tuples

问题 I am trying to create a function that accepts the name of a .csv data file and a list of strings representing column headings in that file and return a dict object with each key being a column heading and the corresponding value being a numpy array of the values in that column of the data file. My code right now: def columndata(filename, columns): d = dict() for col in columns: with open(filename) as filein: reader = csv.reader(filein) for row in reader: if col in row: d.append(row) return d

问题 I am trying to create a function that accepts the name of a .csv data file and a list of strings representing column headings in that file and return a dict object with each key being a column heading and the corresponding value being a numpy array of the values in that column of the data file. My code right now: def columndata(filename, columns): d = dict() for col in columns: with open(filename) as filein: reader = csv.reader(filein) for row in reader: if col in row: d.append(row) return d

问题 In python, one can declare a tuple explicitly with parenthesis as such: >>> x = (0.25, 0.25, 0.25, 0.25) >>> x (0.25, 0.25, 0.25, 0.25) >>> type(x) <type 'tuple'> Alternatively, without parenthesis, python automatically packs its into a immutable tuple: >>> x = 0.25, 0.25, 0.25, 0.25 >>> x (0.25, 0.25, 0.25, 0.25) >>> type(x) <type 'tuple'> Is there a pythonic style to declare a tuple? If so, please also reference the relevant PEP or link. There's no difference in the "end-product" of

问题 I am attempting to employ C++17 fold expressions and the C++14 indices trick to flatten an arbitrary input consisting of tuples and non-tuples. The expected result should at least conform to these requirements: constexpr auto bare = 42; constexpr auto single = std::tuple{bare}; constexpr auto nested_simple = std::tuple{single}; constexpr auto multiple = std::tuple{bare, bare}; constexpr auto nested_multiple = std::tuple{multiple}; constexpr auto multiply_nested = std::tuple{multiple, multiple

问题 I am attempting to employ C++17 fold expressions and the C++14 indices trick to flatten an arbitrary input consisting of tuples and non-tuples. The expected result should at least conform to these requirements: constexpr auto bare = 42; constexpr auto single = std::tuple{bare}; constexpr auto nested_simple = std::tuple{single}; constexpr auto multiple = std::tuple{bare, bare}; constexpr auto nested_multiple = std::tuple{multiple}; constexpr auto multiply_nested = std::tuple{multiple, multiple

问题 I'm using TensorFlow r1.7 and python3.6.5. I am also very new to TensorFlow, so I'd like easy to read explanations if possible. I'm trying to convert my input data into a dataset of tensors with this function tf.data.Dataset.from_tensor_slices() . I pass my tuple with mixed datatypes into this function. However, when running my code I get this error: ValueError: Can't convert Python sequence with mixed types to Tensor . I want to know why I am receiving this error, and how I can convert my

问题 I'm using TensorFlow r1.7 and python3.6.5. I am also very new to TensorFlow, so I'd like easy to read explanations if possible. I'm trying to convert my input data into a dataset of tensors with this function tf.data.Dataset.from_tensor_slices() . I pass my tuple with mixed datatypes into this function. However, when running my code I get this error: ValueError: Can't convert Python sequence with mixed types to Tensor . I want to know why I am receiving this error, and how I can convert my

问题 a tuple in python (in a code block) is defined by the commas; the parentheses are not mandatory (in the cases below). so these three are all equivalent: a, b = 1, 2 a, b = (1, 2) (a, b) = 1, 2 if i define a function def f(a, b): print(a, b) calling it this way will work: f(2, 3) this will not: f((2, 3)) # TypeError: f() missing 1 required positional argument: 'b' how does python treat tuples differently when they are function arguments? here the parentheses are necessary (i understand why

问题 a tuple in python (in a code block) is defined by the commas; the parentheses are not mandatory (in the cases below). so these three are all equivalent: a, b = 1, 2 a, b = (1, 2) (a, b) = 1, 2 if i define a function def f(a, b): print(a, b) calling it this way will work: f(2, 3) this will not: f((2, 3)) # TypeError: f() missing 1 required positional argument: 'b' how does python treat tuples differently when they are function arguments? here the parentheses are necessary (i understand why

问题 The following works fine on Visual C++ 2015 Update 2. Note that A is non-copyable and A::A is explicit . #include <iostream> #include <tuple> struct A { explicit A(int i) { std::cout << i << " "; } // non-copyable A(const A&) = delete; A& operator=(const A&) = delete; }; template <class... Ts> struct B { std::tuple<Ts...> ts; B(int i) : ts((sizeof(Ts), i)...) { } }; int main() { B<A, A, A, A> b(42); } The goal is to pass the same argument to all tuple elements. It correctly outputs: 42 42 42