if-statement

问题 I have a data frame like this: A B 2012,2013,2014 2011 2012,2013,2014 2012 2012,2013,2014 2013 2012,2013,2014 2014 2012,2013,2014 2015 I wanted to create a dummy variable, which indicates whether the value in column B exists in column A. 1 indicates the existence, and 0 indicates non-existant. Such that, A B dummy 2012,2013,2014 2011 0 2012,2013,2014 2012 1 2012,2013,2014 2013 1 2012,2013,2014 2014 1 2012,2013,2014 2015 0 I have tried to use %in% to achieve this: df$dummy <- ifelse(df$B %in%

问题 I'm a bit of a noob- and I'm having a hard time... I need a bit of of code that searches a db table to find the row that matches the $id variable. There's a field in that table 'description' that I need to grab. If it's null, I need to show one message, if not another. Here's the code I have (I know I need to add the mysqli escape string, just doing this real quick from memory): $query = "SELECT description FROM posts WHERE id = $id"; $result = mysqli_query($dbc, $query); $row = mysqli_fetch

问题 I'm a bit of a noob- and I'm having a hard time... I need a bit of of code that searches a db table to find the row that matches the $id variable. There's a field in that table 'description' that I need to grab. If it's null, I need to show one message, if not another. Here's the code I have (I know I need to add the mysqli escape string, just doing this real quick from memory): $query = "SELECT description FROM posts WHERE id = $id"; $result = mysqli_query($dbc, $query); $row = mysqli_fetch

问题 I'm a bit of a noob- and I'm having a hard time... I need a bit of of code that searches a db table to find the row that matches the $id variable. There's a field in that table 'description' that I need to grab. If it's null, I need to show one message, if not another. Here's the code I have (I know I need to add the mysqli escape string, just doing this real quick from memory): $query = "SELECT description FROM posts WHERE id = $id"; $result = mysqli_query($dbc, $query); $row = mysqli_fetch

问题 I recently started implementing automatic tests for my code, and I noticed that the CI does not catch the warnings of the compiler - the tests are shown as successful even when there are warnings. I have initially added a flag for the compiler to turn the warnings into errors and allow_failure=True , but the problem is that the compiler stops in the first warning->error and does not go through the entire compilation. I then used the trick explained here to write the warnings into a file, and

问题 I recently started implementing automatic tests for my code, and I noticed that the CI does not catch the warnings of the compiler - the tests are shown as successful even when there are warnings. I have initially added a flag for the compiler to turn the warnings into errors and allow_failure=True , but the problem is that the compiler stops in the first warning->error and does not go through the entire compilation. I then used the trick explained here to write the warnings into a file, and

问题 I am wondering if in a situation like the following (an if/else statement under a for loop) the complexity would be O(n) or O(n^2): for character in string: if character==something: do something else: do something else. Thank you! 回答1: It will be O(n) if 'do something' and 'do something else' are O(1) O(n^2) if 'do something' and 'do something else' are O(n) Basically the complexity of the for loop will depend on the complexity of it components and the no. of loops. 回答2: It depends what you

问题 I am wondering if in a situation like the following (an if/else statement under a for loop) the complexity would be O(n) or O(n^2): for character in string: if character==something: do something else: do something else. Thank you! 回答1: It will be O(n) if 'do something' and 'do something else' are O(1) O(n^2) if 'do something' and 'do something else' are O(n) Basically the complexity of the for loop will depend on the complexity of it components and the no. of loops. 回答2: It depends what you

问题 I'd like to to some thing similar to javascripts var foo = true; foo && doSometing(); but this doesnt seem to work in php. I'm trying to add a class to a label if a condition is met and I'd prefer to keep the embedded php down do a minimum for the sake of readability. so far I've got: <?php $redText='redtext ';?> <label class="<?php if ($requestVars->_name=='')echo $redText;?>labellong">_name*</label> <input name="_name" value="<?php echo $requestVars->_name; ?>"/> but even then the ide is

问题 I'd like to to some thing similar to javascripts var foo = true; foo && doSometing(); but this doesnt seem to work in php. I'm trying to add a class to a label if a condition is met and I'd prefer to keep the embedded php down do a minimum for the sake of readability. so far I've got: <?php $redText='redtext ';?> <label class="<?php if ($requestVars->_name=='')echo $redText;?>labellong">_name*</label> <input name="_name" value="<?php echo $requestVars->_name; ?>"/> but even then the ide is