types

问题 Is it correct to use obj.constructor === Array to test if an object is an array as suggested here? Does it always returns correct answer compatible with Array.isArray ? 回答1: Depends, there are a few scenarios where it can return a different value, but Array.isArray will work. The Array object for one window is not the the same Array object in another window. var obj = someIframe.contentWindow.someArray; console.log(obj.constructor === Array);//false console.log(Array.isArray(obj));//true The

问题 Given a pandas.DataFrame with a column holding mixed datatypes, like e.g. df = pd.DataFrame({'mixed': [pd.Timestamp('2020-10-04'), 999, 'a string']}) I was wondering how to obtain the datatypes of the individual objects in the column (Series)? Suppose I want to modify all entries in the Series that are of a certain type, like multiply all integers by some factor. I could iteratively derive a mask and use it in loc , like m = np.array([isinstance(v, int) for v in df['mixed']]) df.loc[m, 'mixed

问题 Given a pandas.DataFrame with a column holding mixed datatypes, like e.g. df = pd.DataFrame({'mixed': [pd.Timestamp('2020-10-04'), 999, 'a string']}) I was wondering how to obtain the datatypes of the individual objects in the column (Series)? Suppose I want to modify all entries in the Series that are of a certain type, like multiply all integers by some factor. I could iteratively derive a mask and use it in loc , like m = np.array([isinstance(v, int) for v in df['mixed']]) df.loc[m, 'mixed

问题 Given a pandas.DataFrame with a column holding mixed datatypes, like e.g. df = pd.DataFrame({'mixed': [pd.Timestamp('2020-10-04'), 999, 'a string']}) I was wondering how to obtain the datatypes of the individual objects in the column (Series)? Suppose I want to modify all entries in the Series that are of a certain type, like multiply all integers by some factor. I could iteratively derive a mask and use it in loc , like m = np.array([isinstance(v, int) for v in df['mixed']]) df.loc[m, 'mixed

问题 RequireSome type from another, very simialar question. This question is similar but it should not be a duplicate since here we want to also remove null as well as undefined from properties. Maybe the name shouldn't be Require but something like NonNullable or of this kind. The goal of this type is to specify which fields from a type should not be undefined or null, and return their types without undefined and null. type Question = { id: string; answer?: string | null; thirdProp?: number |

问题 I thought that I realized this relationship: In Python everything is an object, and every object has a type. But what about classes? A class is a blueprint of an object, and an object is instance of a class. But I have read in an article that in Python, classes are themselves objects. I thought that an object cannot exist without its blueprint - its class. But, if class is an object, how it can exist? >>> type.__bases__ (<class 'object'>,) >>> int.__bases__ (<class 'object'>,) >>> str.__bases

问题 I want to make a sum function that works with all Numeric types. This works: object session { def mapReduce[A](f: A => A, combine: (A, A) => A, zero: A, inc: A) (a: A,b: A) (implicit num:Numeric[A]): A = { def loop(acc: A, a: A) = if (num.gt(a, b)) acc else combine(f(a), mapReduce(f, combine, zero, inc)(num.plus(a, inc), b)) loop(zero, a) } def sum(f: Int => Int) (a: Int, b: Int) : Int = { mapReduce(f, (x: Int, y: Int) => x + y, 0, 1)(a, b)} sum(x => x)(3, 4) //> res0: Int = 7 def product(f:

问题 I'm attempting to use the ionic plugin cordova-plugin-dialogs , the plugin is working and I am able to call navigator.notification.alert() and create a native alert prompt but whenever my app builds, I get the following console error: error TS2339: Property 'notification' does not exist on type 'Navigator'. I read online that this could be related to types but I have confirmed that the types for this plugin are installed. 回答1: The way I solved was to add this to my typings.json: "dialogs":

问题 My database has numeric value, which is up to 256-bit unsigned integer. However, spark's decimalType has a limit of Decimal(38,18). When I try to do calculations on the column, exceptions are thrown. java.lang.IllegalArgumentException: requirement failed: Decimal precision 39 exceeds max precision 38". Is there any third-party library or workarounds that solve this issue? Or Spark is designed for numbers smaller than Decimal(38,18)? 来源： https://stackoverflow.com/questions/53074721/how-to-use

问题 All I'm looking for is a list of possible values of classinfo since the documentation doesn't provide one and I can't seem to find one anywhere else online, let alone SO. 回答1: print([t for t in __builtins__.__dict__.values() if isinstance(t, type)]) Output (line-breaks inserted for readability): [ <class '_frozen_importlib.BuiltinImporter'>, <class 'bool'>, <class 'memoryview'>, <class 'bytearray'>, <class 'bytes'>, <class 'classmethod'>, <class 'complex'>, <class 'dict'>, <class 'enumerate'>