将字符串转换为数值方程 [英] Turning String into Numerical Equation
问题描述
这是我的问题，希望有人可以帮我弄清楚是否有好的方法可以做到这一点。
我写的允许用户使用预先存在的变量在文本
字段中输入等式的程序。然后他们输入这些变量的数值，或者告诉程序将
中使用的值随机化为某个边界。我的问题是他们在文本字段中写了这个等式，并将它转换成Python可以计算的等式。
我知道的唯一方法要做到这一点是通过解析它，这可以得到相当不错的b $ b令人讨厌的所有不同的数学规则。有没有人比解析从字符串计算方程式更好的想法
表示？
非常感谢！
Brian Kazian
Brian Kazian写道：这里是'我的问题，希望有人可以帮我弄清楚是否有这样做的好方法。
我正在编写一个程序，允许用户在文本中输入方程
字段使用预先存在的变量。然后，他们输入这些变量的数值，或者告诉程序将
中使用的值随机化为某个边界。我的问题在于他们在文本字段中编写的这个等式并将其转换为Python可以计算的等式。
我知道这样做的唯一方法是解析它，所有不同的数学规则都会变得非常糟糕。有没有人比解析从字符串
表示计算方程更好？
非常感谢！
Brian Kazian
eval（）
请参阅： http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH，
-ag
-
Artie Gold - 奥斯汀，德克萨斯州
http://it-matters.blogspot.com （新的发布12/5）
http://www.cafepress.com/goldsays
感谢您的帮助，我甚至没想到。
我在猜那里处理指数或对数
函数并不容易？我也会遇到这两种类型。
" Artie Gold" < AR ******* @ austin.rr.com>在消息中写道
news：39 ************* @ individual.net ...Brian Kazian写道：这是我的问题，希望有人可以帮我弄清楚
是否是一个很好的方法。
我正在编写一个程序，允许用户使用预先存在的变量在
文本字段中输入等式。然后，他们为这些变量输入数值，或者可以告诉程序随机化在某个范围内使用的值。我的问题在于他们在文本字段中编写的这个等式，并将其转换为Python可以计算的等式。
我知道这样做的唯一方法是通过解析它，可能会因为所有不同的数学规则而变得非常讨厌。有没有人比解析从字符串
表示计算方程有更好的想法？
非常感谢！
Brian Kazian
eval（）
请参阅： http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH，
- -G
- Artie Gold - 德克萨斯州奥斯汀
http://it-matters.blogspot.com （新帖子12/5）
http://www.cafepress.com/goldsays
Brian Kazian写道：感谢您的帮助，我甚至没想到。
我猜测处理指数或对数函数没有简单的方法？我也将遇到这两种类型。
嗯，请考虑：
导入数学
eval（" log（pow（x，2） * pow（y，3），2）"，{''pow''：math.pow，''og''：math.log}，{''x''：1，''y'' ：2}）
[不，你不想这样写;它只是说明了你能做什么而不用多少钱。
HTH，
--ag
[BTW - 文化问题：我们在这里发帖吗？]
" Artie Gold" < AR ******* @ austin.rr.com>在消息中写道
新闻：39 ************* @ individual.net ...
Brian Kazian写道：
这是我的问题，希望有人可以帮我弄清楚
是否是一个很好的方法。
我正在写一个程序允许用户使用预先存在的变量在
文本字段中输入等式。然后，他们为这些变量输入数值，或者可以告诉程序随机化在某个范围内使用的值。我的问题在于他们在文本字段中编写的这个等式，并将其转换为Python可以计算的等式。
我知道这样做的唯一方法是通过解析它，可能会因为所有不同的数学规则而变得非常讨厌。有没有人比解析从字符串
表示计算方程有更好的想法？
非常感谢！
Brian Kazian
eval（）
请参阅： http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH，
- ag
- Artie Gold - 德克萨斯州奥斯汀
http://it-matters.blogspot.com （新帖子12/5）
http://www.cafepress.com/goldsays
-
Artie Gold - 德克萨斯州奥斯汀
http：/ /it-matters.blogspot.com （新帖子12/5）
http://www.cafepress.com/go ldsays
Here''s my problem, and hopefully someone can help me figure out if there is
a good way to do this.
I am writing a program that allows the user to enter an equation in a text
field using pre-existing variables. They then enter numerical values for
these variables, or can tell the program to randomize the values used within
a certain bounds. My problem is taking in this equation they have written
in the text field and converting it into an equation Python can calculate.
The only way I know of to do this is by parsing it, which could get pretty
nasty with all of the different mathematical rules. Does anyone have a
better idea than parsing to compute an equation from a string
representation?
Thanks so much!
Brian Kazian
Brian Kazian wrote:Here''s my problem, and hopefully someone can help me figure out if there is
a good way to do this.
I am writing a program that allows the user to enter an equation in a text
field using pre-existing variables. They then enter numerical values for
these variables, or can tell the program to randomize the values used within
a certain bounds. My problem is taking in this equation they have written
in the text field and converting it into an equation Python can calculate.
The only way I know of to do this is by parsing it, which could get pretty
nasty with all of the different mathematical rules. Does anyone have a
better idea than parsing to compute an equation from a string
representation?
Thanks so much!
Brian Kazian
eval()
See: http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH,
--ag
--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays
Thanks for the help, I didn''t even think of that.
I''m guessing there''s no easy way to handle exponents or logarithmic
functions? I will be running into these two types as well.
"Artie Gold" <ar*******@austin.rr.com> wrote in message
news:39*************@individual.net...Brian Kazian wrote:Here''s my problem, and hopefully someone can help me figure out if there
is a good way to do this.
I am writing a program that allows the user to enter an equation in a
text field using pre-existing variables. They then enter numerical
values for these variables, or can tell the program to randomize the
values used within a certain bounds. My problem is taking in this
equation they have written in the text field and converting it into an
equation Python can calculate.
The only way I know of to do this is by parsing it, which could get
pretty nasty with all of the different mathematical rules. Does anyone
have a better idea than parsing to compute an equation from a string
representation?
Thanks so much!
Brian Kazian
eval()
See: http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH,
--ag
--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays
Brian Kazian wrote:Thanks for the help, I didn''t even think of that.
I''m guessing there''s no easy way to handle exponents or logarithmic
functions? I will be running into these two types as well.
Well, consider:
import math
eval("log(pow(x,2)*pow(y,3),2)",{''pow'':math.pow,''l og'':math.log},{''x'':1,''y'':2})
[No, you wouldn''t want to write it that way; it''s merely illustrating
what you can do without doing much.]
HTH,
--ag
[BTW -- cultural question: Do we top-post here?]
"Artie Gold" <ar*******@austin.rr.com> wrote in message
news:39*************@individual.net...Brian Kazian wrote:Here''s my problem, and hopefully someone can help me figure out if there
is a good way to do this.
I am writing a program that allows the user to enter an equation in a
text field using pre-existing variables. They then enter numerical
values for these variables, or can tell the program to randomize the
values used within a certain bounds. My problem is taking in this
equation they have written in the text field and converting it into an
equation Python can calculate.
The only way I know of to do this is by parsing it, which could get
pretty nasty with all of the different mathematical rules. Does anyone
have a better idea than parsing to compute an equation from a string
representation?
Thanks so much!
Brian Kazian
eval()
See: http://docs.python.org/lib/built-in-funcs.html#l2h-23
HTH,
--ag
--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays
--
Artie Gold -- Austin, Texas
http://it-matters.blogspot.com (new post 12/5)
http://www.cafepress.com/goldsays
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