![]() ![]() ValIter = itertools.imap(int, itertools.chain(itertools.imap(str. The function takes a string as input and returns an integer as its output. To convert a string to an integer, use the built-in int() function. This version has the added benefit of creating a number iterator, so you can spool only one or several numbers out of the file at a time, instead of one billion in one shot. How to convert a string to int in Python. If there are multiple values per line that are white space separated, dig into the itertools to keep the looping code out of Python. ![]() If it is a single number per line, you could reduce the code to values = map(int, open("numberfile.txt")) The map function here can be your friend. ![]() We can use either the float value itself or a variable: print (str (421.034)) f 5524. When we pass a float into the str() method, a string value of the float will be returned. Get your looping out of Python entirely if possible. If we are looking to convert a float to a string rather than an integer to a string, we follow the same steps and format. Appending these to a list, one at a time, is going to require several large reallocations. Consider using some iterators to give you only a few values at a time A billion numbers will take a bit of storage. The int function is a global, so looking it up will be more expensive than a local.ĭo you really need all billion numbers in memory at all times. One common scenario in Python programming is converting strings to integers or other data types. You will get some percentage of speed by ensuring only "local" variables are used in your tightest of loops. Published on Python is a versatile programming language that offers an extensive range of built-in functions and features for handling different data types. > strings: array n: to-integer 1e7 repeat i n > delta-time ]Īs John noted in the comments, this version does not build a list of converted integers, so the speed-ratio given is relative to Python's 4.99s runtime of for str in strings: int(str). For example, 150 is a string containing the number 150. Integer as string in Python Whole numbers in Python are generally stored using the int type and in some cases as a string. Python 2.6.2 with IPython 0.9.1, ~214k conversions per second (100%): In : strings = map(str, range(int(1e7))) In this tutorial, we will look at how to convert an integer ( int datatype) in Python to a string with the help of some examples. The host machine is running 64-bit Linux. The time it takes reading the data is irrelevant here, processing the data is the bottleneck.Īll of the following are interpreted languages. What I'm really thinking about is some semi-hidden Python functionality that could be (ab)used for this purpose, not unlike Guido's use of array.array in his "Optimization Anecdote". Therefore the question: what is the fastest way possible to convert a string to an integer, in Python? Why? And more importantly: how to make it faster? Conversion using int() is horribly slow compared to other tools working on the same dataset. T = threading.A simple problem, really: you have one billion (1e+9) unsigned 32-bit integers stored as decimal ASCII strings in a TSV (tab-separated values) file. Res_dict = (pre + str(int(tmp)))ĭigits = math.floor(math.log10(factorial))+1 Tmp = (factorial % 10 ** (each_thread * (max_thread - threadID + 1))) // 10 ** (each_thread * (max_thread - threadID)) Res_dict = (str(int(factorial % 10 ** (each_thread * 1)))) ![]() Res_dict = (str(factorial // 10 ** (each_thread * (max_thread - 1)))) four space string should return 0x20202020. ╚═══╩════════════╩═════════════╩══════════════╩═══════════════════╝Īnyway, I think you can do it faster with multi-threading.ĭef int_str(threadID, each_thread, max_thread): python - Fast and efficient way to convert string into integer - Stack Overflow Fast and efficient way to convert string into integer Ask Question Asked 3 years, 7 months ago Modified 3 years, 7 months ago Viewed 982 times 2 I want to convert four character string text into 32bit integer number, e.g. ║ ║ Count ║ Compute(s) ║ Convert(s) ║ M.T Convert(s) ║ Print(end - start, "Seconds to convert and save") If you have any segestions / solutions let me know! Anything will help. I am using the generic a = str(a) but fell like there is a better way like using a buffer or library. I will put an example of computation and int conversion time. I have tried to find a fast way to convert an int to string. I am solving massive factorials in python and have found that when I am done calculating the factorial it takes the same time to convert to string to save to a file. ![]()
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