copy

问题 I wonder of the fastest way to write data from pandas DataFrame to table in postges DB. 1) I've tried pandas.to_sql , but for some reason it takes entity to copy data, 2) besides I've tried following: import io f = io.StringIO() pd.DataFrame({'a':[1,2], 'b':[3,4]}).to_csv(f) cursor = conn.cursor() cursor.execute('create table bbbb (a int, b int);COMMIT; ') cursor.copy_from(f, 'bbbb', columns=('a', 'b'), sep=',') cursor.execute("select * from bbbb;") a = cursor.fetchall() print(a) cursor.close

问题 I wonder of the fastest way to write data from pandas DataFrame to table in postges DB. 1) I've tried pandas.to_sql , but for some reason it takes entity to copy data, 2) besides I've tried following: import io f = io.StringIO() pd.DataFrame({'a':[1,2], 'b':[3,4]}).to_csv(f) cursor = conn.cursor() cursor.execute('create table bbbb (a int, b int);COMMIT; ') cursor.copy_from(f, 'bbbb', columns=('a', 'b'), sep=',') cursor.execute("select * from bbbb;") a = cursor.fetchall() print(a) cursor.close

问题 I want to copy table from aDB to another bDB. So I made a method. I think open 2 database and Using insert query will work but I don't know detail way. -(void)copyDatabaseTableSoruceFileName:(NSString *)source CopyFileName:(NSString *)copy { sqlite3 *sourceDatabase=NULL; sqlite3 *copyDatabase=NULL; NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask,YES); NSString* documentDir = [paths objectAtIndex:0]; //source [self copyFileIfNeed:source path

问题 It's a shame for me, but I did not know that: You should use clone to copy arrays, because that's generally the fastest way to do it. as Josh Bloch states in this blog: http://www.artima.com/intv/bloch13.html I always used System.arraycopy(...) . Both approaches are native, so probably without going deeper into the sources of libraries I can not figure out, why it is so. My question is simple: why is it the fastest way? What is the difference with System.arraycopy ? The difference is

问题 I want to copy my mysql database from my computer to another computer. How can I do this? 回答1: How to copy Mysql database from one Computer to another / backup database using mysqldump We can transfer a MySQL database from one PC to another PC using mysqldump command. We have to create dump file of database to transfer database from one PC to another PC. MySQL database is not portable database i.e. we cannot transfer it from one PC to another PC by copying and pasting it. We can use following

问题 I have two vectors: std::vector<int> v1, v2; // Filling v1 ... And now I need to copy v1 to v2 . Is there any reason to prefer v2 = v1; to std::copy (v1.begin(), v1.end(), v2.begin()); (or vice versa)? 回答1: Generally I would strongly prefer v2 = v1 : It is shorter and makes the intend more clear std::copy won't work if v2 doesn't have the same length as v1 (it won't resize it, so it will retain some of the old elements best case ( v2.size() > v1.size() and overwrite some random data used

问题 I want to create a clone of the structure of our multi-terabyte file server. I know that cp --parents can move a file and it's parent structure, but is there any way to copy the directory structure intact? I want to copy to a linux system and our file server is CIFS mounted there. 回答1: You could do something like: find . -type d >dirs.txt to create the list of directories, then xargs mkdir -p <dirs.txt to create the directories on the destination. 回答2: cd /path/to/directories && find . -type

问题 on a website i want to do this: (simplified) myHandlers = new Array(); for(var i = 0; i < 7; i++) { myHandlers.push(new Handler({ handlerName: 'myHandler'+i, // works, e.g. ->myHandler1, 2, 3 etc. handlerFunc: function(bla) { /*...*/ alert(i); } // doesn't work,all return 7 } } I could set the counter as another attribute of my Handler (which would copy the current value) and use it inside my function, but I guess, there is also a way to actually copy this value, no? 回答1: When handlerFunc is

问题 This looks like a simple question, but I didn't find anything similar here. Since there is no file copy function in C, we have to implement file copying ourselves, but I don't like reinventing the wheel even for trivial stuff like that, so I'd like to ask the cloud: What code would you recommend for file copying using fopen()/fread()/fwrite()? What code would you recommend for file copying using open()/read()/write()? This code should be portable (windows/mac/linux/bsd/qnx/younameit), stable,

问题 I have the following scenario: mylib is a library (for which I have the sources, so I'd like to put them into a Maven project mylib:mylib for example). This library has a jar dependency for which I only have the jar, and it is not to be found in the Maven repository (and I do NOT want to install it there either). To make it compile, something like this would work: add the jar file to the mylib project in a "lib" folder, e.g. "lib/thirdpartylib.jar" and in mylib's pom.xml, add a dependency