for-loop

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 I am currently self-teaching myself C++ using Bjarne Stroustrup's book (2nd ed). In one of the examples, he uses a range-for-loop to read the elements in a vector. When I wrote and compiled the code for myself I get this warning. When I run the code, it seems to be working and calculates the mean. Why am I receiving this warning and should I ignore it? Also, why is the range-for using int instead of double in the example, but still returns a double? temp_vector.cpp:17:13: warning: range-based

问题 How can I convert my Excel VBA code, which currently loops by row, to loop through sets of 20 rows? I understand that the Step function might work together with the following line .Range("V1").Value = Application.Index(vInput1, r, 0) . However, I am unsure of how to amend my code to loop through each batch of 20 rows and shift down by 20 rows to loop through the next set of 20 rows. Note: after 'pasting' each set of 20 rows into .range(V1) , Excel calculations are used to generate the output

问题 I'm trying to do web scraping on Google search by using a list of names as inputs and get dataset in a DataFame. I used selenium for web scraping before, I am having a difficult time building syntax using loops to run a list of names as an input to get the results and scrap each page. Here is my Python code below: baseUrl = 'https://www.google.com/search?q=' pluseUrl = input('CEO: ') url = baseUrl + quote_plus(pluseUrl) browser = webdriver.Chrome(r"C:\Users\...\chromedriver.exe") browser.get

问题 I just discovered that this compiles fine with no error (gcc 5.3): std::vector<whatever> vec; for( e: vec ) // do something All the compiler does is issue this warning: warning: range-based for loop without a type-specifier only available with -std=c++1z or -std=gnu++1z Could someone explain: what that code does (is it only a way to assume auto without typing it, or is there more ?) what c++1z is (I know c++11, c++14, never heard of c++1z...) 回答1: The proposal (which hasn't been accepted, so

问题 I am trying to sneak in an if statement within a loop for a jinja template: </table> <class="container"> <table border ="1"> <caption> BBOXX <caption> <thead class="thead-inverse"> <tr> <th>CU Serial</th> <th>System</th> <th>Version</th> <th>Enable Status</th> </tr> {% for d in client_data %} <tr> <td>{{ d["serial_number"]}} </td> <td>{{ d["hardware_type"]}} </td> {% if {{ d["current_enable_flag"]}} == TRUE %} <td> {{ON}} </td> {% else %} <td> {{OFF}} </td> {% endif %} </tr> {% endfor %} <

问题 At the moment I have a quite long code with a for loop calculating the frequency of the various lengths at different maturities of a dataset, I would like to vectorize the code/find a more elegant solution, however so far I've not been able to work out how to do that. The frequency calculation is a relatively simple one: (count of occurances of a specific length at a certain maturity/total number of females or males)*100 Example data: Species Sex Maturity Length 1 HAK M 1 7 2 HAK M 2 24 3 HAK

问题 At the moment I have a quite long code with a for loop calculating the frequency of the various lengths at different maturities of a dataset, I would like to vectorize the code/find a more elegant solution, however so far I've not been able to work out how to do that. The frequency calculation is a relatively simple one: (count of occurances of a specific length at a certain maturity/total number of females or males)*100 Example data: Species Sex Maturity Length 1 HAK M 1 7 2 HAK M 2 24 3 HAK

问题 I have a dataset df as shown below: id timestamp data group_id 99 265 2019-11-28 15:44:34.027 22.5 1 100 266 2019-11-28 15:44:34.027 23.5 2 101 267 2019-11-28 15:44:34.027 27.5 3 102 273 2019-11-28 15:44:38.653 22.5 1 104 275 2019-11-28 15:44:38.653 22.5 2 I have plotted a graph for a chunk of data grouped by a particular group_id and date, eg. group_id ==3, date =2020-01-01 , using code below: df['timestamp'] = pd.to_datetime(df['timestamp']) GROUP_ID = 2 df = df[df['group_id'] == GROUP_ID]