shift

问题 > tempDT <- data.table(colA = c("E","E","A","A","E","A","E") + , lags = c(NA,1,1,2,3,1,2)) > tempDT colA lags 1: E NA 2: E 1 3: A 1 4: A 2 5: E 3 6: A 1 7: E 2 I have column colA , and need to find lags between current row and the previous row whose colA == "E" . Note: if we could find the row reference for the previous row whose colA == "E" , then we could calculate the lags. However, I don't know how to achieve it. 回答1: 1) Define lastEpos which given i returns the position of the last E

问题 I have a script to launch some checks on Ubuntu machine. I call my script like this : ./script -f /tmp/file.txt --modules 001 002 003 All files 001, 002, etc... are bash scripts. The following main function is my problem : main () { OPTS=`getopt -o hf:m: --long help,file:,modules: -n 'script.sh' -- "$@"` eval set -- "$OPTS" [ $# -eq 0 ] && echo "Unknown options or parameters" && USAGE while [ $# -gt 0 ]; do case "$1" in -f|--file) FILE="$2" shift ;; -h|--help) USAGE exit 1 ;; -m|--modules)

问题 Suppose I have a DataFrame (or Series) like this: Value 0 0.5 1 0.8 2 -0.2 3 None 4 None 5 None I wish to create a new Result column. The value of each result is determined by the previous Value, via an arbitrary function f . If the previous Value is not available (None or NaN), I wish to use instead the previous Result (and apply f to it, of course). Using the previous Value is easy, I just need to use shift . However, accessing the previous result doesn't seem to be that simple. For example

问题 I want to check overlap of data, here is data ID <- c(rep(1,3), rep(3, 5), rep(4,4),rep(5,5)) Begin <- c(0,2.5,3,7,8,7,25,25,10,15,17,20,1,NA,10,11,13) End <- c(1.5,3.5,6,12,8,11,29,35, 12,19,NA,28,5,20,30,20,25) df <- data.frame(ID, Begin, End) df ID Begin End 1 1 0.0 1.5 2 1 2.5 3.5 3 1 3.0 6.0* 4 3 7.0 12.0 5 3 8.0 8.0* 6 3 7.0 11.0* 7 3 25.0 29.0 8 3 25.0 35.0* 9 4 10.0 12.0 10 4 15.0 19.0 11 4 17.0 NA* 12 4 20.0 28.0 13 5 1.0 5.0 14 5 NA 20.0 15 5 10.0 30.0 16 5 11.0 20.0* 17 5 13.0 25.0

问题 I am writing some code to type strings using the Robot class. Everything is mostly good (well, I have to use a big switch statement to get character keycodes), except some keys don't have keycodes, because they are actually a combination of Shift + some other key. For upper case letters, it is easy to check, using Character.isUpperCase(c) , but for all the symbols such as !@#$%^&*()_+ and various punctuation are not considered "upper case" although they do require shift to be pressed in order

问题 This question already has answers here : Weird behavior of right shift operator (1 >> 32) (7 answers) Closed 4 years ago . Can someone explain me why right 32 bitwise shift of some 4 byte integer number may return not zero in C/C++ ? Why does it depend on -O option of the compiler? For example this code gives 45 with -O0 and 0 with -O3 options in gcc 4.8.3: unsigned int x = 45; // 4 bytes x = x >> 32; printf("%u\n", x); Why it is like this? 回答1: Because it is undefined behavior: [expr.shift]

问题 I'm trying to convert some data from hex to base64 in C, I found an algorithm online but I would really like to know how it works rather than just implenting it and firing it off. If someone could please explain how the following is working I would appreciate it. I have been reading about the shift operators and I don't seem to understand them as much as I thought I did...it's not quite clicking for me. for (x = 0; x < dataLength; x += 3) { /* these three 8-bit (ASCII) characters become one

问题 I have a variable (unsigned int) part_1 . If I do this: NSLog(@"%u %08x", part_1, part_1); (print unsigned value, and hex value) it outputs: 2063597568 7b000000 (only first two will have values). I want to convert this to 0000007b So i've tried doing unsigned int part_1b = part_1 >> 6 (and lots of variations) But this outputs: 32243712 01ec0000 Where am i going wrong? 回答1: You want to shift by 6*4 = 24 bits, not just 6 bits. Each '0' in the hex printf represents 4 bits. unsigned int part_1b =

问题 I recently discovered that different browsers handle the onclick event differently when the Control or Shift keys are pressed. They diverge similarly on behavior for for following links by clicking the middle mouse button. With the following link: <a href="http://www.example.com/" onclick="alert('onclick');">go to example.com</a> Onclick browser support table Mouse Keyboard Chrome Firefox Safari Opera IE5.5 IE6 IE7 IE8 IE9 Left None yes yes yes yes yes yes yes yes yes Left Ctrl yes yes yes

问题 I'm trying to figure out if there is any way in which we can detect if shift key is pressed or if any notification is sent when shift key is pressed in UIKeyboard - (BOOL) textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)string does not get called for shift key press since it is a modifier key. 回答1: Don't know whether you need to know it in combination with other text or only detect the single shift tap, but here is my solution for detecting