formula

问题 I'm in a situation where I have a vector full of column names for a really large data frame. Let's assume: x = c("Name", "address", "Gender", ......, "class" ) [approximatively 100 variables] Now, I would like to create a formula which I'll eventually use to create a HoeffdingTree . I'm creating formula using: myformula <- as.formula(paste("class ~ ", paste(x, collapse= "+"))) This throws up the following error: Error in parse(text = x) : :1:360: unexpected 'else' 1:e+spread+prayforsonni+just

问题 I have a list that looks like: A B C D E F G How do I solve this to find all combinations for 3 digits. The same letter cannot be used in same row. ABC ABD ABE ABF ABG AGB E.g something like...: x = ['a','b','c','d','e'] n = 3 import itertools aa = [list(comb) for i in range(1, n+2) for comb in itertools.combinations(x, i)] print(aa) This does not give desired input: [['a'], ['b'], ['c'], ['d'], ['e'], ['a', 'b'], ['a', 'c'], ['a', 'd'], ['a', 'e'], ['b', 'c'], ['b', 'd'], ['b', 'e'], ['c'

问题 I'm writing my first S3 class and associated methods and I would like to know how to subset my input data set in order to keep only the variables specified in the formula? data(iris) f <- Species~Petal.Length + Petal.Width With model.frame(f,iris) I get a subset with all the variables in the formula. How to automatically keep only the right hand side variables (in the example Petal.Length and Petal.Width )? 回答1: You want labels and terms ; see ?labels , ?terms , and ?terms.object . labels

问题 I am currently learning python through a video tutorial on youtube, and have come up against a formula I cannot seem to grasp, as nothing looks right to me. The basic concept of the excersise is to make a mortgage calculator that asks the user to input 3 pieces of information, Loan Amount, Interest Rate, and Loan Term (years) then it calculates the monthly payments to the user. here is my code: __author__ = 'Rick' # This program calculates monthly repayments on an interest rate loan/mortgage.

问题 How to show an easy latex-formula in python? Maybe numpy is the right choice? EDIT: I have python code like: a = '\frac{a}{b}' and want to print this in a graphical output (like matplotlib). 回答1: As suggested by Andrew little work around using matplotlib. import matplotlib.pyplot as plt a = '\\frac{a}{b}' #notice escaped slash plt.plot() plt.text(0.5, 0.5,'$%s$'%a) plt.show() 回答2: Matplotlib can already do TeX, by setting text.usetex: True in ~/.matplotlib/matplotlibrc . Then, you can just

问题 How can I make my text look like the image below using CSS? 回答1: First of all you need to use a mono-space font. You can find some pretty nice looking ones over at Google Fonts. The font in the image is Ubuntu Mono. Secondly, we are going to be using Viewport Width, or 'vw' unit (If you clicked the link, you'd see that it is well supported by browsers). You need to make sure the top line of text is the width you need it be to fit the width. This also means that each line needs to be it's own

问题 I need to enable user that he can write own formula in datagridview. Something like a function in Excel. Example of formula definition: So, user write his own formula in formula cell and then in other table is shown result for each. How I can do this? 回答1: I would try NCalc NCalc is a mathematical expressions evaluator in .NET. NCalc can parse any expression and evaluate the result, including static or dynamic parameters and custom functions. Dictionary<string, int> dict = new Dictionary

问题 How do I create a formula that isn't made invalid when I delete a row. For example in cell F12 I have the formula: =F11+D12-E12 This basically says take the value from the cell above then add the value of the cell 2 to the left and subtract the value in the cell directly to the left. However, because I'm using actual cell addresses, as soon as I delete a row, all the rows below become invalid. How do i express the formula by relative position (ie = "1 above" + "2 to left" - "1 to left")

问题 I'm looking for a math formula that on a graph plotting Y as a function of X, before a specified starting point (a value of X, or even better, X and Y coordinates) will have a certain slope, then after that it will draw an arc of a specified radius that will end when it reaches a second specified slope, and from the point on will be another straight line of that second slope. I'm am aware that because it's Y as a function of X, the slope parameters would need to be bigger than exactly -90 and

问题 I have the following formula that I use regularly to copy information from one file to another. Essentially, it takes a given id (A2) and searches for it's match in the second spreadsheet, then copies the data from the column specified in the first part of the formula (in this case, C). =INDEX([spreadsheet.xlsx]Sheet1!$C$2:$C$50000,MATCH(A2,[spreadsheet.xlsx]Sheet1!$B$2:$B$50000,0)) The formula works perfectly on all columns except when I try to transfer dates. It ALWAYS transfers a date