I have an array that would has 0-49. When I compare acc_x[i] > acc_x[i-1], it would work for some value until it is comparing 5 and 4, then it say that 4 is bigger than 5 and go into the else statement. Please help.
int main(int argc, const char * argv[])
{
#autoreleasepool {
// insert code here...
//NSLog(#"Hello, World!");
//use velocity not acceleration. sorry for the naming. so run the velocity function for the array first that I wrote a already
NSMutableArray * acc_x = [NSMutableArray array];
NSNumber * temp = 0;
//the highest point or lowest point
NSNumber *highest =0;
NSNumber *lowest = 0;
int flag = 0;
//array for the highest and lowest point
NSMutableArray * array_lowest = [NSMutableArray array];
NSMutableArray * array_highest = [NSMutableArray array];
//array for the time when the highest and the lowest point
NSMutableArray * time_lowest = [NSMutableArray array];
NSMutableArray * time_highest = [NSMutableArray array];
double temp1 = 0;
NSNumber *temp2 = 0;
// the time variable is is just for temp variable. the real variable will be how long it take to have one measurement. i think it was like .001 or something like that but i don't remember. the time have to be in second if it is not in second the conver it.
double time = 0.1;
//trying to find the highest point or the lowest points in the graph from the acceleration
for (int i=0; i<50; i++)
{
//putting 0-49 into the array for testing
temp = [NSDecimalNumber numberWithDouble:i];
[acc_x addObject:temp];
if(i == 2) {
if (acc_x[i] > acc_x[i-1]) {
flag = 0;
}
if(acc_x[i] < acc_x[i-1]){
flag = 1;
}
NSLog(#"flag = %d",flag);
}
if(i>1) {
if(acc_x[i] > acc_x[i-1]) {
NSLog(#"x now is bigger then x past");
}
}
if(i >1) {
if(acc_x[i] > acc_x[i-1]) {
NSLog(#"x now is bigger then x pass");
}
NSLog(#"i = %d , i-1 = %d",i, i-1);
if (flag == 0) {
NSLog(#"flag is 0");
if(acc_x[i] > acc_x[i-1]) {
highest = acc_x[i];
}
else {
NSLog(#"flag going to turn into 1");
[array_highest addObject:highest];
flag = 1;
// calculate the time when the highest point is
temp1 = time * i;
temp2 = [NSNumber numberWithDouble:temp1];
[time_highest addObject:temp2];
}
}
if (flag ==1) {
NSLog(#"flag is 1");
}
}
}
// the size of the array
/* long size = [acc_x count];
for (int i =1; i<size-1; i++) {
NSLog(#"i = %d, flag = %d, array = %#, array[i-1] = %#",i,flag,acc_x[i],acc_x[i-1]);
if (flag == 1) {
if (acc_x[i] < acc_x[i-1]) {
lowest = acc_x[i];
}
if (acc_x[i] > acc_x[i-1]) {
flag = 0;
[array_lowest addObject:lowest];
// the temp1 is storing the time when this point got recorded
temp1 = time * i;
temp2 = [NSNumber numberWithDouble:temp1];
[time_lowest addObject:temp2];
}
}
if (flag == 0) {
if (acc_x[i] > acc_x[i-1]) {
highest = acc_x[i];
NSLog(#"x now is bigger than x-1");
//NSLog("highest = %d", highest);
}
if (acc_x[i] < acc_x[i-1]) {
NSLog(#"x now is less than x-1");
flag = 1;
[array_highest addObject:highest];
// the temp1 is storing the time when this point got recorded
temp1 = time * i;
temp2 = [NSNumber numberWithDouble:temp1];
[time_highest addObject:temp2];
}
}
}*/
//finding the period: time for 1 oscillation in second (remember that it is in second VERY IMPORTANT)
}
return 0;
}
You are comparing objects (NSNumber) instead of their numerical value.
do: if ([acc_x[i] intValue] > [acc_x[i-1] intValue])
instead of if (acc_x[i] > acc_x[i-1])
Related
I am looking for an algorithm to determine if there are at least three consecutive numbers in an array. I have found several and tweaked them a bit, but it does not seem to be working. Below is what I am currently doing. The array is sorted using an NSSortDescriptor prior to the loop.
For example:
in an array [5,6,101,102,103] the three consecutive numbers are [101,102,103]
and the below function should return YES.
int c = [checkArray count];
int a,b = 0;
int cnt = 1;
for (int i = 1; i < c; i++)
{
a = [[checkArray objectAtIndex:i] intValue];
b = [[checkArray objectAtIndex:i-1] intValue] - 1;
if (a == b)
{
cnt++;
if (cnt == 3)
return YES;
} else {
cnt = 1;
}
}
return NO;
This is an alternative approach. I haven't tested it, but you should get the idea.
int c = [checkArray count];
int a,b,c = 0;
a = [[checkArray objectAtIndex:0] intValue];
b = [[checkArray objectAtIndex:1] intValue];
for (int i = 2; i < c; i++)
{
c = [[checkArray objectAtIndex:i] intValue];
if (a+2 == b+1 && b+1 == c)
return YES;
a = b;
b = c;
}
return NO;
It has the additional advantage of being easily optimized.
You should be able to do something like...
for (int i = 1; i < checkArray.count-1; i++)
{
int lower = [checkArray[i-1] intValue] +1;
int mid = [checkArray[i] intValue];
int upper = [checkArray[i+1] intValue] -1;
if (lower == mid && mid == upper) {
return YES;
}
}
return NO;
You only need to check each number once. No need to count anything. Each number you check is the middle of three numbers. If the one before and the one after are one less and one greater respectively then the three numbers are consecutive.
The arrayTwelveLEngth variable isn't working as expected. When I placed a breakpoint on the amount = 1; line above, I hovered over arrayTwelve, and found that it was empty with 0 elements. Immediately after, I then hovered about arrayTwelveLength, expecting to see 0, but instead it seems that the arrayTwelveLength had a value of 1876662112. I don't know how it got that value, and I need to solve that problem. What am I doing wrong?
NSMutableArray *redValues = [NSMutableArray array];
NSMutableArray *arrayTwelve = [NSMutableArray array];
__block int counter = 0;
__block NSInteger u;
NSUInteger redValuesLength = [redValues count];
__block int arrayTwelveLength = 0;
__block float diffForAverage, fps, averageTime, bloodSpeed;
float average;
__block int amount = 1;
__block float totalTwelve, totalThirteen;
__block NSUInteger totalNumberOfFramesInSmallArrays = 0;
__block NSUInteger totalNumberOfFramesNotInSmallArrays;
for (u = (counter + 24); u < (redValuesLength - 24); u++)
{
diffForAverage = average - [redValues[u + 1] floatValue];
float test = [redValues[u] floatValue];
arrayTwelveLength = [arrayTwelve count];
if (diffForAverage > -1 && diffForAverage < 1)
{
totalTwelve += [redValues[u + 1] floatValue];
amount++;
[arrayTwelve addObject:#(test)];
counter++;
}
else
{
if (arrayTwelveLength >= 8)
{
counter++;
break;
}
else
{
[arrayTwelve removeAllObjects];
totalTwelve = [redValues[u + 1] floatValue];
counter++;
amount = 1;
}
}
}
amount = 1; // I added a breakpoint here
totalThirteen = [redValues[u + 1] floatValue];
average = totalThirteen / amount;
if (counter == redValuesLength)
{
totalNumberOfFramesNotInSmallArrays = redValuesLength - totalNumberOfFramesInSmallArrays - 25 - (redValuesLength - counter);
fps = redValuesLength / 30;
averageTime = totalNumberOfFramesNotInSmallArrays / fps;
bloodSpeed = 3 / averageTime;
[_BloodSpeedValue setText:[NSString stringWithFormat:#"%f", bloodSpeed]];
}
if (arrayTwelveLength == NULL)
{
arrayTwelveLength = 0;
}
totalNumberOfFramesInSmallArrays += arrayTwelveLength;
You have problems with unsigned/signed types and with your data set the first for loop should not even enter, because your for loop index variable u (== 24) < (redValuesLength (== 0) - 24) but, because redValuesLength being Unsigned type it wraps around and you get:
(unsigned long)0 - (unsigned long)24 = -24 modulo ULONG_MAX + 1= 18446744073709551592
Also, you are not initialising average before usage.
I wrote a program to sort a randomly generated array of 50 integers from greatest to least. So far it works, but it will occasionally return random zeros at the end of the sorted array. These zeros are not present in the unsorted array, and they do not always appear. Here's my program:
#import <Foundation/Foundation.h>
#interface Number: NSObject
- (void) start;
- (int) getValue;
- (void) counted;
- (void) placeValue: (int) a;
#end
#implementation Number
{
int x;
}
- (void) start
{
x = arc4random_uniform(1000);
if (x == 1)
{
x = x+1;
}
}
- (int) getValue
{
return x;
}
- (void) counted
{
x = 0;
}
- (void) placeValue: (int) a
{
x = a;
}
#end
int main(int argc, const char * argv[])
{
#autoreleasepool
{
NSMutableArray *unsortedArray = [[NSMutableArray alloc] initWithCapacity: 50];
for (int n = 0; n < 50; n++)
{
Number *num = [[Number alloc] init];
[num start];
[unsortedArray addObject: num];
}
for (int n = 0; n < 50; n++)
{
printf("%i, ", [unsortedArray[n] getValue]);
}
printf ("unsorted array.\n\n");
int x = 0;
int y = 1001;
for (int n = 0; n < 50; n++)
{
for (int m = 0; m < 50; m++)
{
if (([unsortedArray[m] getValue] > x) && ([unsortedArray[m] getValue] < y))
{
x = [unsortedArray[m] getValue];
}
}
printf("%i, ", x);
y = x;
x = 0;
}
printf("sorted array.\n");
} return 0;
}
Try this:
- (void)start
{
x = (arc4random_uniform(1000) + 1);
}
You don't want to only be increasing x when you hit 0 or 1, since that will skew the results. arc4random_uniform will return a random number less than 1000 in this case, so 0 -> 999, adding 1 to all values, gives you 1 -> 1000. Adjust your numbers to suit what you need.
There are other issues in your code though. Why create your own Number class? Why create your own sort method? Use NSNumber and NSArray's sort methods.
Here is a much cleaner version:
int main(int argc, const char * argv[])
{
#autoreleasepool
{
NSMutableArray* unsortedArray = [[NSMutableArray alloc] initWithCapacity:50];
for (NSUInteger n = 0; n < 50; ++n) {
[unsortedArray addObject:#(arc4random_uniform(999) + 1)];
}
for (NSUInteger n = 0; n < 50; ++n) {
printf("%li, ", (long)[unsortedArray[n] integerValue]);
}
printf ("unsorted array.\n\n");
NSArray* sortedArray = [unsortedArray sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [obj2 compare:obj1];
}];
for (NSUInteger n = 0; n < 50; ++n) {
printf("%li, ", (long)[sortedArray[n] integerValue]);
}
printf("sorted array.\n");
}
return 0;
}
- (void) start
{
x = arc4random_uniform(1000);
if (x == 0)
x = x + 1;
}
Everyone is focusing on the fact that arc4random_uniform can generate zero as an acceptable value (which is true), but there is another problem: Your sort algorithm is incorrect, as it will only work if the values in the array are unique. But, if you have any duplicate values (and there's no assurances that arc4random_uniform won't generate some duplicates), your algorithm will show only one of those values, and thus, by the time you get to the end, you'll see a bunch of extra zeros.
There are tons of different sorting algorithms, but it's probably easier to just avail yourself of one of the native NSMutableArray sort methods, which gets you out of the weeds of writing your own.
Is there an easy way to transform an array of numbers to an arrays with the numbers in sequence?
NSArray *numbers = #[#1,#2,#5,#3];
// Transformed arrays
//NSArray *numbersInSequence = #[#1,#2,#3];
//NSArray *numbersInSequence2 = #[#5];
EDIT:
I modified the code in Richard's answer to get it to work.
NSArray *arraysBySplittingNumbersInOrder(NSArray *input) {
// sort 'input'
input = [input sortedArrayUsingSelector:#selector(compare:)];
NSMutableArray *results = [NSMutableArray array];
if (input.count) {
int start = 0;
int last = INT_MIN;
for (int i = 0; i < input.count; i++) {
BOOL lastItem = i == input.count - 1;
// The first item of the array
if (i == 0) {
if (lastItem) {
[results addObject:input];
break;
}
last = [input[i] intValue];
continue;
}
int cur = [input[i] intValue];
if (cur != last + 1) {
// pull out the next array
[results addObject:[input subarrayWithRange:NSMakeRange(start, i - start)]];
start = i;
}
// The last item of the array
if (lastItem) {
[results addObject:[input subarrayWithRange:NSMakeRange(start, i - start + 1)]];
}
last = cur;
}
}
return results;
}
Here's a rather simple solution:
NSArray *arraysBySplittingNumbersInOrder(NSArray *input)
{
// sort 'input'
input = [input sortedArrayUsingSelector:#selector(compare:)];
NSMutableArray *results = [NSMutableArray array];
if (input.count)
{
int start = 0;
int last = INT_MIN;
for (int i = 0; i <= input.count; i++)
{
if (i == 0)
{
last = [input[i] intValue];
continue;
}
if (i == input.count)
{
if (i != start + 1)
{
[results addObject:[input subarrayWithRange:NSMakeRange(start, i - start)]];
continue;
}
}
int cur = [input[i] intValue];
if (cur != last + 1)
{
// pull out the next array
[results addObject:[input subarrayWithRange:NSMakeRange(start, i - start)]];
start = i;
}
last = cur;
}
}
return results;
}
int main()
{
NSArray *input = #[ #1, #3, #4, #7, #8, #12, #13, #14 ];
NSLog(#"%#", input);
NSLog(#"%#", arraysBySplittingNumbersInOrder(input));
}
Output:
2012-11-27 07:55:04.609 TestProj[35890:303] (
1,
3,
4,
7,
8,
12,
13,
14
)
2012-11-27 07:55:04.611 TestProj[35890:303] (
(
1
),
(
3,
4
),
(
7,
8
),
(
12,
13,
14
)
)
I don't think there's an easy way to do this; you'll probably have to do at least part of the work yourself.
My suggestion would be to sort the array an then iterate through it, building the sections as you go. Whenever you hit a "jump", i.e. a non-consecutive number, this concludes your current section and starts a new one.
When I profile my code with Instruments, it shows a leak of Malloc 16 bytes from this function (below), but I never used malloc in this function. Is there a place in this function where I should free some resources?
It may look like a lot of code, but there is really only the variables counts and counts2 as possible offenders I think.
+ (int) trimArray: (NSMutableArray*) source above: (short) max andMin: (short) min
{
int counts[6][7];
int counts2[6][7];
for (int i=0;i<=5;i++)
{
for (int ii=0;ii<7;ii++)
{
counts[i][ii] = 0;
counts2[i][ii] = 0;
}
}
int capacity = (int)[source count]/max;
if (capacity <2)
capacity = 2;
NSMutableArray *itemsToRemove = [[NSMutableArray alloc] initWithCapacity:capacity];
int week,dow,count1,count2;
EntryTimeItem *item;
NSEnumerator *e;
e = [source objectEnumerator];
while (item = [e nextObject])
{
week = item.week_number;
dow = item.day_of_the_week;
if (week >=0 && week <6 && dow >=0 && dow <7)
{
counts[week][dow]++;
}
}
e = [source objectEnumerator];
while (item = [e nextObject])
{
week = item.week_number;
dow = item.day_of_the_week;
if (week >= 0 && week < 6 && dow >= 0 && dow < 7)
{
count2 = counts2[week][dow];
count1 = counts[week][dow];
if (count1 > max)
{
if (!count2)
{
item.time = -1;
item.align = NSCenterTextAlignment;
item.label = [NSString stringWithFormat:#"%d entries",count1];
}
else {
// remove this item if it is after the first item which
// was converted to a placeholder for all the items
[itemsToRemove addObject:item];
}
}
counts2[week][dow]++;
}
}
e = [itemsToRemove objectEnumerator];
while (item = [e nextObject])
{
[source removeObject:item];
}
int count_extra_events = 0;
for (int i=0;i<7;i++)
{
int count_events2 = 0;
for (int ii = 0; ii < 6; ii++)
{
int count3 = counts[ii][i];
if (count3 < max && count3 > min)
count_events2 += count3 - min;
}
// store the greatest value found sofar
if (count_events2 > count_extra_events)
{
count_extra_events = count_events2;
}
}
return count_extra_events;
}
The problem appears to stem from the line:
NSMutableArray *itemsToRemove = [[NSMutableArray alloc] initWithCapacity:capacity];
Please check if there is anyway, the resource itemsToRemove can be freed.