variable-length

I need to find out whether a name starts with any of a list's prefixes and then remove it, like: if name[:2] in ["i_", "c_", "m_", "l_", "d_", "t_", "e_", "b_"]: name = name[2:] The above only works for list prefixes with a length of two. I need the same functionality for variable-length prefixes . How is it done efficiently (little code and good performance)? A for loop iterating over each prefix and then checking name.startswith(prefix) to finally slice the name according to the length of the prefix works, but it's a lot of code, probably inefficient, and "non-Pythonic". Does anybody have a

>>> n = [1,2,3,4] >>> filter(lambda x:x>3,n) <filter object at 0x0000000002FDBBA8> >>> len(filter(lambda x:x>3,n)) Traceback (most recent call last): File "<pyshell#3>", line 1, in <module> len(filter(lambda x:x>3,n)) TypeError: object of type 'filter' has no len() I could not get the length of the list I got. So I tried saving it to a variable, like this... >>> l = filter(lambda x:x>3,n) >>> len(l) Traceback (most recent call last): File "<pyshell#5>", line 1, in <module> len(l) TypeError: object of type 'filter' has no len() Instead of using a loop, is there any way to get the length of this

I am trying to do some vanilla pattern recognition with an LSTM using Keras to predict the next element in a sequence. My data look like this: where the label of the training sequence is the last element in the list: X_train['Sequence'][n][-1] . Because my Sequence column can have a variable number of elements in the sequence, I believe an RNN to be the best model to use. Below is my attempt to build an LSTM in Keras: # Build the model # A few arbitrary constants... max_features = 20000 out_size = 128 # The max length should be the length of the longest sequence (minus one to account for the

I have a problem with Python 3. I got Python 2.7 code and at the moment I am trying to update it. I get the error: TypeError: object of type 'map' has no len() at this part: str(len(seed_candidates)) Before I initialized it like this: seed_candidates = map(modify_word, wordlist) So, can someone explain me what I have to do? (EDIT: Previously this code example was wrong because it used set instead of map . It has been updated now.) In Python 3, map returns a map object not a list : >>> L = map(str, range(10)) >>> print(L) <map object at 0x101bda358> >>> print(len(L)) Traceback (most recent call

Is this the best way to make a variable sized struct in C++? I don't want to use vector because the length doesn't change after initialization. struct Packet { unsigned int bytelength; unsigned int data[]; }; Packet* CreatePacket(unsigned int length) { Packet *output = (Packet*) malloc((length+1)*sizeof(unsigned int)); output->bytelength = length; return output; } Edit: renamed variable names and changed code to be more correct. bk1e Some thoughts on what you're doing: Using the C-style variable length struct idiom allows you to perform one free store allocation per packet, which is half as