dictionary

问题 The problem is that I want to use enum as key for a dictionary but I want to dynamically generate the entries using a loop. But I will prefer not to use ? operator because I know I'll fill all keys and I don't want to force ! evaluation for each call. enum Students { A, B, C, // many many students } // class Info(); // some properties like grades and teacher const studentInfo: { [key in Students]: Info }; // won't work const must be initialized const studentInfo: { [key in Students]: Info } =

问题 The problem is that I want to use enum as key for a dictionary but I want to dynamically generate the entries using a loop. But I will prefer not to use ? operator because I know I'll fill all keys and I don't want to force ! evaluation for each call. enum Students { A, B, C, // many many students } // class Info(); // some properties like grades and teacher const studentInfo: { [key in Students]: Info }; // won't work const must be initialized const studentInfo: { [key in Students]: Info } =

问题 I have a DataFrame Column with one long string I would like to Parse. I am new to regex and have not worked with it yet. What I have below only returns the first name.. at best. I am wondering if parsing this string is easier for regex or creating a dictionary to iterate through. Here is what I have at the moment. The order is not always the same (C,W,D,G,UTIL) and I will be writing a for loop to iterate through multiple rows just like this one. import pandas as pd import numpy as np import

问题 I ran the below line of code in Python but got an error titled "TypeError: unhashable type: 'set' ". I want to turn that key to a list. How can I solve this error? dictionary = { 'a' : [[1,2,3],[4,5,6],[7,8,9]], 'b' : 2, {100} : 3 } print(dictionary['a'][1][2]) 回答1: keys of a dictionary must be hashable (or better: immutable). set objects are mutable (like lists) you could use a frozenset instead dictionary = { 'a' : [[1,2,3],[4,5,6],[7,8,9]], 'b' : 2, frozenset({100}) : 3 } A frozenset is a

问题 I have a DataFrame Column with one long string I would like to Parse. I am new to regex and have not worked with it yet. What I have below only returns the first name.. at best. I am wondering if parsing this string is easier for regex or creating a dictionary to iterate through. Here is what I have at the moment. The order is not always the same (C,W,D,G,UTIL) and I will be writing a for loop to iterate through multiple rows just like this one. import pandas as pd import numpy as np import

问题 I ran the below line of code in Python but got an error titled "TypeError: unhashable type: 'set' ". I want to turn that key to a list. How can I solve this error? dictionary = { 'a' : [[1,2,3],[4,5,6],[7,8,9]], 'b' : 2, {100} : 3 } print(dictionary['a'][1][2]) 回答1: keys of a dictionary must be hashable (or better: immutable). set objects are mutable (like lists) you could use a frozenset instead dictionary = { 'a' : [[1,2,3],[4,5,6],[7,8,9]], 'b' : 2, frozenset({100}) : 3 } A frozenset is a

问题 I have a data.frame df where the column x is populated with integers (1-9). I would like to update columns y and z based on the value of x as follows: if x is 1,2, or 3 | y = 1 ## if x is 1,4, or 7 | z = 1 if x is 4,5, or 6 | y = 2 ## if x is 2,5, or 8 | z = 2 if x is 7,8, or 9 | y = 3 ## if x is 3,6, or 9 | z = 3 Below is a data.frame with the desired output for y and z df <- structure(list(x = c(1L, 2L, 3L, 3L, 4L, 2L, 1L, 2L, 5L, 2L, 1L, 6L, 3L, 7L, 3L, 2L, 1L, 4L, 3L, 2L), y = c(1L, 1L,

问题 I'm looking to implement an IEqualityComparer class that stores and compares floating point keys that are rounded to the nearest 0.01. In particular, I want to make sure I implement the GetHashCode method correctly. I would like to make this as efficient as possible. Can I use just use the float value itself as it's own hash? I could multiply by 100, cast to int and use an int as a key, but I'm curious if this can be done with float keys. Note: I would wrap the dictionary in a class to ensure

问题 I'm looking to implement an IEqualityComparer class that stores and compares floating point keys that are rounded to the nearest 0.01. In particular, I want to make sure I implement the GetHashCode method correctly. I would like to make this as efficient as possible. Can I use just use the float value itself as it's own hash? I could multiply by 100, cast to int and use an int as a key, but I'm curious if this can be done with float keys. Note: I would wrap the dictionary in a class to ensure

问题 I have one dictionary Like Dictionary<string, List<string>> first=new Dictionary<string, List<string>>(); I want to bind this dictionary to data table such that data table ColumnName should be key of the dictionary and respective columns should contain their dictionary values. What I tried: Dictionary<string, List<string>> some= new Dictionary<string, List<string>>(); System.Data.DataTable dt = new System.Data.DataTable(); foreach (var entry in some) { if (entry.Value.Count > 0) { dt.Columns