simplification

问题 I have a lot of expressions which sympy default writes as sums of products of variables. These expressions can get quite long. I would like to simplify these expressions to have as few as possible multiplications. A reduced example: from sympy import symbols, cse, factor, simplify, count_ops, collect a,b,c=symbols("a b c", integer=True, positive=True) e = a*a*b + a*a + a*b*b + a*b*c + 4*a*b + a*c + 3*a + b*b*c + 4*b*c + 3*c + 1 What I would like to get is something like: (a + b + 3) * (a + c)

问题 I've been trying to carry out line simplification on polygons belonging to maps with the help of this CGAL guide, e.g. South Korea. This is a screenshot of South Korea after line simplification with CGAL. I carried out the line simplification by adding each polygon to CGAL::Constrained_triangulation_plus_2<CDT> ct and then running CGAL::Polyline_simplification_2::simplify(ct, Cost(), Stop(0.5)); . The outer boundaries will get simplified but the inner/shared boundaries (between provinces)

问题 I have some particular dimensionless numbers commonly used in fluid mechanics. I want to express a certain expression in terms of these variables. If I define my dimensionless numbers and then do simplify(*expression*) where the expression is a function of variables that have all been used at least once in the definition of the dimensionless numbers, is it able to give this expression in terms of these dimensionless numbers? Can it be used to save time with this sort of algebra? Many thanks !

问题 I am trying to turn a Map("a" -> 2, "b" -> 1) into seq("a","a","b") through the map function, Currently I am trying to run the code below giving me the desired result. Is there a smarter way to do this? Possibly a better way through the map function? var multiset : Seq[T] = Seq[T]() var variables : Seq[T] = data.map(x => x._1).toSeq var variableCounts : Seq[Int] = data.map(x => x._2).toSeq for(x <- 0 until variables.length){ for(y <- 0 until variableCounts(x)) multiset = multiset :+ variables

问题 I am trying to turn a Map("a" -> 2, "b" -> 1) into seq("a","a","b") through the map function, Currently I am trying to run the code below giving me the desired result. Is there a smarter way to do this? Possibly a better way through the map function? var multiset : Seq[T] = Seq[T]() var variables : Seq[T] = data.map(x => x._1).toSeq var variableCounts : Seq[Int] = data.map(x => x._2).toSeq for(x <- 0 until variables.length){ for(y <- 0 until variableCounts(x)) multiset = multiset :+ variables

问题 I am trying to turn a Map("a" -> 2, "b" -> 1) into seq("a","a","b") through the map function, Currently I am trying to run the code below giving me the desired result. Is there a smarter way to do this? Possibly a better way through the map function? var multiset : Seq[T] = Seq[T]() var variables : Seq[T] = data.map(x => x._1).toSeq var variableCounts : Seq[Int] = data.map(x => x._2).toSeq for(x <- 0 until variables.length){ for(y <- 0 until variableCounts(x)) multiset = multiset :+ variables

问题 i want to disable automatic simplification in sympy, for example solving the equation x*y-x i want to get x/x instead of 1 import sympy from sympy.abc import x,y,z expr = x*y-x sympy.solve(expr,y) => 1 # i want unsimplified x/x instead of 1 From the sympy manual, i found UnevaluatedExpr for this purpose, but it returns empty list for the example given from sympy import UnevaluatedExpr expr1 = UnevaluatedExpr(x)*UnevaluatedExpr(y)-UnevaluatedExpr(x) sympy.solve(expr1,y) => [] my question is

问题 i want to disable automatic simplification in sympy, for example solving the equation x*y-x i want to get x/x instead of 1 import sympy from sympy.abc import x,y,z expr = x*y-x sympy.solve(expr,y) => 1 # i want unsimplified x/x instead of 1 From the sympy manual, i found UnevaluatedExpr for this purpose, but it returns empty list for the example given from sympy import UnevaluatedExpr expr1 = UnevaluatedExpr(x)*UnevaluatedExpr(y)-UnevaluatedExpr(x) sympy.solve(expr1,y) => [] my question is

问题 I have a simple example I've drawn up. I thought it was possible to combine if statements and for loops with minimal effort in Python. Given: sublists = [number1, number2, number3] for sublist in sublists: if sublist: print(sublist) I thought I could condense the for loop to: for sublist in sublists if sublist: but this results in invalid syntax. I'm not too particular on this example, I just want a method of one lining simple if statements with loops. 回答1: if you want to filter out all the

问题 I have a simple example I've drawn up. I thought it was possible to combine if statements and for loops with minimal effort in Python. Given: sublists = [number1, number2, number3] for sublist in sublists: if sublist: print(sublist) I thought I could condense the for loop to: for sublist in sublists if sublist: but this results in invalid syntax. I'm not too particular on this example, I just want a method of one lining simple if statements with loops. 回答1: if you want to filter out all the