I have a table of ~3,000 invoices that are from 40 different vendors. In MS Access 2013, how would I randomly pick one record from each of the 40 vendors?
vendredi 24 juillet 2015
calling a method in java and incrementing an array in a for loop
Hi i am new to programming, my program is a random number generator using the math.random class and i am having issues with my code. I need to Call the randInt method n times in the randTest method, each time incrementing the count of the element counts corresponding to the value returned. Basically each time a random number is generated, the counts element increases.
This is my code so far:
public class RandNumGenerator {
public static int RandInt(){
int n = (int) Math.random()*10;
return n;
}
public static void randTest(int n){
int [] counts = new int [10];
for(int i=0;i<10;i++){
RandInt();
}
}
}
JAVA - How can i read random proxys from txt?
i have a File.txt in mi pc, so i know how read it sequentially using this simple method:
FileReader fl = new FileReader("C:/Users/Silver/Desktop/proxy.txt");
BufferedReader br = new BufferedReader(fl);
for(;;){
String read = br.readLine();
System.out.println(read);
Thread.sleep(100);
if (read == null) {
System.out.println("No More proxys");
br.close();
}
And this read until there are no more proxys, so i wanna know an easy method to do the same but this time randomly, i read about a method called "LineNumberReader" somebody that know about this can explain to me?
Thanks so much.
Modify values in random rows of a data.table by category
I have a data.table with two columns, let's say city and score
data.table(city = sample(c("Cape Town", "New York", "Tel Aviv"),size=15, replace = TRUE), score = sample(x=1:10, size = 15, replace=TRUE))
city score
1: Tel Aviv 5
2: New York 5
3: New York 8
4: Cape Town 10
5: Tel Aviv 7
6: New York 10
7: Tel Aviv 8
8: Cape Town 2
9: Tel Aviv 2
10: Cape Town 2
11: Cape Town 5
12: New York 1
13: Tel Aviv 3
14: Cape Town 6
15: New York 5
I want to change the score to 0 to two random rows per city (i.e., 2 rows for Tel Aviv, two for New York, etc.). Please mind that there will always be more than two rows for every city (my real data are quite large...). Ideally, I would like a solution based on data.table commands... Thank you!
Selecting Random Record for each User returned in the results
I have seen several ways of selecting random records from a table using several methods. However, my need I am sure is here, I just cannot find it. I have a query using several tables. What my end goal is is to have one random record for each user returned.
In my result set, I get users and the work items they have. What I need is to only return one random work item per user. This is where I am getting stuck. ANy assistance would be greatly appreciated.
Creating and accessing images using a for loop and if statements
Currently I am working on a simple children's counting game where you have to count the number of images shown on screen and pick the right answer to get points and win.
What I want is to be able to get a random image selected using a random number generator and depending on the number, get an image associated with it. So for this assignment I have made the image names to numbers and instead of using an if statement for all of them, I was hoping to use the number generated to be able to grab the image i wanted.
eg. int randomImage = random.Next(0,15); if the randomImage number is 6, it would pick the image named 6.png.
I was wondering if anybody knows of a way to do this. my attempt was along the lines of: pictureBox2.image = randomImage + ".png";
It might seem a little advanced but i hope somebody could help. Thank you very much
Why doesn't my definition of this function lead to the desired outcome?
Why doesn't my definition of propmt_int not work? Its original defintion was:
def prompt_int(prompt=''):
while True:
val = input(prompt)
try:
return int(val)
except:
print("Not a valid number, please try again")
but that didn't work either and it doesn't work when I remove the statement right at the start of my code> Im really stuck please help. here is the whole of my code:
import random
status = input("Are you a teacher or student? Press 1 if you are a student or 2 if you are a teacher")
def prompt_int(prompt=''):
while True:
if status == prompt_int(prompt=''):
val = input(prompt)
if val in (1,2):
return int(val)
return true
elif status != prompt_int(prompt=''):
val = input(prompt)
if val in (1,2,3):
return int(val)
return true
else:
print("Not a valid number, please try again")
def get_bool_input(prompt=''):
while True:
val = input(prompt).lower()
if val == 'yes':
return True
elif val == 'no':
return False
else:
print("Not a valid input (yes/no is expected) please try again")
status = prompt_int("Are you a teacher or student? Press 1 if you are a student or 2 if you are a teacher")
if status == "1":
score=0
name=input("What is your name?")
print ("Alright",name,"welcome to your maths quiz."
" Remember to round all answers to 5 decimal places.")
level_of_difficulty = int(input(("What level of difficulty are you working at?\n"
"Press 1 for low, 2 for intermediate "
"or 3 for high\n")))
if level_of_difficulty not in (1,2,3):
sys.exit("That is not a valid level of difficulty, please try again")
if level_of_difficulty == 3:
ops = ['+', '-', '*', '/']
else:
ops = ['+', '-', '*']
for question_num in range(1, 11):
if level_of_difficulty == 1:
number_1 = random.randrange(1, 10)
number_2 = random.randrange(1, 10)
else:
number_1 = random.randrange(1, 20)
number_2 = random.randrange(1, 20)
operation = random.choice(ops)
maths = round(eval(str(number_1) + operation + str(number_2)),5)
print('\nQuestion number: {}'.format(question_num))
print ("The question is",number_1,operation,number_2)
answer = float(input("What is your answer: "))
if answer == maths:
print("Correct")
score = score + 1
else:
print ("Incorrect. The actual answer is",maths)
if score >5:
print("Well done you scored",score,"out of 10")
else:
print("Unfortunately you only scored",score,"out of 10. Better luck next time")
class_number = prompt_int("Before your score is saved ,are you in class 1, 2 or 3? Press the matching number")
filename = (class_number + "txt")
with open(filename, 'a') as f:
f.write("\n" + str(name) + " scored " + str(score) + " on difficulty level " + str(level_of_difficulty + "\n"))
with open(filename, 'a') as f:
f = open(filename, "r")
lines = [line for line in f if line.strip()]
f.close()
lines.sort()
if get_bool_input("Do you wish to view previous results for your class"):
for line in lines:
print (line)
else:
sys.exit("Thanks for taking part in the quiz, your teacher should discuss your score with you later")
if status == "2":
class_number = prompt_int("Which classes scores would you like to see? Press 1 for class 1, 2 for class 2 or 3 for class 3")
filename = (class_number + "txt")
with open(filename, 'a') as f:
f = open(filename, "r")
lines = [line for line in f if line.strip()]
f.close()
lines.sort()
for line in lines:
print (line)
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