I was working with a machine learning model and I tried to append his output in a list for each element in antoher list.
I used a for loop but it seems like the loop jumps the first index and repeats the last ones:
x = [[0.12], [0.36], [0.48]]
print(model.run(x[0])) #this prints [-0.0006]
print(model.run(x[1])) #this prints [-0.0018]
print(model.run(x[2])) #this prints [-0.0024]
out_values = []
for value in x:
out_values.append(model.run(value))
print(out_values) #this should print [[-0.0012], [-0.0018], [-0.0024]]
# but it actually prints [[-0.0018], [-0.0024], [-0.0024]]
It doesn't seem to be a problem with the model.run() output since the first print statements worked perfectly
It must be something related to out_values.append(), because if I run:
x = [[0.12], [0.36], [0.48]]
out_values = []
out_values.append(model.run(x[0]))
out_values.append(model.run(x[1]))
out_values.append(model.run(x[2]))
print(out_values) # the result I get is still [[-0.0018], [-0.0024], [-0.0024]]
In my opinion it wasn't supposed to jump over model.run(x[0]) and repeat model.run(x[2]) twice
Is this documented or supposed to happen? Or am I doing something wrong?
I believe the issue is that model.run is returning a reference to mutable state within the model which is updated on successive run calls -- that's why there's a difference between what you print immediately after the run and what ends up in the list after additional calls. I.e. the value is correct at the time you call append, but it changes after the fact. When you call model.run(x[2]), it's modifying and returning the list that it returned when you called model.run(x[1]), and at some point it also modifies the list that was returned for x[0]. (This is not good behavior IMO -- if model is from an external library, hopefully it's at least documented in the API that you should not keep references to the return value of run! Otherwise it's just plain diabolical.)
To work around this problem so that you can keep each result as it was originally returned, make a copy of each result as you get it:
out_values = [model.run(value).copy() for value in x]
It will not skip any value or repeat any other value twice. Your model.run must be returning those values only. To remove that doubt, can you update the code to print the return value and print that like so:
for value in x:
ans = model.run(value)
print(ans)
out_values.append(ans)
Can you show output for above?
can you use this code instead?
x = (0.12, 0.36, 0.48)
print(x[0]) #this prints [-0.0006]
print(x[1]) #this prints [-0.0018]
print(x[2]) #this prints [-0.0024]
out_values = []
out_values = set(x)
print(out_values)
it'll include all x in the out_values
I am taking a user input of "components" splitting it into a list and comparing those components to a list of available components generated from column A of a google sheet. Then what I am attempting to do is return the cell value from column G corresponding the Column A index. Then repeat this for all input values.
So far I am getting the first value just fine but I'm obviously missing something to get it to cycle back and to the remaining user input components. I tried some stuff using itertools but wasn't able to get the results I wanted. I have a feeling I will facepalm when I discover the solution to this through here or on my own.
mix = select.split(',') # sets user input to string and sparates elements
ws = s.worksheet("Details") # opens table in google sheet
c_list = ws.col_values(1) # sets column A to a list
modifier = [""] * len(mix) # sets size of list based on user input
list = str(c_list).lower()
for i in range(len(mix)):
if str(mix[i]).lower() in str(c_list).lower():
for j in range(len(c_list)):
if str(mix[i]).lower() == str(c_list[j]).lower():
modifier[i] = ws.cell(j+1,7).value # get value of cell from Column G corresponding to Column A for component name
print(mix)
print(modifier)
You are over complicating the code by writing C like code.
I have changed all the loops you had to a simpler single loop, I have also left comments above each code line to explain what it does.
# Here we use .lower() to lower case all the values in select
# before splitting them and adding them to the list "mix"
mix = select.lower().split(",")
ws = s.worksheet("Details")
# Here we used a list comprehension to create a list of the "column A"
# values but all in lower case
c_list = [cell.lower() for cell in ws.col_values(1)]
modifier = [""] * len(mix)
# Here we loop through every item in mix, but also keep a count of iterations
# we have made, which we will use later to add the "column G" element to the
# corresponding location in the list "modifier"
for i, value in enumerate(mix):
# Here we check if the value exists in the c_list
if value in c_list:
# If we find the value in the c_list, we get the index of the value in c_list
index = c_list.index(value)
# Here we add the value of column G that has an index of "index + 1" to
# the modifier list at the same location of the value in list "mix"
modifier[i] = ws.cell(index + 1, 7).value
i ran into a little logic problem and trying to figure it out.
my case is as follows:
i have a list of items each item represents a Group
i need to create a set of nested groups,
so, for example:
myGroups = ["head", "neck", "arms", "legs"]
i need to get them to be represented like this:
(if you can imaging a folder structure)
head
|_> neck
|_> arms
|_>legs
and so on until i hit the last element.
what i thought would work (but don't know really how to advance here) is:
def createVNTgroups(self, groupsData):
for i in range(len(groupsData)):
print groupsData[i]
for q in range(1, len(groupsData)):
print groupsData[q]
but in this case, i am running over same elements in 'i' that i already took with 'q'.
could someone give me a hint?
thanks in advance!
If I understood well, you want a nested structure. For this case, you can use a recursive function:
myGroups = ["head", "neck", "arms", "legs"]
def createVNTgroups(alist):
temp = alist[:] # needed because lists are mutable
first = [temp.pop(0)] # extract first element from list
if temp: # if the list still contains more items,
second = [createVNTgroups(temp)] # do it recursively
return first + second # returning the second object attached to the first.
else: # Otherwise,
return first # return the last element
print createVNTgroups(myGroups)
this produces a nested list:
['head', ['neck', ['arms', ['legs']]]]
Is that what you were looking for?
>>> m
['head', 'neck', 'arms', 'legs']
>>> reduce(lambda x,y:[x,y][::-1] if x!=y else [x], m[::-1],m[-1])
['head', ['neck', ['arms', ['legs']]]]
I've got a database that I loop through, and based on certain conditions, I send the relevant database entries to a dictionary that I created. I then want to pick one randomly from this dictionary, store it in a list, clear the dictionary, and do the whole thing again with incremented variables. FYI, the ['StartNoteNum'], etc. are just column names within the cost database.
What happens though, is that it works fine the first time thorough the loop, but if I try to clear the dictionary anywhere in the code (inside or outside the while loop), then the dictionary never re-fills based on the incremented values even though it should. To confirm that it should re-fill properly, I have set the initial values to be all possible values that it would encounter in the while loop, and each one works the first time through the loop, but fails once it tries to cycle. The error I get is that the random function can't pull from an empty dictionary. Grr... here is the code.
def compute_policy(clean_midi, cost_database):
note = 0 #Setting up starting variables.
total_score = []
current_finger = 1
path = [1]
next_move = {}
while note <= 2:
current_note = clean_midi[note] #get note-pair for scoring
dest_note = clean_midi[note+1]
for each in cost_database: #find all relevant DB entries
if (int(each['StartNoteNum']) == current_note
and int(each['DestNoteNum']) == dest_note
and int(each['StartFing']) == current_finger):
next_move[int(each['DestFing'])] = int(each['Score']) #move relevant entries to separate "bin"
policy_choice = random.choice(next_move.keys()) #choose one at random
total_score.append(next_move[policy_choice]) #track the scores for each choice in a list
path.append(policy_choice) #track the chosen finger
current_finger = policy_choice #update finger variable
note += 1
path.append(current_finger) #append last finger since the loop won't run again
return total_score, path
any help here would be much appreciated. Thanks.
You are trying to use the cost_database iterator twice. After the first time you pass through it is exhausted and thus the second time you try to use it the whole for loop is skipped because it got an empty iterator.
>>> a = xrange(4)
>>> for i in a:
... print(i)
0
1
2
3
4
>>> for i in a:
... print(i)
>>> # Nothing since 'a' is already exhausted.
One possible issue is:
int(each['DestFing']) is always the same, then the same key in the dictionary will get updated and count will stay 1.
Here is my code -
cumulative_nodes_found_list = []
cumulative_nodes_found_total_list = []
no_of_runs = 10
count = 0
while count < no_of_runs:
#My program code
print 'cumulative_nodes_found_list - ' + str(cumulative_nodes_found_list)
cumulative_nodes_found_total_list.insert(count,cumulative_nodes_found_list)
print 'cumulative_nodes_found_total_list - ' + str(cumulative_nodes_found_total_list)
count = count + 1
Here is a part of the output -
#count = 0
cumulative_nodes_found_list - [0.0, 0.4693999, 0.6482, 0.6927999999, 0.7208999999, 0.7561999999, 0.783399999, 0.813999999, 0.8300999999, 0.8498, 0.8621999999]
cumulative_nodes_found_total_list - [[0.0, 0.4693999, 0.6482, 0.6927999999, 0.7208999999, 0.7561999999, 0.783399999, 0.813999999, 0.8300999999, 0.8498, 0.8621999999]]
#count = 1
cumulative_nodes_found_list - [0.0, 0.55979999999999996, 0.66220000000000001, 0.69479999999999997, 0.72040000000000004, 0.75380000000000003, 0.77629999999999999, 0.79679999999999995, 0.82979999999999998, 0.84850000000000003, 0.85760000000000003]
cumulative_nodes_found_total_list -[[0.0, 0.55979999999999996, 0.66220000000000001, 0.69479999999999997, 0.72040000000000004, 0.75380000000000003, 0.77629999999999999, 0.79679999999999995, 0.82979999999999998, 0.84850000000000003, 0.85760000000000003],
[0.0, 0.55979999999999996, 0.66220000000000001, 0.69479999999999997, 0.72040000000000004, 0.75380000000000003, 0.77629999999999999, 0.79679999999999995, 0.82979999999999998, 0.84850000000000003, 0.85760000000000003]]
As the new item is appended the old item is replaced by new item. This trend continues.
Can anyone tell me why this is happening. I have tried using 'append' in place of insert but got the same output. However when I use 'extend' I get the correct output but I need inner items as lists which I dont get with extend.
You need to rebind cumulative_nodes_found_list at the beginning of the loop, instead of just clearing it.
This is psychic debugging at its best, since you're effectively asking "what is wrong with my code, which I'm not going to show to you".
All I can do is assume.
I'm assuming you're re-using the array objects in memory.
In other words, you do something like this:
list1.insert(0, list2)
list2.clear()
list2.append(10)
list2.append(15)
list1.insert(0, list2)
Since list1 points to the same array/list the whole time, and you're adding a reference to the object, and not a copy of it, later changes will make it appear your copy changed.
In other words, the result of the code above is going to be:
[[10, 15], [10, 15]]
regardless of what was in the list before you added it the first time.
Try assigning the changing list a new, empty, object each time you enter the loop body and see if that fixes anything.
You are adding a reference to cumulative_nodes_found_list to the cumulative_nodes_found_total_list, but it's the same reference each time. Move this line into the loop body:
cumulative_nodes_found_list = []
Lists are mutable objects. You're mutating cumulative_nodes_found_list inside your code, so the object added to your total list in the previous run is also mutated, because they are the same object.
Either make a copy to insert in the total:
for count in xrange(no_of_runs):
# ...
cumulative_nodes_found_total_list.append(list(cumulative_nodes_found_list))
... or reset the list on each iteration:
for count in xrange(no_of_runs):
cumulative_nodes_found_list = [] # creates a NEW list for this iteration
# ...
cumulative_nodes_found_total_list.append(cumulative_nodes_found_list)
I believe the problem is in the rest of your program code.
The items in cummulative_nodes_found_list is being replaced in-place each time through the loop.
I assume you're doing something like this:
while count < no_of_runs:
cummulative_nodes_found_list.clear()
#fill up the list with values using whatever program logic you have
cummulative_nodes_found_list.append(1.1)
cummulative_nodes_found_list.append(2.1)
print 'cumulative_nodes_found_list - ' + str(cumulative_nodes_found_list)
cumulative_nodes_found_total_list.insert(count,cumulative_nodes_found_list)
print 'cumulative_nodes_found_total_list - ' + str(cumulative_nodes_found_total_list)
count = count + 1
if this is, infact, what you're doing, then instead of using 'clear()' to clear the list, create a new one:
ie, replace cummulative_nodes_found_list.clear() with
cummulative_nodes_found_list = []
My guess is that you are not assigning the cumulative_nodes_found_list to be a new list each time, but updating its contents instead. So each time around the loop you are adding the same list reference to the total list. Since the reference within the totals list is the same object, when you update this list the next time around the loop, it affects what you hoped was the last loops values.
If you want to append to a list, use mylist.append(item) instead.
Also, if you iterate a fixed number of times it's better to use a for loop:
for i in range(no_of_runs):
# do stuff
The idea is, that range(no_of_runs) generates the list [0, 1, 2, ..., 10] for no_of_runs = 10 and the loop then iterates over its values.
Edit: this doesn't solve the problem. Other answers in this thread do, however. It's just a comment on style.
This method worked for me. Just like you, I was trying to append/insert a list into another list.
cumulative_nodes_found_total_list.insert(count,cumulative_nodes_found_list)
But the old values were being appended by the new values. So instead I tried this -
cumulative_nodes_found_total_list.insert(count,cumulative_nodes_found_list[:])
"Assignment statements in Python do not copy objects, they create
bindings between a target and an object."
Use deepcopy (or copy)