I have a question that confused me for a long time. As you know, when we use an if condition in Modelica, that means if the expression is true, then Modelica will do the corresponding equation.
But when i test the following code, I am confused:
model Model134
Real a(start = 0);
equation
if not sample(0, 2) then
a = 1;
else
a = 3;
end if;
end Model134;
I think a will be changed every 2s (start time=0), but when I simulate this model, it dose not change and a is equal to 1 all the time.
Dose anybody know the root cause?
a does change its value, but depending on your simulation tool you might not see it in the plot.
sample(0, 2) creates a time event every 2 seconds. The return value of sample() is only true during the event. So the value of a changes, but after the event it immediately changes back.
In this answer to a similar question, it is mentioned that Dymola stores the value before and after the event in result file. Intermediate values are skipped for efficiency reasons (there can be many for every event, which would bloat up your result file). Hence you can not plot this change in Dymola. For OpenModelica see the answer by
Akhil Nandan.
To proof that a really does change its value you can use this code for example:
model Model134
import Modelica.Utilities.Streams.print;
Real a;
equation
if sample(0, 2) then
a = 1;
else
a = 0;
end if;
when a > 0.5 then
print("a is " + String(a) + " at t=" + String(time) + "s");
end when;
annotation (experiment(StopTime=10));
end Model134;
You should see something like this in the simulation log:
a is 1 at t=2s
a is 1 at t=4s
a is 1 at t=6s
a is 1 at t=8s
a is 1 at t=10s
This is the plot simulated when trying your above code in OpenModelica with settings shown in the second figure.
A time event is triggered when sample(startTime,interval) evaluates true at every multiple of 2 seconds and based on your code logic this should activate else
block and assign value of variable a to be 3.
Related
Thanks in advance for helping with this.
I have an issue where this I need the following formula to calculate this- i would advise seeing the picture in the link to fully understand the question (as I'm probably not going to explain myself!);
Calculating Risk Score
Condition 1: If Blood Result is less <=9 or Score <=6 or Tumour Size = <5mm show as text value Low
Condition 2 : If Blood Result 10-20 or Score = 7 or Tumour Size 5mm-9mm show as text value Medium
Condition 3: If Blood Result >=20 or Score = 8 or Tumour Size >=10mm show as text value High
The issue I am having is that any person can have a value from any of the condition, but I need to display the overriding value.
Example:
Blood Result = 5 (condition 1)
Score = 7 (condition 2)
Tumour Size = 10mm (condition 3)
SHOW VALUE: HIGH.
The problemn i'm having is that when I'm doing IF statements, as condition 1 of blood result is True, its always displaying Low without looking at the other values which could overwrite it.
I have only tried nested IF statements with AND OR in them, but no luck.
See examples of values
you can do one thing for that type condition
store your message in one variable, for example, var = msg
if condition 1 true assign msg = "Low"
if condition 2 true assign msg = "Medium"
if condition 3 true assign msg = "High"
after checking all conditions print your message.
I hope this will help you
The thinkscript if statement fails to branch as expected in some cases. The following test case can be used to reproduce this bug / defect.
It is shared via Grid containing chart and script
To cut the long story short, a possible workaround in some cases is to use the if-expression which is a function, which may be slower, potentially leading to Script execution timeout in scans.
This fairly nasty bug in thinkscript prevents me from writing some scans and studies the way I need to.
Following is some sample code that shows the problem on a chart.
input price = close;
input smoothPeriods = 20;
def output = Average(price, smoothPeriods);
# Get the current offset from the right edge from BarNumber()
# BarNumber(): The current bar number. On a chart, we can see that the number increases
# from left 1 to number of bars e.g. 140 at the right edge.
def barNumber = BarNumber();
def barCount = HighestAll(barNumber);
# rightOffset: 0 at the right edge, i.e. at the rightmost bar,
# increasing from right to left.
def rightOffset = barCount - barNumber;
# Prepare a lookup table:
def lookup;
if (barNumber == 1) {
lookup = -1;
} else {
lookup = 53;
}
# This script gets the minimum value from data in the offset range between startIndex
# and endIndex. It serves as a functional but not direct replacement for the
# GetMinValueOffset function where a dynamic range is required. Expect it to be slow.
script getMinValueBetween {
input data = low;
input startIndex = 0;
input endIndex = 0;
plot minValue = fold index = startIndex to endIndex with minRunning = Double.POSITIVE_INFINITY do Min(GetValue(data, index), minRunning);
}
# Call this only once at the last bar.
script buildValue {
input lookup = close;
input offsetLast = 0;
# Do an indirect lookup
def lookupPosn = 23;
def indirectLookupPosn = GetValue(lookup, lookupPosn);
# lowAtIndirectLookupPosn is assigned incorrectly. The if statement APPEARS to be executed
# as if indirectLookupPosn was 0 but indirectLookupPosn is NOT 0 so the condition
# for the first branch should be met!
def lowAtIndirectLookupPosn;
if (indirectLookupPosn > offsetLast) {
lowAtIndirectLookupPosn = getMinValueBetween(low, offsetLast, indirectLookupPosn);
} else {
lowAtIndirectLookupPosn = close[offsetLast];
}
plot testResult = lowAtIndirectLookupPosn;
}
plot debugLower;
if (rightOffset == 0) {
debugLower = buildValue(lookup);
} else {
debugLower = 0;
}
declare lower;
To prepare the chart for the stock ADT, please set custom time frame:
10/09/18 to 10/09/19, aggregation period 1 day.
The aim of the script is to find the low value of 4.25 on 08/14/2019.
I DO know that there are various methods to do this in thinkscript such as GetMinValueOffset().
Let us please not discuss alternative methods of achieving the objective to find the low, alternatives for the attached script.
Because I am not asking for help achieving the objective. I am reporting a bug, and I want to know what goes wrong and perhaps how to fix it. In other words, finding the low here is just an example to make the script easier to follow. It could be anything else that one wants a script to compute.
Please let me describe the script.
First it does some smoothing with a moving average. The result is:
def output;
Then the script defines the distance from the right edge so we can work with offsets:
def rightOffset;
Then the script builds a lookup table:
def lookup;
script getMinValueBetween {} is a little function that finds the low between two offset positions, in a dynamic way. It is needed because GetMinValueOffset() does not accept dynamic parameters.
Then we have script buildValue {}
This is where the error occurs. This script is executed at the right edge.
buildValue {} does an indirect lookup as follows:
First it goes into lookup where it finds the value 53 at lookupPosn = 23.
With 53, if finds the low between offset 53 and 0, by calling the script function getMinValueBetween().
It stores the value in def lowAtIndirectLookupPosn;
As you can see, this is very simple indeed - only 38 lines of code!
The problem is, that lowAtIndirectLookupPosn contains the wrong value, as if the wrong branch of the if statement was executed.
plot testResult should put out the low 4.25. Instead it puts out close[offsetLast] which is 6.26.
Quite honestly, this is a disaster because it is impossible to predict which of any if statement in your program will fail or not.
In a limited number of cases, the if-expression can be used instead of the if statement. However the if-expression covers only a subset of use cases and it may execute with lower performance in scans. More importantly,
it defeats the purpose of the if statement in an important case because it supports conditional assignment but not conditional execution. In other words, it executes both branches before assigning one of two values.
Very simple. Cell A1 has an image in it, which I supply through Insert:Picture:From File...
Now I want Cell A3 to automatically show the same picture. I simply can't find a way-- certainly the "=" doesn't work. At this point, I don't care if the images are "links" or embedded, I just want it to work. Can it? Thx.
Edit, 09-01-17, based on Jim K's idea, here's macro code I have installed:
REM ***** BASIC *****
Private oListener as Object
Private cellA1 as Object
Sub AddListener
Dim Doc, Sheet, Cell as Object
Doc = ThisComponent
Sheet = Doc.Sheets.getByName("Sheet1")
cellA1 = Sheet.getCellrangeByName("A1")
'create a listener
oListener = createUnoListener("Modify_","com.sun.star.util.XModifyListener")
'register the listener
cellA1.addModifyListener(oListener)
End Sub
Sub Modify_disposing(oEv)
End Sub
Sub RmvListener
cellA1.removeModifyListener(oListener)
End Sub
' macro jumps here when oListener detects modification of Sheet
Sub Modify_modified(oEv)
Doc = ThisComponent
Sheet = Doc.Sheets.getByIndex(0)
originCell = Sheet.getCellByPosition(0,0)
originValue = originCell.Value
if originValue then
print "originValue is " & originValue
else
print "originValue zero"
end if
End Sub
The problem, ironically, is that it works. It works for integers and {non-value}, I mean an empty cell.
So any integer not zero prints TRUE, zero prints FALSE, and empty cell prints FALSE.
But that's where it quits working-- any kind of string "asdf" also returns FALSE.
Maybe that could be fixed, but there's something a lot worse: When I paste an image in the cell, or use the Insert/Image/From File... menu, or Cut an existing image... Nothing happens! The Sheet Modified business does not trigger the expected routine.
Any hope? Thx.
As you discovered, the solution in my comment does not work, because the Content changed event will not trigger when images are added. I looked into other events as well, but they did not work either.
So instead, we can set up a function that runs periodically. Each time it runs, it checks the count of images, and if any have been added or removed, it calls update_copied_images() below, which currently simply reports the value of cell A1, as in your code.
As explained here, I have not gotten a timer loop to work in Basic without crashing, so we can use Python instead (a better language, so this is not a drawback in my opinion).
import time
from threading import Thread
import uno
COLUMN_A, COLUMN_B, COLUMN_C = 0, 1, 2
FIRST_ROW = 0
def start_counting_images(action_event=None):
t = Thread(target = keep_counting_images)
t.start()
def keep_counting_images():
oDoc = XSCRIPTCONTEXT.getDocument()
oSheet = oDoc.getSheets().getByIndex(0)
oDrawPage = oSheet.getDrawPage()
messageCell = oSheet.getCellByPosition(COLUMN_C, FIRST_ROW)
messageCell.setString("Starting...")
prevCount = -1
while hasattr(oDoc, 'calculateAll'): # keep going until document is closed
count = oDrawPage.Count
if prevCount == -1 or prevCount != count:
prevCount = count
messageCell.setString("Number of Images: " + str(prevCount))
update_copied_images(oSheet)
time.sleep(1)
def update_copied_images(oSheet):
originCell = oSheet.getCellByPosition(COLUMN_A, FIRST_ROW)
originString = originCell.getString()
messageCell = oSheet.getCellByPosition(COLUMN_B, FIRST_ROW)
if len(originString):
messageCell.setString("originString '" + originString + "'")
else:
messageCell.setString("originString length is zero")
g_exportedScripts = start_counting_images,
To run, go to Tools -> Macros -> Run Macro, find the .py file under My Macros where you put this code, and run start_counting_images.
I have been trying to implement the Stupid Backoff language model (the description is available here, though I believe the details are not relevant to the question).
The thing is, the code's working and producing the result that is expected, but works slower than I expected. I figured out the part that was slowing down everything is here (and NOT in the training part):
def compute_score(self, sentence):
length = len(sentence)
assert length <= self.n
if length == 1:
word = tuple(sentence)
return float(self.ngrams[length][word]) / self.total_words
else:
words = tuple(sentence[::-1])
count = self.ngrams[length][words]
if count == 0:
return self.alpha * self.compute_score(sentence[1:])
else:
return float(count) / self.ngrams[length - 1][words[:-1]]
def score(self, sentence):
""" Takes a list of strings as argument and returns the log-probability of the
sentence using your language model. Use whatever data you computed in train() here.
"""
output = 0.0
length = len(sentence)
for idx in range(length):
if idx < self.n - 1:
current_score = self.compute_score(sentence[:idx+1])
else:
current_score = self.compute_score(sentence[idx-self.n+1:idx+1])
output += math.log(current_score)
return output
self.ngrams is a nested dictionary that has n entries. Each of these entries is a dictionary of form (word_i, word_i-1, word_i-2.... word_i-n) : the count of this combination.
self.alpha is a constant that defines the penalty for going n-1.
self.n is the maximum length of that tuple that the program is looking for in the dictionary self.ngrams. It is set to 3 (though setting it to 2 or even 1 doesn't anything). It's weird because the Unigram and Bigram models work just fine in fractions of a second.
The answer that I am looking for is not a refactored version of my own code, but rather a tip which part of it is the most computationally expensive (so that I could figure out myself how to rewrite it and get the most educational profit from solving this problem).
Please, be patient, I am but a beginner (two months into the world of programming). Thanks.
UPD:
I timed the running time with the same data using time.time():
Unigram = 1.9
Bigram = 3.2
Stupid Backoff (n=2) = 15.3
Stupid Backoff (n=3) = 21.6
(It's on some bigger data than originally because of time.time's bad precision.)
If the sentence is very long, most of the code that's actually running is here:
def score(self, sentence):
for idx in range(len(sentence)): # should use xrange in Python 2!
self.compute_score(sentence[idx-self.n+1:idx+1])
def compute_score(self, sentence):
words = tuple(sentence[::-1])
count = self.ngrams[len(sentence)][words]
if count == 0:
self.compute_score(sentence[1:])
else:
self.ngrams[len(sentence) - 1][words[:-1]]
That's not meant to be working code--it just removes the unimportant parts.
The flow in the critical path is therefore:
For each word in the sentence:
Call compute_score() on that word plus the following 2. This creates a new list of length 3. You could avoid that with itertools.islice().
Construct a 3-tuple with the words reversed. This creates a new tuple. You could avoid that by passing the -1 step argument when making the slice outside this function.
Look up in self.ngrams, a nested dict, with the first key being a number (might be faster if this level were a list; there are only three keys anyway?), and the second being the tuple just created.
Recurse with the first word removed, i.e. make a new tuple (sentence[2], sentence[1]), or
Do another lookup in self.ngrams, implicitly creating another new tuple (words[:-1]).
In summary, I think the biggest problem you have is the repeated and nested creation and destruction of lists and tuples.
Folks,
So I've been working on a little GUI using Tkinter for a capstone project, and given the circumstances, I've only been programming for about two weeks before I was thrown into this, so I'm still a newbie.
My issue today is that I cannot manage to get my checkbutton dictionary to update values; the output for my checkbutton is always 0 or False. The code is as follows:
...
datatype= {'Joint Angle' : 0,
'Joint Acceleration' : 0,
'Ground Reaction Force' : 0,
'Muscle Activation' : 0
}
for measure in datatype:
datatype[measure] = IntVar()
dt_cb = Checkbutton(root, text=measure,
variable=datatype[measure],command = enable_location_state)
dt_cb.grid(column=0, sticky='W', padx=20)
dt1 = datatype['Joint Angle'].get()
dt2 = datatype['Joint Acceleration'].get()
dt3 = datatype['Ground Reaction Force'].get()
dt4 = datatype['Muscle Activation'].get()
...
So I tried periodically printing values throughout the code and I continued to get 0 as soon as I booted the GUI, and after that, no matter what I clicked, the numbers did not update. I read that I should try BooleanVar() and StringVar() instead, but neither of those worked. The code is based off of another bit of code I found somewhere on stackoverflow, though I cannot remember exactly where.
I tried making it a list rather than a dictionary in order to overcome my problem because I was successful with lists previously, but the list created only a single checkbutton for all of those and I was unable to differentiate what is what.
The command enable_location_state configures other checkbuttons, and is as follows:
def enable_location_state():
if dt1 == 1 or dt2 == 1:
ja_cb.configure(state=ACTIVE)
if dt3 == 1:
grf_cb.configure(state=ACTIVE)
if dt4 == 1:
emg_cb.configure(state=ACTIVE)
Your problem is that you are getting the values of the IntVar only once: at the same moment you create your buttons. Move your .get() statements to the beginning of the enable_location_state() function. That way, every time your checkbutton is clicked, the function will check on (i.e., .get()) the value of the IntVar.