CODEWITHSUNDEEP
pythonlistindexingboolean
user1106770
user1106770

Reputation: 1449

Python: How to access only some boolean elements of a list with a loop?

I have list like this: listvalues = [True, True, False, True, False, 24, somestring, 50] So the first five elements of the list are booleans, the rest are strings and ints. Now I want to check the first five elements if they are true or false, and if they are true, I want to use a certain method, depending on the index of the element. So, in the case above, one action should be made for the first element (index 0), then another action for the second element (index 1), then another action for the forth element. If all of the booleans are false a warning should appear. Sorry for the noob question, but I couldn't find a short and easy solution by myself...

Upvotes: 2

Views: 2557

Answers (5)

joaquin
joaquin

Reputation: 85613

Given you already defined the functions you want to apply for each case, you can put them in a list to call them in the loop

perform = [func1, func2, func3, func4, func5]

if not any(listvalues[:5]): raise Exception

for index in range(5):
    if listvalues[index]:
        func = perform[index]
        func()

Upvotes: 1

Karoly Horvath
Karoly Horvath

Reputation: 96258

is there a warning if there are no booleans?

if not any(filter(lambda x: type(x)==bool, listvalues)):
    print "warning"
else:
    filter(lambda x: type(x[1])==bool and x[1]==True, enumerate(listvalues))

sorry, forgot the first 5 element part, just slice it.. and no need to check bool...

Upvotes: 0

Zhack
Zhack

Reputation: 96

if your_list[:5] == [False,False,False,False,False]:
    print 'warning'
else:
    method1(your_list[0])
    method2(your_list[1])
    method3(your_list[2])
    method4(your_list[3])
    method5(your_list[4])

def method1(myBool):
    if myBool == False:
        return
    --- method content ---

def method2(myBool):
    if myBool == False:
        return
    --- method content ---
...

Would be my solution.

Upvotes: 0

g.d.d.c
g.d.d.c

Reputation: 47978

There are a number of things that might help here. First off, you should use list slicing to isolate the booleans. If you know the first 5 elements are what you're after, then myList[0:5] will get just those and ignore the others.

Next, look into the any function. It'll return True if any of the elements is True, so you might do this to decide if you need to issue the warning:

if not any(myList[0:5]):
  # Code here to issue the warning.

Next, to deal with which functions to call, you'd probably want something like this:

funcList = [f0, f1, f2, f3, f4]
for idx, test in enumerate(myList[0:5]):
  if test: funcList[idx]()

Ideally though, what would probably work better would be to put references to the individual functions in the original list, instead of booleans, with a value of None if you wanted to skip that function. Your original list would end up looking like this:

myList = [f1, f2, None, f3, None, 24, "string", 50]

To call the ones that you want to call you'd do this:

for func in myList[0:5]:
  if func is not None: func()

Upvotes: 3

matt b
matt b

Reputation: 139921

all_false = True
for x in yourlist:
   if x is True:
       # call some method
       # ...
       all_false = False

if all_false:
    # print warning

Upvotes: 1

Related Questions