Basic Question/Help

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Summary:

Help with basic coding for program that displays mean, median, and sample standard deviation.

Basic Question/Help

Eric (guest) 08 May 2015 01:57

I need to write a program that achieves the following:

A user will input the average wheat yield in pounds per acre for five different countries. The 5 variables the user inputs are then displayed in three ways: mean, median, and sample standard deviation.

Here are 2 example of how have been trying to write the code:

Clrhome
Input "India", L1
Input "U.S.", L1
Disp mean(L1

and….

Clrhome
input "India", A
A->L1
Input "U.S.", B
B->L1
Disp mean(L1

Neither method is working. I am a very new to coding and therefore I know my question is simple/dumb. So I apologize for that. Any help would be greatly appreciated.

Best

Re: Basic Question/Help

Michael2_3B 08 May 2015 02:21

are you getting a data type error? If you are, that's because you can't store A into L1. Also, you cannot use the Input command with L1. Also, you would want to add to L1 for each input, otherwise you are just overwriting it each time.

Last edited on 08 May 2015 02:44 by Michael2_3B Show more

Re: Basic Question/Help

lirtosiast 08 May 2015 02:29

A list input in the format you described will not work. The list will be saved to ∟A, but the parser will still try to store the real variable A to L1, giving a syntax error.

Re: Basic Question/Help

Michael2_3B 08 May 2015 02:46

Oh, oops. Obvious mistake :) If you use a string like Eric is saying, that would work.

Eric (guest) 08 May 2015 02:32

Thanks for responding Michael. What if I use String. Would that work?

Michael2_3B 08 May 2015 02:42

Yes. If you do

Input "India:",Str1
expr("{"+Str1

That will give you a list format. Then you can use that with the commands mean(), median(), and stdDev().

EDIT: If you were to use this, the user should enter data like this: 5,1,68,2,92,5

Last edited on 08 May 2015 02:59 by Michael2_3B Show more

Eric (guest) 08 May 2015 02:46

ah. Let me give that a try.

Eric (guest) 08 May 2015 02:45

This doesn't seem to work either. I am getting a syntax error

ClrHome
Input "India",Str2
Str2→L₁
Disp mean(L₁

Michael2_3B 08 May 2015 02:49

You cannot store a string of characters into a list of numbers. Those are two completely different data types. My code should work though :)

Eric (guest) 08 May 2015 03:03

I still don't understand how to get the value to return after it's inputted and stored. Sorry, like I said, I"m "beginner."

Michael2_3B 08 May 2015 03:20

You would probably want to use Disp [link] for this one. So, you could do

Input "India:",Str1
expr("{"+Str1->L1
Disp mean(L1
Disp median(L1
Disp stdDev(L1

and that would be for each one. However, if you are wanting to do it for everything, you could do

"{->Str1   //opening list bracket is stored in a string(this is a comment btw, so this is not part of the code)
Input "India:",Str2
Str1+Str2->Str1    //this string should now look like {N,N,N,N,(etc.)} (N being the numbers)
Input "U.S.",Str2
Str1+Str2->Str1    //add the new inputted string to the previous string

//etc.

expr(Str1   //the list for everything is stored in Ans automatically, without the need of "->"
Disp mean(Ans),median(Ans),stdDev(Ans   //Disp can be separated by commas, rather than doing "Disp" over and over again.

Wheat per acre

Trenly 08 May 2015 04:25

Or do:

Delvar L1SetUpEditor L1 //don't have the ability to do subscripts right now
Input "US:",L1(1)
Input "India:",L1(2)
Input "China:",L1(3)
Input "UK:",L1(4)
//repeat for each country
Disp mean(L1),median(L1),stdDev(L1)

Or:

Input "US:",A
//all your countries here
{A,B,...}->L1
Disp mean(L1),median(L1),stdDev(L1)

---

Michael is right. The best code would probably be:

Input "Data:", Str1
expr("{"+ Str1)->L1
Disp mean(L1),median(L1),stdDev(L1)

**This is the code I recommend**

Or:

Input "Data:", Str1
Disp mean(expr("{"+ Str1)),median(expr("{"+ Str1)),stdDev(expr("{"+ Str1))

Be sure to pay attention to commas, quotes, and parentheses.

Re: Wheat per acre

Michael2_3B 08 May 2015 04:30

ehh, using Ans would be the best and most optimized way to do it. You shouldn't repeat the expr() thing. just do

Input "Data:",Str1
expr("{"+Str1
Disp mean(Ans),median(Ans),stdDev(Ans

Re: Basic Question/Help

jonbush 08 May 2015 04:35

In this case, it may be simpler to just use the 1-Var Stats from the Stat>Calc menu. This command will calculate all of the summary statistics for a list. This way you can also use the list editor (Stat>Edit…) to enter the values for each country into different lists, and run 1-Var Stats on each list individually.

Eric (guest) 08 May 2015 04:56

Thank you all. Very helpful information. One question though. Why is this method the best:

Input "Data:", Str1
expr("{"+ Str1)->L1
Disp mean(L1),median(L1),stdDev(L1)

and not this:

Input "US:",L1(1)
Input "India:",L1(2)
Input "China:",L1(3)
Input "UK:",L1(4)
//repeat for each country
Disp mean(L1),median(L1),stdDev(L1)

I only ask because I thought Strings were mainly used for alpha values and not numbers.

jonbush 08 May 2015 05:01

The first method is best mainly because the second option does not work. Since you are only finding the mean, median and standard deviation for one list of five values, the first method is also much simpler.

Jonbush

Trenly 08 May 2015 05:14

Why would the second option not work?

Re: Jonbush

Michael2_3B 08 May 2015 12:38

Syntax error, because unfortunately, you can't store to a list element directly from an Input command.

Re: Jonbush

Trenly 08 May 2015 12:43

Ah. I didn't have a calculator with me at the time.

Best

Trenly 08 May 2015 05:13

That is a very good question.

Strings can be used in many ways. One use is to, as you mentioned, store Alpha values. Another function of strings is the ability to store expressions. So if you had a string containing "1+2", Str1 would return 1+2 while expr(Str1) returns 3. This allows for very complex equations, if you know how to work the commands correctly.

---

By using the characteristics of adding strings, we can turn data in the form:

1,5,3,n...

Into a list by putting a bracket out front.

This type of input allows for any amount of data entries to be input, without having the calculator ask for how many there are, and then ask each individually.

---

Size is also a big factor, along with speed. The use of strings allows for a great reduction in size and an increase in speed. Rather than having to look through each element of a list, the calculator can just recall the string. Also, you never have to worry about existing variables in the list of the domain is larger than what you need, it will always contain just the data you enter. A smaller program also means more ram, which means more processing speed. Some of the best codes I have seen were written with the use of strings.

---

If you have anymore questions, feel free to ask! Also, you may want to consider becoming a member! It will allow others to see if you offer valuable advice, and allows you to use code blocks, and post links after a little while! Hope this helps!

Michael2_3B 08 May 2015 12:38

Oh, for some reason I thought you were wanting to put in multiple values for each country, but I guess not. So yes, you could do the second option, but not how you have it. You will get a Syntax error if you try to store a value directly to a list element from an Input command. However, you can do something like you have below, where you do A,B,C etc. and then do {A,B,C,etc.} and then mean(Ans),median(Ans),stdDev(Ans).

Strings can contain any token/character you want, however you can not put in characters like → or "

Eric (guest) 08 May 2015 05:17

I honestly didn't understand half of what you guys were telling me lol. I ended up just doing this and it worked out:

Input "India:",A
Input "Is:",B
Input "it:",C
Input "me:",D
Input "do:",E
{A,B,C,D,E}→L₁
Disp mean(L₁),median(L₁),stdDev(L₁)

Trenly 08 May 2015 05:29

That works. But I still recommend the code below if you are looking for the shortest and the fastest

Input "Data:", Str1
expr("{"+ Str1)->L1
Disp mean(L1),median(L1),stdDev(L1)

Eric (guest) 08 May 2015 05:40

I'd love to use that code. However, I don't quite understand it. Here is how I interpreted it (i'm sure it's not even close):

Input "India:",Str1
expr("{"+Str1->L1
Input "U.S.:",Str2
Input "China",Str3
Input "Russia",Str4
Input "Canada",Str5
Str1+Str2+Str3+Str4+Str5->Str1
expr(Str1
Disp mean(Ans), median(Ans),stdDev(Ans)

In the second line above, is the "+" sign used before Str1 to indicate additional strings will be added to it?

Okay

Trenly 08 May 2015 05:59

So. the code takes all the inputs as one. The input on the screen would look like: 5,6,2,4 This eliminates the need for multiple "Input" commands.
The plus sign is taking the string 5,6,2,4 and adding "{" to the front of it, turning it into {5,6,2,4
Then, once it is in that format, the calculator can treat the expression as a list. By storing that list, we can then perform the three operations on the list, and display their answers.
So this is what the homescreen of the program would look like with each code: (yes, I realize these aren't the countries you will be using)

---

Your current code:

India:5
China:6
U.S:2
UK:4
              17/4
                 4
             2.634

---

The three line code I gave you:

Data:5,6,2,4
                  17/4
                     4
                 2.634

---

I don't have my calculator in front of me, so the numbers might not be accurate, but I think you'll get the idea.

Last edited on 08 May 2015 06:02 by Trenly Show more

Eric (guest) 08 May 2015 05:54

Edit from above post:
I'd love to use that code. However, I don't quite understand it. Here is how I interpreted it (i'm sure it's not even close):

Input "India:",Str1
expr("{"+Str1->L1
Input "U.S.:",Str2
Input "China",Str3
Input "Russia",Str4
Input "Canada",Str5
Str1+Str2+Str3+Str4+Str5->Str1
Disp mean(Ans), median(Ans),stdDev(Ans)

In the second line above, is the "+" sign used before Str1 to indicate additional strings will be added to it?

Trenly 08 May 2015 06:00

See above :)

Here is what the command does:

Takes the input (let's use example from above) 5,6,2,4
Turns it into {5,6,2,4 by using "{"+Str1
Returns it as a list using expr(
Saves it using -> L1
Displays the data you need

Last edited on 08 May 2015 06:06 by Trenly Show more

Eric (guest) 08 May 2015 06:18

That's fine and I see that it erases multiple steps (it's more effecient). But for the purpose of my program I need the display to look this this for the user:

India: 5
China: 6
U.s.: 3
Canada: 4
Russia: 3

Mean = ans
Medium = ans
Standard Deviation = ans

If I do it like that, if I'm understanding you correctly, it will look like this:

Data: 5,6,3,4,3

Mean = ans
Medium = ans
SD = ans

Trenly 08 May 2015 11:46

Yeah, that's what I said earlier

Timtech 10 May 2015 00:54

To do it like you want to, try this:

Input "India: ",A
Input "China: ",B
Input "US: ",C
Input "Canada: ",D
Input "Russia: ",E
{A,B,C,D,E
Disp mean(L1),median(L1
stdDev(L1

jonbush 10 May 2015 03:10

The list either needs to be stored to L1, or the last statements need to be evaluated of Ans:

Input "India: ",A
Input "China: ",B
Input "US: ",C
Input "Canada: ",D
Input "Russia: ",E
{A,B,C,D,E
ClrHome
Disp mean(Ans),median(Ans),stdDev(Ans
Output(1,1,"ẋ=
Output(2,1,"Med=
Output(3,1,"Sx=
Pause

The x̄ (x-bar for average) and Sx (for standard deviation) characters are located in Vars>Statistics…
The Med character is at Vars>Statistics>PTS>8