Well. I was copying files from my hard disk to a flash drive. In the middle of it, I click the cancel button. After that, I was not able to copy any file to it or delete file from it. I can't even format it.
The message I got is 'write protected'.
I googled for solutions, there are basically two kind of posting:
1. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\StorageDevicePolicies
2. diskpart
I tried both, but neither one worked.
I did followed the diskpart instruction and was able to play it with a new USB flash drive. The diskpart is basically a text based utility. Once you type the diskpart in the Run or DOS Command window, a terminal like window is popped up and you can issue text commands. Type help and hit enter will show you all the command available. Typing help and a command name will show you how a given command is for and how it is used.
In my USB case, it seems that my USB is dead - I can issue the clear read-only status command and be notified the successful of the command. But when I check status, the read-only status is still set. With my new USB, the diskpart worked like a charm.
Note: There are status for both the 'disk' and 'volume'. You need to check/reset both.
Now - did cancel a copy command killed my USB drive? I don't know. But at this point, I have broken quite few USB drive with no obvious reason - it seems to me it is really un-reliable - worst than the 3.5 inch floppy disk.
I really wondering if there are any statistics about the reliability of the USB drive.
Added on Feb. 5, 2011=============
I actually read some articles about how the USB drive works and a report on the usability of the USB drive. It seems to me that USB drive suppose to be quite reliable - especially for reading only operation. At this moment, I attributed my problem to my frequent writing to the USB drive. I constantly bring work home with the USB drive and, therefore, writing to the USB drive quite often. Based on some articles, the writing to USB is in blocks. So, a single change in a file could result in a lot of writings. My proposal is to keep adding to the USB until it is full. I will then deleted the oldest content and reuse that part of the memory. My hope is that by adding to the USB, I am writing across the USB and distribute my writing over the whole USB instead of writing to the same area over and over again. Hopefully this will extend the life of the USB.
Friday, January 14, 2011
Thursday, September 9, 2010
Idea for navigating tags
Related Articles:
Tag, path and weighted tag
As mentioned in previous article, there are pros and cons for either the path or tag approaches in classifying information.
A problem with tags is that a single tag may associated with a lot of information that may or may not related to the specific interest of a particular search incidence. For example, a 'statistics' tag may associated with education, mathematics, physics, program ... etc. A single search of statistics becomes useless.
A possible approach is to make the search a tree/branch-liked search: Once a tag-of-interest is identified, the search program will create a list of data items that are tagged with the searching tag. The program will, then, collect all tags from these data items and try to present choices for the next tag selection and so on. By implement it right, tags can be considered a dynamic tree/path structure.
Tag, path and weighted tag
As mentioned in previous article, there are pros and cons for either the path or tag approaches in classifying information.
A problem with tags is that a single tag may associated with a lot of information that may or may not related to the specific interest of a particular search incidence. For example, a 'statistics' tag may associated with education, mathematics, physics, program ... etc. A single search of statistics becomes useless.
A possible approach is to make the search a tree/branch-liked search: Once a tag-of-interest is identified, the search program will create a list of data items that are tagged with the searching tag. The program will, then, collect all tags from these data items and try to present choices for the next tag selection and so on. By implement it right, tags can be considered a dynamic tree/path structure.
Monday, June 21, 2010
Android mothership tablet for Android phone
Here's an idea: Make Android tablet a mothership for Android phone. The connection between them is Wifi.
The tablet do not need camera, phone and GIS capabilities. But it can take advantage of those from the Android phone. You don't want to hold the hold tablet to take a picture anyway.
So how do you think?
The tablet do not need camera, phone and GIS capabilities. But it can take advantage of those from the Android phone. You don't want to hold the hold tablet to take a picture anyway.
So how do you think?
Wednesday, June 2, 2010
The Chrome OS and future
Imaging a world with Chrome, almost all people will using programs on the cloud. Personal devices need very little computing power.
For well connected humans lived on Earth, this will not be a problem. For space traveler, powerful computer will be needed if the connection can't be established easily to the Earth.
How safe private data can be kept could be a problem. One can easily encrypts data and saved in the cloud. However, if you want process those data, you will need to get your data from the cloud, un-encrypted and process it. But if programs were also running in the cloud, you will need to send the data to the program to process. Then, how can you know no one in the processing cloud will not peek at your data? One of the reason the encryption works if because the user can run the encryption program at his own isolated machine, assuming his isolated machine is powerful enough to handle that.
Is it possible to package a cloud program that is isolated from inspection/peek?
The personal devices will become very cheep since it does not need a lot of computing power. At the same time, it will become pricey to get a decent computing machine since the demand is low. To be able to own such machine, people will need make money by providing cloud services. Otherwise, you will become a machine-less individual.
For well connected humans lived on Earth, this will not be a problem. For space traveler, powerful computer will be needed if the connection can't be established easily to the Earth.
How safe private data can be kept could be a problem. One can easily encrypts data and saved in the cloud. However, if you want process those data, you will need to get your data from the cloud, un-encrypted and process it. But if programs were also running in the cloud, you will need to send the data to the program to process. Then, how can you know no one in the processing cloud will not peek at your data? One of the reason the encryption works if because the user can run the encryption program at his own isolated machine, assuming his isolated machine is powerful enough to handle that.
Is it possible to package a cloud program that is isolated from inspection/peek?
The personal devices will become very cheep since it does not need a lot of computing power. At the same time, it will become pricey to get a decent computing machine since the demand is low. To be able to own such machine, people will need make money by providing cloud services. Otherwise, you will become a machine-less individual.
Tuesday, March 30, 2010
An introduction to R statistics
Recently, I spent some time learning the R environment. It take me a little while to Get-It. So I would like to describe the system in my way and hope it will help those brain that are wired like mine. There is no intention in covering the detail of R, but the basics.
The R environment data are objects that can have properties. But these objects do not have method. So, we can say they are more like a C structure than full featured objects. Also, R does not support the Object.Property or Object.method() syntax. Instead, the dot (.) is an allowable character for identifiers. Properties and methods are accessed through functions. So, the bottom line is R objects are like C structures. With this approach in mind, we can better understand the limitation of R and how it is constructed.
With this approach to objects, functions can be made to operate on multiple type of objects by knowing the type of the object. In R, properties for basic types are documented. The intrinsic properties are: mode, length and class. These properties can only be accessed through special functions: mode(), length() and class(). Other properties/attributes are accessed through attr(). The list of attributes can be viewed with attributes().
R supports the syntax of vector operation. For example, A*B can mean the multiplication of two vectors. This approach makes R an idea tool for expressing matrix operations and carrying out operations related to tabulated data, like those in the linear algebra and statistic survey.
Basic Data Type: Vector
The simplest R object type is the vector, which is an ordered list of components of the same kind. Component can be numeric, complex, character, logical, NA and others. Vectors have the mode property, where mode can be numeric, complex, character, logical and others. You use the mode() function to obtain access to the mode property. The other property of vectors is the length, or the number of components, and it can be accessed through the length() function. The names property is also supported. names property is a vector itself and gives each component a name. Components can be referred to by either integer indexes or their names.
Basic Data Type: Factor
Factor is an vector object with the levels property. Property levels is a vector of unique values of the original vector. This give those values an order.
R objects also have a property called class. The class of a vector is simply its mode. The class of a Factor is 'factor'. The class property can be accessed via class() function.
Basic Data Type: Array
Array is an vector object with dim property. The dim is a positive integer vector. The component of the dim vector specifies the size of each dimension. Matrix is an array of two dimensions. The mode of an array is the same as the mode of its component. The class of an array is 'array'. Array can be created by combining vectors or by setting a vector's dim property.
Basic Data Type: List
By combing objects of different type in an ordered list, we created a list object. List object can have a names property that is a vector of mode character and it gives each list-component a name. List objects have the class property set to 'list'.
Basic Data Type: data.frame
data.frame object is considered as an extension of list object with restrictions placed on the size of the list-component so that the data.frame resemble a table like structure with each column has the same number of values. These list-components can be vectors, factors, matrix or lists. data.frame have the class of 'data.frame'.
Useful Function/Operators
Environmental
getwd(), setwd(), objects(), ls(), library()
Constructors
Bgn:End (colon), c(), vector(), factor(), list(), data.frame(), matrix(), cbind(), rbind(), matrix()
Casting
as.vector(), as.factor() ...
Indexing
Other
assign(), <-, ->, grep(), function(), tapply(), is.na(), is.vector(), summary(), names()
& (element-wise), | (element-wise), &&, ||
Control Structure
The R environment data are objects that can have properties. But these objects do not have method. So, we can say they are more like a C structure than full featured objects. Also, R does not support the Object.Property or Object.method() syntax. Instead, the dot (.) is an allowable character for identifiers. Properties and methods are accessed through functions. So, the bottom line is R objects are like C structures. With this approach in mind, we can better understand the limitation of R and how it is constructed.
With this approach to objects, functions can be made to operate on multiple type of objects by knowing the type of the object. In R, properties for basic types are documented. The intrinsic properties are: mode, length and class. These properties can only be accessed through special functions: mode(), length() and class(). Other properties/attributes are accessed through attr(). The list of attributes can be viewed with attributes().
R supports the syntax of vector operation. For example, A*B can mean the multiplication of two vectors. This approach makes R an idea tool for expressing matrix operations and carrying out operations related to tabulated data, like those in the linear algebra and statistic survey.
Basic Data Type: Vector
The simplest R object type is the vector, which is an ordered list of components of the same kind. Component can be numeric, complex, character, logical, NA and others. Vectors have the mode property, where mode can be numeric, complex, character, logical and others. You use the mode() function to obtain access to the mode property. The other property of vectors is the length, or the number of components, and it can be accessed through the length() function. The names property is also supported. names property is a vector itself and gives each component a name. Components can be referred to by either integer indexes or their names.
Basic Data Type: Factor
Factor is an vector object with the levels property. Property levels is a vector of unique values of the original vector. This give those values an order.
R objects also have a property called class. The class of a vector is simply its mode. The class of a Factor is 'factor'. The class property can be accessed via class() function.
Basic Data Type: Array
Array is an vector object with dim property. The dim is a positive integer vector. The component of the dim vector specifies the size of each dimension. Matrix is an array of two dimensions. The mode of an array is the same as the mode of its component. The class of an array is 'array'. Array can be created by combining vectors or by setting a vector's dim property.
Basic Data Type: List
By combing objects of different type in an ordered list, we created a list object. List object can have a names property that is a vector of mode character and it gives each list-component a name. List objects have the class property set to 'list'.
Basic Data Type: data.frame
data.frame object is considered as an extension of list object with restrictions placed on the size of the list-component so that the data.frame resemble a table like structure with each column has the same number of values. These list-components can be vectors, factors, matrix or lists. data.frame have the class of 'data.frame'.
Useful Function/Operators
Environmental
getwd(), setwd(), objects(), ls(), library()
Constructors
Bgn:End (colon), c(), vector(), factor(), list(), data.frame(), matrix(), cbind(), rbind(), matrix()
Casting
as.vector(), as.factor() ...
Indexing
- [] return the same type
- Vctr[ NdxVctr ], Vctr[ NmsVctr ], Vctr[ LgcVctr ] ...
- Mtrx[ NdxVctr1 ][ NdxVctr2 ] ...
- [[ Ndx ]] == $ return the component.
Other
assign(), <-, ->, grep(), function(), tapply(), is.na(), is.vector(), summary(), names()
& (element-wise), | (element-wise), &&, ||
Control Structure
- if (Exp1) Exp2 else Exp3
- ifelse( LgcVctr, TrVctr, FlsVctr) return a vector with components from TrVctr and FlsVctr based on LgcVctr
- for ( Ndx in Vctr) { Expr... }
- while (Cndtn) { Expr ... }
- break
- Vrbl <- function (Arg1, Arg2, ...) { Expr ... }
Sunday, March 14, 2010
News feeds to China public
According to the news, Google could retreated from China as soon as the end of March, 2010. Recently, I read a news article that I feel it really worth reading for all the Chinese people including people lived in Taiwan and I begin to think how can I help feed news to Chinese lived inside China's Great Firewall.
I am sorry to say that "Bill Gates, I do not agree with you on that there are a lot of (technical) ways that Chinese people can reach the outside world". I believe they need help. One thing I hope can be done is to defeat the filtering of search result. Here are some of my idea.
1. Create sites with China-Communist Party permissible articles so that it can be indexed. We will then provide CAPTCHA and allow users to view the unfiltered result - possibly from Google.
2. Encourage everyone that care about this issue to setup various web sites so that it become extremely expensive for China-Communist to filter all these sites.
Comments welcome. I believe there are a lot of smart people that can provide even better ideas like dynamically register new sites from time to time.
I am sorry to say that "Bill Gates, I do not agree with you on that there are a lot of (technical) ways that Chinese people can reach the outside world". I believe they need help. One thing I hope can be done is to defeat the filtering of search result. Here are some of my idea.
1. Create sites with China-Communist Party permissible articles so that it can be indexed. We will then provide CAPTCHA and allow users to view the unfiltered result - possibly from Google.
2. Encourage everyone that care about this issue to setup various web sites so that it become extremely expensive for China-Communist to filter all these sites.
Comments welcome. I believe there are a lot of smart people that can provide even better ideas like dynamically register new sites from time to time.
Monday, February 15, 2010
Youtube Flash Video download with Firefox
Firefox add-on: Download Flash and Video is a very nice add-on.
Once you installed the add-on, you will see a downward arrow on the lower-right side of the browser window. If you are on a web page, clicking on the arrow will show a list of flash sources on the page. If you mouse over an item, the source on the web page will be highlighted. You can save the .swf file directly or you can start the video and re-click the arrow to download the .flv files.
Once you have the video saved, you will need a player to view the video.
Once you installed the add-on, you will see a downward arrow on the lower-right side of the browser window. If you are on a web page, clicking on the arrow will show a list of flash sources on the page. If you mouse over an item, the source on the web page will be highlighted. You can save the .swf file directly or you can start the video and re-click the arrow to download the .flv files.
Once you have the video saved, you will need a player to view the video.
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