random

问题 I would like to make a random ICMP traffic using ping. I need to make a random decimal number between 0.5 to 1 for time parameter in my code. Could you please show me how to make uniform random decimal number? My code just can make a integer number. Thanks #!/bin/bash for ((i = 0; i <=100; i++)) do #need to have random number between 0.5 to 1 for time time=$(($RANDOM%5+1)) num=$(($RANDOM%5+1)) ping -c $num -i $time 10.0.0.2 done 回答1: bash doesn't actually do decimal number, only integers, but

问题 I have a random_rand() function which produces a random number between 0 and RANDOM_RAND_MAX. RANDOM_RAND_MAX is defined to be 65535. I would like to use the middle bits from the result of random_rand() instead of lowest-order bits so that I can make the randomiztion better. Could you please show me a quick way to do this. Thanks 回答1: That's naughty. Linear congruential generators work in such a way that the "most random" part comprises the lower order bits. A very famous IBM implementation

问题 I want to shuffle an array, but all I find was method like random.shuffle(x) , from Best way to randomize a list of strings in Python Can I do something like import random rectangle = [(0,0),(0,1),(1,1),(1,0)] # I want something like # disorderd_rectangle = rectangle.shuffle Now I can only get away with disorderd_rectangle = rectangle random.shuffle(disorderd_rectangle) print(disorderd_rectangle) print(rectangle) But it returns [(1, 1), (1, 0), (0, 1), (0, 0)] [(1, 1), (1, 0), (0, 1), (0, 0)]

问题 I want to shuffle an array, but all I find was method like random.shuffle(x) , from Best way to randomize a list of strings in Python Can I do something like import random rectangle = [(0,0),(0,1),(1,1),(1,0)] # I want something like # disorderd_rectangle = rectangle.shuffle Now I can only get away with disorderd_rectangle = rectangle random.shuffle(disorderd_rectangle) print(disorderd_rectangle) print(rectangle) But it returns [(1, 1), (1, 0), (0, 1), (0, 0)] [(1, 1), (1, 0), (0, 1), (0, 0)]

问题 I would like to be able to generate a random number from a group of numbers, like for example: 1, 2, 3, 12, 11, 23, 45, 54, 10, 10, 12, 23, 35, 24. Using the rand and the srand i can generate random numbers different each time but i would like to able to condition the outcomes by generating random numbers from a group. 回答1: Example code Take an Array int a[]={ 1, 2, 3, 12, 11, 23, 45, 54, 10, 10, 12, 23, 35, 24}; int i = rand()%14; // here 14 is number of element in array. i will receive a

问题 I need a truly random BMP in order to test various lossy image compression algorithms. Ideally, this would not rely on any library and run in a Linux CLI. It should generate a random BMP given a certain width and height . 回答1: You can use ImageMagick (which is installed on most Linux distros by default) to generate an image of random noise like this: convert -size 300x200 xc:gray +noise random out.bmp where 300 is the width and 200 is the height (just examples). Other types of noise are

问题 I'm going to run modified DES code(C language) on the PIC18F2550 microcontroller. For this I am using mplabx IDE v 2 and Mplab xc8 v 1.30. To modify the code, I need a random number so that each run will produce different numbers. I want to use the rand function but I need a good seed for Srand function! Good seed can be time, but since there is no such thing as a micro or I do not know!! 回答1: You can store an integer value in EEPROM. When the device boots, you use it as a seed and then

问题 I want to generate a sample of integer numbers in R with a specified mean. I used mu+sd*scale(rnorm(n)) to generate a sample of n values that has exactly the mean= mu but this generates floating-point values; I would like to generate integer values instead. For example, I would like to generate a sample of mean=4. My sample size n =5, an example of generated values would be {2,6,4,3,5}. Any ideas on how to do this in R while satisfying the constraint of a specific value of the mean? 回答1:

问题 The intention of following (simplified) code fragment is to return one random row . Unfortunatly, when we run this fragment in the query analyzer, it returns between zero and three results. As our input table consists of exactly 5 rows with unique ID's and as we perform a select on this table where ID equals a random number, we are stumped that there would ever be more than one row returned. Note: among other things, we already tried casting the checksum result to an integer with no avail.

问题 I'd like to generate a random number with each digit being in range from 0-9 and not repeating itself. Assume finite length of 4. 1234 qualifies, each composite digit is unique. 1123 does not, 1 is repeated How can this be done please? 回答1: To generate the digits: std::vector<int> vec = {0,1,2,3,4,5,6,7,8,9}; // or initialize from array if not c++11 std::random_shuffle(vec.begin(), vec.end()); vec.resize(4); And to join the digits into a single number: int number = 0; for (auto i = vec.begin(