row_num,
    for val in rows[row_num]:
        print '%d' % val,
    print ''

# There are better (read: cleaner) ways to format the output for printing,
# but they can be hard to read.