Related
I'm having problem returning spesific amount of decimal numbers from this function, i would like it to get that info from "dec" argument, but i'm stuck with this right now.
Edit: Made it work with the edited version bellow but isn't there a better way?
local function remove_decimal(t, dec)
if type(dec) == "number" then
for key, num in pairs(type(t) == "table" and t or {}) do
if type(num) == "number" then
local num_to_string = tostring(num)
local mod, d = math.modf(num)
-- find only decimal numbers
local num_dec = num_to_string:sub(#tostring(mod) + (mod == 0 and num < 0 and 3 or 2))
if dec <= #num_dec then
-- return amount of deciamls in the num by dec
local r = d < 0 and "-0." or "0."
local r2 = r .. num_dec:sub(1, dec)
t[key] = mod + tonumber(r2)
end
end
end
end
return t
end
By passing the function bellow i want a result like this:
result[1] > 0.12
result[2] > -0.12
result[3] > 123.45
result[4] > -1.23
local result = remove_decimal({0.123, -0.123, 123.456, -1.234}, 2)
print(result[1])
print(result[2])
print(result[3])
print(result[4])
I tried this but it seems to only work with one integer numbers and if number is 12.34 instead of 1.34 e.g, the decimal place will be removed and become 12.3. Using other methods
local d = dec + (num < 0 and 2 or 1)
local r = tonumber(num_to_string:sub(1, -#num_to_string - d)) or 0
A good approach is to find the position of the decimal point (the dot, .) and then extract a substring starting from the first character to the dot's position plus how many digits you want:
local function truncate(number, dec)
local strnum = tostring(number)
local i, j = string.find(strnum, '%.')
if not i then
return number
end
local strtrn = string.sub(strnum, 1, i+dec)
return tonumber(strtrn)
end
Call it like this:
print(truncate(123.456, 2))
print(truncate(1234567, 2))
123.45
1234567
To bulk-truncate a set of numbers:
local function truncate_all(t, dec)
for key, value in pairs(t) do
t[key] = truncate(t[key], dec)
end
return t
end
Usage:
local result = truncate_all({0.123, -0.123, 123.456, -1.234}, 2)
for key, value in pairs(result) do
print(key, value)
end
1 0.12
2 -0.12
3 123.45
4 -1.23
One could use the function string.format which is similar to the printf functions from C language. If one use the format "%.2f" the resulting string will contain 2 decimals, if one use "%.3f" the resulting string will be contain 3 decimals, etc. The idea is to dynamically create the format "%.XXXf" corresponding to the number of decimal needed by the function. Then call the function string.format with the newly created format string to generate the string "123.XXX". The last step would be to convert back the string to a number with the function tonumber.
Note that if one want the special character % to be preserved when string.format is called, you need to write %%.
function KeepDecimals (Number, DecimalCount)
local FloatFormat = string.format("%%.%df", DecimalCount)
local String = string.format(FloatFormat, Number)
return tonumber(String)
end
The behavior seems close to what the OP is looking for:
for Count = 1, 5 do
print(KeepDecimals(1.123456789, Count))
end
This code should print the following:
1.1
1.12
1.123
1.1235
1.12346
Regarding the initial code, it's quite straight-forward to integrate the provided solution. Note that I renamed the function to keep_decimal because in my understanding, the function will keep the requested number of decimals, and discard the rest.
function keep_decimal (Table, Count)
local NewTable = {}
local NewIndex = 1
for Index = 1, #Table do
NewTable[NewIndex] = KeepDecimal(Table[Index], Count)
NewIndex = NewIndex + 1
end
return NewTable
end
Obviously, the code could be tested easily, simply by copy and pasting into a Lua interpreter.
Result = keep_decimal({0.123, -0.123, 123.456, -1.234}, 2)
for Index = 1, #Result do
print(Result[Index])
end
This should print the following:
0.12
-0.12
123.46
-1.23
Edit due to the clarification of the need of truncate:
function Truncate (Number, Digits)
local Divider = Digits * 10
local TruncatedValue = math.floor(Number * Divider) / Divider
return TruncatedValue
end
On my computer, the code is working as expected:
> Truncate(123.456, 2)
123.45
I have one program downloaded from internet and need to get each digit printed out from a three digit number. For example:
Input: 123
Expected Output:
1
2
3
I have 598
Need to Get:
5
9
8
I try using this formula but the problem is when number is with decimal function failed:
FIRST_DIGIT = (number mod 1000) / 100
SECOND_DIGIT = (number mod 100) / 10
THIRD_DIGIT = (number mod 10)
Where number is the above example so here is calulation:
FIRST_DIGIT = (598 mod 1000) / 100 = 5,98 <== FAILED...i need to get 5 but my program shows 0 because i have decimal point
SECOND_DIGIT = (598 mod 100) / 10 = 9,8 <== FAILED...i need to get 9 but my program shows 0 because i have decimal point
THIRD_DIGIT = (598 mod 10) = 8 <== CORRECT...i get from program output number 8 and this digit is correct.
So my question is is there sample or more efficient code that get each digit from number without decimal point? I don't want to use round to round nearest number because sometime it fill failed if number is larger that .5.
Thanks
The simplest solution is to use integer division (\) instead of floating point division (/).
If you replace each one of your examples with the backslash (\) instead of forward slash (/) they will return integer values.
FIRST_DIGIT = (598 mod 1000) \ 100 = 5
SECOND_DIGIT = (598 mod 100) \ 10 = 9
THIRD_DIGIT = (598 mod 10) = 8
You don't have to do any fancy integer calculations as long as you pull it apart from a string:
INPUT X
X$ = STR$(X)
FOR Z = 1 TO LEN(X$)
PRINT MID$(X$, Z, 1)
NEXT
Then, for example, you could act upon each string element:
INPUT X
X$ = STR$(X)
FOR Z = 1 TO LEN(X$)
Q = VAL(MID$(X$, Z, 1))
N = N + 1
PRINT "Digit"; N; " equals"; Q
NEXT
Additionally, you could tear apart the string character by character:
INPUT X
X$ = STR$(X)
FOR Z = 1 TO LEN(X$)
SELECT CASE MID$(X$, Z, 1)
CASE " ", ".", "+", "-", "E", "D"
' special char
CASE ELSE
Q = VAL(MID$(X$, Z, 1))
N = N + 1
PRINT "Digit"; N; " equals"; Q
END SELECT
NEXT
I'm no expert in Basic but looks like you have to convert floating point number to Integer. A quick google search told me that you have to use Int(floating_point_number) to convert float to integer.
So
Int((number mod 100)/ 10)
should probably the one you are looking for.
And, finally, all string elements could be parsed:
INPUT X
X$ = STR$(X)
PRINT X$
FOR Z = 1 TO LEN(X$)
SELECT CASE MID$(X$, Z, 1)
CASE " "
' nul
CASE "E", "D"
Exponent = -1
CASE "."
Decimal = -1
CASE "+"
UnaryPlus = -1
CASE "-"
UnaryNegative = -1
CASE ELSE
Q = VAL(MID$(X$, Z, 1))
N = N + 1
PRINT "Digit"; N; " equals"; Q
END SELECT
NEXT
IF Exponent THEN PRINT "There was an exponent."
IF Decimal THEN PRINT "There was a decimal."
IF UnaryPlus THEN PRINT "There was a plus sign."
IF UnaryNegative THEN PRINT "There was a negative sign."
Hello experienced pythoners.
The goal is simply to read in my own files which have the following format, and to then apply mathematical operations to these values and polynomials. The files have the following format:
m1:=10:
m2:=30:
Z1:=1:
Z2:=-1:
...
Some very similar variables, next come the laguerre polynomials
...
F:= (12.58295)*L(0,x)*L(1,y)*L(6,z) + (30.19372)*L(0,x)*L(2,y)*L(2,z) - ...:
Where L stands for a laguerre polynomial and takes two arguments.
I have written a procedure in Python which splits apart each line into a left and right hand side split using the "=" character as a divider. The format of these files is always the same, but the number of laguerre polynomials in F can vary.
import re
linestring = open("file.txt", "r").read()
linestring = re.sub("\n\n","\n",str(linestring))
linestring = re.sub(",\n",",",linestring)
linestring = re.sub("\\+\n","+",linestring)
linestring = re.sub(":=\n",":=",linestring)
linestring = re.sub(":\n","\n",linestring)
linestring = re.sub(":","",linestring)
LINES = linestring.split("\n")
for LINE in LINES:
LINE = re.sub(" ","",LINE)
print "LINE=", LINE
if len(LINE) <=0:
next
PAIR = LINE.split("=")
print "PAIR=", PAIR
LHS = PAIR[0]
RHS = PAIR[1]
print "LHS=", LHS
print "RHS=", RHS
The first re.sub block just deals with formatting the file and discarding characters that python will not be able to process; then a loop is performed to print 4 things, LINE, PAIR, LHS and RHS, and it does this nicely. using the example file from above the procedure will print the following:
LINE= m1=1
PAIR= ['m1', '1']
LHS= m1
RHS= 1
LINE= m2=1
PAIR= ['m2', '1']
LHS= m2
RHS= 1
LINE= Z1=-1
PAIR= ['Z1', '-1']
LHS= Z1
RHS= -1
LINE= Z2=-1
PAIR= ['Z2', '-1']
LHS= Z2
RHS= -1
LINE= F= 12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)
PAIR=['F', '12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)']
LHS= F
RHS= 12.5*L(0,x)L(1,y) + 30*L(0,x)L(2,y)L(2,z)
My question is what is the next best step to process this output and use it in a mathematical script, especially assigning the L to mean a laguerre polynomial? I tried putting the LHS and RHS into a dictionary, but found it troublesome to put F in it due to the laguerre polynomials.
Any ideas are welcome. Perhaps I am overcomplicating this and there is a much simpler way to parse this file.
Many thanks in advance
Your parsing algorithm doesn't seem to work correctly, as the RHS of your variables dont produce the expected result.
Also the first re.sub block where you want to format the file seems overly complicated. Assuming every statement in your input file is terminated by a colon, you could get rid of all whitespace and newlines and seperate the statements using the following code:
linestring = open('file.txt','r').read()
strippedstring = linestring.replace('\n','').replace(' ','')
statements = re.split(':(?!=)',strippedstring)[:-1]
Then you iterate over the statements and split each one in LHS and RHS:
for st in statements:
lhs,rhs = re.split(':=',st)
print 'lhs=',lhs
print 'rhs=',rhs
In the next step, try to distinguish normal float variables and polynomials:
#evaluate rhs
try:
#interpret as numeric constant
f = float(rhs)
print " ",f
except ValueError:
#interpret as laguerre-polynomial
summands = re.split('\+', re.sub('-','+-',rhs))
for s in summands:
m = re.match("^(?P<factor>-?[0-9]*(\.[0-9]*)?)(?P<poly>(\*?L\([0-9]+,[a-z]\))*)", s)
if not m:
print ' polynomial misformatted'
continue
f = m.group('factor')
print ' factor: ',f
p = m.group('poly')
for l in re.finditer("L\((?P<a>[0-9]+),(?P<b>[a-z])\)",p):
print ' poly: L(%s,%s)' % (l.group("a"),l.group("b"))
This should work for your given example file.
I am writing code in gfortran to separate a variable time stamp into its separate parts of year, month, and day. I have written this code so the user can input what the time stamp format will be (ie. YEAR/MON/DAY, DAY/MON/YEAR, etc). This creates a total of 6 possible combinations. I have written code that attempts to deal with this, but I believe it to be ugly and poorly done.
My current code uses a slew of 'if' and 'goto' statements. The user provides 'tsfo', the time stamp format. 'ts' is a character array containing the time stamp data (as many as 100,000 time stamps). 'tsdelim' is the delimiter between the year, month, and day. I must loop from 'frd' (the first time stamp) to 'nlines' (the last time stamp).
Here is the relevant code.
* Choose which case to go to.
first = INDEX(tsfo,tsdelim)
second = INDEX(tsfo(first+1:),tsdelim) + first
if (INDEX(tsfo(1:first-1),'YYYY') .ne. 0) THEN
if (INDEX(tsfo(first+1:second-1),'MM') .ne. 0) THEN
goto 1001
else
goto 1002
end if
else if (INDEX(tsfo(1:first-1),'MM') .ne. 0) THEN
if (INDEX(tsfo(first+1:second-1),'DD') .ne. 0) THEN
goto 1003
else
goto 1004
end if
else if (INDEX(tsfo(1:first-1),'DD') .ne. 0) THEN
if (INDEX(tsfo(first+1:second-1),'MM') .ne. 0) THEN
goto 1005
else
goto 1006
end if
end if
first = 0
second = 0
* Obtain the Julian Day number of each data entry.
* Acquire the year, month, and day of the time stamp.
* Find 'first' and 'second' and act accordingly.
* Case 1: YYYY/MM/DD
1001 do i = frd,nlines
first = INDEX(ts(i),tsdelim)
second = INDEX(ts(i)(first+1:),tsdelim) + first
read (ts(i)(1:first-1), '(i4)') Y
read (ts(i)(first+1:second-1), '(i2)') M
read (ts(i)(second+1:second+2), '(i2)') D
* Calculate the Julian Day number using a function.
temp1(i) = JLDYNUM(Y,M,D)
end do
goto 1200
* Case 2: YYYY/DD/MM
1002 do i = frd,nlines
first = INDEX(ts(i),tsdelim)
second = INDEX(ts(i)(first+1:),tsdelim) + first
read (ts(i)(1:first-1), '(i4)') Y
read (ts(i)(second+1:second+2), '(i2)') M
read (ts(i)(first+1:second-1), '(i2)') D
* Calculate the Julian Day number using a function.
temp1(i) = JLDYNUM(Y,M,D)
end do
goto 1200
* Onto the next part of the code
1200 blah blah blah
I believe this code will work, but I do not think it is a very good method. Is there a better way to go about this?
It is important to note that the indices 'first' and 'second' must be calculated for each time stamp as the month and day can both be represented by 1 or 2 integers. The year is always represented by 4.
With only six permutations to handle I would just build a look-up table with the whole tsfo string as the key and the positions of year, month and day (1st, 2nd or 3rd) as the values. Any unsupported formats should produce an error, which I haven't coded below. When subsequently you loop though your ts list and split an item you know which positions to cast to the year, month and day integer variables:
PROGRAM timestamp
IMPLICIT NONE
CHARACTER(len=10) :: ts1(3) = ["2000/3/4 ","2000/25/12","2000/31/07"]
CHARACTER(len=10) :: ts2(3) = ["3/4/2000 ","25/12/2000","31/07/2000"]
CALL parse("YYYY/DD/MM",ts1)
print*
CALL parse("DD/MM/YYYY",ts2)
CONTAINS
SUBROUTINE parse(tsfo,ts)
IMPLICIT NONE
CHARACTER(len=*),INTENT(in) :: tsfo, ts(:)
TYPE sti
CHARACTER(len=10) :: stamp = "1234567890"
INTEGER :: iy = -1, im = -1, id = -1
END TYPE sti
TYPE(sti),PARAMETER :: stamps(6) = [sti("YYYY/MM/DD",1,2,3), sti("YYYY/DD/MM",1,3,2),&
sti("MM/DD/YYYY",2,3,1), sti("DD/MM/YYYY",3,2,1),&
sti("MM/YYYY/DD",2,1,3), sti("DD/YYYY/MM",3,1,2)]
TYPE(sti) :: thisTsfo
INTEGER :: k, k1, k2
INTEGER :: y, m, d
CHARACTER(len=10) :: cc(3)
DO k=1,SIZE(stamps)
IF(TRIM(tsfo) == stamps(k)%stamp) THEN
thisTsfo = stamps(k)
EXIT
ENDIF
ENDDO
print*,thisTsfo
DO k=1,SIZE(ts)
k1 = INDEX(ts(k),"/")
k2 = INDEX(ts(k),"/",BACK=.TRUE.)
cc(1) = ts(k)(:k1-1)
cc(2) = ts(k)(k1+1:k2-1)
cc(3) = ts(k)(k2+1:)
READ(cc(thisTsfo%iy),'(i4)') y
READ(cc(thisTsfo%im),'(i2)') m
READ(cc(thisTsfo%id),'(i2)') d
PRINT*,ts(k),y,m,d
ENDDO
END SUBROUTINE parse
END PROGRAM timestamp
I would encode the different cases in another way, like this:
module foo
implicit none
private
public encode_datecode
contains
integer function encode_datecode(datestr, sep)
character(len=*), intent(in) :: datestr, sep
integer :: first, second
character(len=1) :: c1, c2, c3
first = index(datestr, sep)
second = index(datestr(first+1:), sep) + first
c1 = datestr(1:1)
c2 = datestr(first+1:first+1)
c3 = datestr(second+1:second+1)
foo = num(c1) + 3*num(c2) + 9*num(c3)
end function encode_datecode
integer function num(c)
character(len=1) :: c
if (c == 'Y') then
num = 0
else if (c == 'M') then
num = 1
else if (c == 'D') then
num = 2
else
stop "Illegal character"
end if
end function num
end module foo
and then handle the legal cases (21, 15, 19, 7, 11, 5) in a SELECT statement.
This takes advantage of the fact that there won't be a 'YDDY/MY/YM' format.
If you prefer better binary or decimal readability, you can also multiply by four or by 10 instead of 3.
I'm trying to create a calculator for my own use . I don't know how to make it so that when the user inputs e.g. 6 for the prompt lets the user type in 6 numbers. So if I wrote 7 , it would give me an option to write 7 numbers and then give me the answer, And if i wrote 8 it will let me write 8 numbers...
if choice == "2" then
os.execute( "cls" )
print("How many numbers?")
amountNo = io.read("*n")
if amountNo <= 2 then print("You cant have less than 2 numbers.")
elseif amountNo >= 14 then print("Can't calculate more than 14 numbers.")
elseif amountNo <= 14 and amountNo >= 2 then
amountNmb = amountNo
if amountNmb = 3 then print(" Number 1")
print("Type in the numbers seperating by commas.")
local nmb
print("The answer is..")
The io.read formats are a bit limiting.
If you want a comma-separated list to be typed, I suggested reading a whole line and then iterating through each value:
local line = io.input("*l")
local total = 0
-- capture a sequence of non-comma chars, which then might be followed by a comma
-- then repeat until there aren't any more
for item in line:gmatch("([^,]+),?") do
local value = tonumber(item)
-- will throw an error if item does not represent a number
total = total + value
end
print(total)
This doesn't limit the count of values to any particular value—even an empty list works. (It is flawed in that it allows the line to end with a comma, which is ignored.)
From what I understand, you want the following:
print "How many numbers?"
amountNo = io.read "*n"
if amountNo <= 2 then
print "You can't have less than 2 numbers."
elseif amountNo >= 14 then
print "Can't calculate more than 14 numbers."
else
local sum = 0
for i = 1, amountNo do
print( ('Enter number %s'):format(i) )
local nmb = io.read '*n'
sum = sum + nmb
end
print( ('The sum is: %s'):format(sum) )
end
If the user separates the numbers with commas, they don't need to state how many they want to add, you can just get them all with gmatch. Also with the right pattern you can ensure you only get numbers:
local line = io.input()
local total = 0
-- match any number of digits, skipping any non-digits
for item in line:gmatch("(%d+)") do
total = total + item
end
With input '4 , 6 , 1, 9,10, 34' (no quotes), then print(total) gives 64, the correct answer