Python如何使用枚举和列表跳过第一（即零）迭代？

Question

I have a table object.

I want to check to see if the first row has the value of Test , in which case I need to do something with each row in the table.

Otherwise, if the first row does not have the value of Test I need to skip that row and do something with rows 1 and on.

Because I need both the index and the row, I have to use enumerate, but it seems like I am using it in a messy way. Here I am calling enumerate twice and checking to see if the index is 0 twice. Is there a more concise way to to this?

for i, r in enumerate(null_clipData.rows()):
    if r[0].val == 'Test':
        # Do something if the first row is Test
        for index, row in enumerate(null_clipData.rows()):
            if index == 0:
                continue # But do anything the first time (stay in this loop though)
            print(index, row)
        break # All through with test row

    if i == 0:
        continue # Don't do anything with the first row if the value was not Test

    print(i, r) # Do something with i and r

Answer 1

Following Kevin's advice, you can handle the first item separately, and then continue with the loop:

rows = iter(null_clipData.rows())

firstRow = next(rows)
specialHandling = firstRow.val == 'Test'

for i, r in enumerate(rows, start=1):
    if specialHandling:
        # do something special with r
    else:
        # do the normal stuff with r

Alternatively, you can also keep it in a single loop:

specialHandling = False # default case
for i, r in enumerate(null_clipData.rows()):
    if i == 0: # first item
        specialHandling = r == 'Test'
        continue

    if specialHandling:
        # do something special with r
    else:
        # do the normal stuff with r

Answer 2

rows=null_clipData.rows()
enumeration=enumerate(rows[1:])
if rows[0]=='Test':
    for idx,row in enumeration:
        print(idx,row)
else:
    for i,r in enumeration:
        print (i,r)

Something like that? I would suggest that you factor out the two different for loops into their own functions, to keep it cleaner.

just noticed Poke's answer, that too :)