How do I determine if an element is in a list?

thelist = [{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}]

How do I say:

开发者_运维知识库If "red" is in thelist and time does not equal 2 for that element (that's we just got from the list):

Using any() to find out if there is an element satisfying the conditions:

>>> any(item['color'] == 'red' and item['time'] != 2  for item in thelist)
False

def colorRedAndTimeNotEqualTo2(thelist):
    for i in thelist:
        if i["color"] == "red" and i["time"] != 2:
            return True
    return False

print colorRedAndTimeNotEqualTo2([{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}])

for i in thelist iterates through thelist, assigning the current element to i and doing the rest of the code in the block (for each value of i)

Thanks for the catch, Benson.

Well, there's nothing as elegant as "find" but you can use a list comprehension:

matches = [x for x in thelist if x["color"] == "red" and x["time"] != 2]
if len(matches):
    m = matches[0]
    # do something with m

However, I find the [0] and len() tedious. I often use a for loop with an array slice, such as:

matches = [x for x in thelist if x["color"] == "red" and x["time"] != 2]
for m in matches[:1]:
    # do something with m

list = [{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}]
for i in list:
  if i['color'] == 'red' && i['time'] != 2:
    print i

for val in thelist:
    if val['color'] == 'red' and val['time'] != 2:
        #do something here

But it doesn't look like that's the right data structure to use.

You can do most of the list manipulation in a list comprehension. Here's one that makes a list of times for all elements where the color is red. Then you can ask if 2 exists in those times.

thelist = [{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}]
reds = ( x['time'] == 2 for x in thelist if x['color'] == red )
if False in reds:
  do_stuff()

You can condense that even further by eliminating the variable "reds" like this:

thelist = [{'color':'green', 'time':4}, {'color':'red','time':2},{'color':'blue','time':5}]
if False in ( x['time'] == 2 for x in thelist if x['color'] == red ):
  do_stuff()