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问题 In Dart language how to get MAP keys by values? I have a Map like; { "01": "USD", "17": "GBP", "33": "EUR" } And I need to use values to get keys. How do I do that? 回答1: var usdKey = curr.keys.firstWhere( (k) => curr[k] == 'USD', orElse: () => null); 回答2: If you will be doing this more than a few times on the same data, you should create an inverse map so that you can perform simple key lookup instead of repeated linear searches. Here's an example of reversing a map (there may be easier ways

问题 In the following Python script where "aDict" is a dictionary, what does "_: _[0]" do in the lambda function? sorted(aDict.items(), key=lambda _: _[0]) 回答1: Lets pick that apart. 1) Suppose you have a dict, di: di={'one': 1, 'two': 2, 'three': 3} 2) Now suppose you want each of its key, value pairs: >>> di.items() [('three', 3), ('two', 2), ('one', 1)] 3) Now you want to sort them (since dicts are unordered): >>> sorted(di.items()) [('one', 1), ('three', 3), ('two', 2)] Notice that the tuples

问题 In the following Python script where "aDict" is a dictionary, what does "_: _[0]" do in the lambda function? sorted(aDict.items(), key=lambda _: _[0]) 回答1: Lets pick that apart. 1) Suppose you have a dict, di: di={'one': 1, 'two': 2, 'three': 3} 2) Now suppose you want each of its key, value pairs: >>> di.items() [('three', 3), ('two', 2), ('one', 1)] 3) Now you want to sort them (since dicts are unordered): >>> sorted(di.items()) [('one', 1), ('three', 3), ('two', 2)] Notice that the tuples

问题 Ok so I am given two columns A S A T A Z B F B G B P B U C D C P C R D M E H F S H U The 1st column is a list of points, and the second column is the list of the neighbors of the points. I would like to make it a dictionary so that {A:'S','T','Z', B:'F','G','P' etc} and so on. What I have tried doing is this, given that the text file is the two columns. edges = open('romEdges.txt') edgeslist = edges.read().split() edgeskeys = edgeslist[::2] edgesvalues = edgeslist[1::2] dictionary = {} for

问题 Ok so I am given two columns A S A T A Z B F B G B P B U C D C P C R D M E H F S H U The 1st column is a list of points, and the second column is the list of the neighbors of the points. I would like to make it a dictionary so that {A:'S','T','Z', B:'F','G','P' etc} and so on. What I have tried doing is this, given that the text file is the two columns. edges = open('romEdges.txt') edgeslist = edges.read().split() edgeskeys = edgeslist[::2] edgesvalues = edgeslist[1::2] dictionary = {} for

问题 I have looked for a solution to detect if multiple keys are pressed in C# (I couldn't find a solution!). I have this game with two players and I need to detect if a key is pressed to move them around. (I'm Using C# Forms) I've only found answers to detect if two keys are held down at the same time and they didn't help. --EDIT-- How to detect if a key is pressed using KeyPressed (C#) 回答1: The source of the problems is that this simple request is simply not supported under Winforms. Sounds

问题 I have looked for a solution to detect if multiple keys are pressed in C# (I couldn't find a solution!). I have this game with two players and I need to detect if a key is pressed to move them around. (I'm Using C# Forms) I've only found answers to detect if two keys are held down at the same time and they didn't help. --EDIT-- How to detect if a key is pressed using KeyPressed (C#) 回答1: The source of the problems is that this simple request is simply not supported under Winforms. Sounds

问题 Forgive me if this is obvious, but I'm very, very new to Python. I've found ways to get multiple keys from a dictionary, but that's not what I'm trying to do. Basically I'm looking for something like this: my_dict = { "1-10" : "foo", "11-20" : "bar", # ... "91-100" : "baz" } ... but where the keys aren't actually strings and any number in that given range maps to the value. So for example, my_dict[9] ought to return foo , just as my_dict[3] should. I thought of using an explicit array, like

问题 dpressed = 0 def on_press(key): if key == ('d'): global dpressed dpressed+=1 logging.info("D: %s" % dpressed) When I run this code and press d, nothing happens, which I suspect is because the key needs to be called something else when checked. Does someone know what it should be? 回答1: For anyone else that may have this problem, I imported KeyCode from pynput.keybord at the top. Then I changed ('d') to KeyCode.from_char('d'). This should work for anyone with this problem. There is a great

问题 I'm currently working on a script that presses the ' w,a,s,d ' keys in order to move a character in any game. For this to work, i need to have the ' w ' key pressed for a specific amount of time. How can I achieve this? I thought of something like: pyautogui.keyDown('w') time.sleep(2) pyautogui.keyUp('w') But this just pauses the whole program and no key is being pressed so this has no use to me. 回答1: As said in the doc-string from pyautogui.keyDown() : Performs a keyboard key press without