Package moa.core
Class Utils
- java.lang.Object
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- moa.core.Utils
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public final class Utils extends Object
Class implementing some simple utility methods.- Version:
- $Revision: 8080 $
- Author:
- Eibe Frank, Yong Wang, Len Trigg, Julien Prados
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Constructor Summary
Constructors Constructor Description Utils()
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Method Summary
All Methods Static Methods Concrete Methods Modifier and Type Method Description static String
arrayToString(Object array)
Returns the given Array in a string representation.static String
backQuoteChars(String string)
Converts carriage returns and new lines in a string into \r and \n.static String[]
breakUp(String s, int columns)
Breaks up the string, if wider than "columns" characters.static <T> T
cast(Object x)
Casting an object without "unchecked" compile-time warnings.static void
checkForRemainingOptions(String[] options)
Checks if the given array contains any non-empty options.static String
convertNewLines(String string)
Converts carriage returns and new lines in a string into \r and \n.static File
convertToRelativePath(File absolute)
Converts a File's absolute path to a path relative to the user (ie start) directory.static double
correlation(double[] y1, double[] y2, int n)
Returns the correlation coefficient of two double vectors.protected static File
createRelativePath(File absolute)
Converts a File's absolute path to a path relative to the user (ie start) directory.static String
doubleToString(double value, int afterDecimalPoint)
Rounds a double and converts it into String.static String
doubleToString(double value, int width, int afterDecimalPoint)
Rounds a double and converts it into a formatted decimal-justified String.static boolean
eq(double a, double b)
Tests if a is equal to b.static Object
forName(Class<?> classType, String className, String[] options)
Creates a new instance of an object given it's class name and (optional) arguments to pass to it's setOptions method.static Class
getArrayClass(Class c)
Returns the basic class of an array class (handles multi-dimensional arrays).static int
getArrayDimensions(Class array)
Returns the dimensions of the given array.static int
getArrayDimensions(Object array)
Returns the dimensions of the given array.static boolean
getFlag(char flag, String[] options)
Checks if the given array contains the flag "-Char".static boolean
getFlag(String flag, String[] options)
Checks if the given array contains the flag "-String".static String
getOption(char flag, String[] options)
Gets an option indicated by a flag "-Char" from the given array of strings.static String
getOption(String flag, String[] options)
Gets an option indicated by a flag "-String" from the given array of strings.static int
getOptionPos(char flag, String[] options)
Gets the index of an option or flag indicated by a flag "-Char" from the given array of strings.static int
getOptionPos(String flag, String[] options)
Gets the index of an option or flag indicated by a flag "-String" from the given array of strings.static boolean
gr(double a, double b)
Tests if a is greater than b.static boolean
grOrEq(double a, double b)
Tests if a is greater or equal to b.static double
info(int[] counts)
Computes entropy for an array of integers.static boolean
isMissingValue(double val)
Tests if the given value codes "missing".static String
joinOptions(String[] optionArray)
Joins all the options in an option array into a single string, as might be used on the command line.static double
kthSmallestValue(double[] array, int k)
Returns the kth-smallest value in the arraystatic double
kthSmallestValue(int[] array, int k)
Returns the kth-smallest value in the array.static double
log2(double a)
Returns the logarithm of a for base 2.static double[]
logs2probs(double[] a)
Converts an array containing the natural logarithms of probabilities stored in a vector back into probabilities.static int
maxIndex(double[] doubles)
Returns index of maximum element in a given array of doubles.static int
maxIndex(int[] ints)
Returns index of maximum element in a given array of integers.static double
mean(double[] vector)
Computes the mean for an array of doubles.static int
minIndex(double[] doubles)
Returns index of minimum element in a given array of doubles.static int
minIndex(int[] ints)
Returns index of minimum element in a given array of integers.static double
missingValue()
Returns the value used to code a missing value.static void
normalize(double[] doubles)
Normalizes the doubles in the array by their sum.static void
normalize(double[] doubles, double sum)
Normalizes the doubles in the array using the given value.static String
padLeft(String inString, int length)
Pads a string to a specified length, inserting spaces on the left as required.static String
padRight(String inString, int length)
Pads a string to a specified length, inserting spaces on the right as required.static String[]
partitionOptions(String[] options)
Returns the secondary set of options (if any) contained in the supplied options array.static int
probRound(double value, Random rand)
Rounds a double to the next nearest integer value in a probabilistic fashion (e.g.static double
probToLogOdds(double prob)
Returns the log-odds for a given probabilitiy.static String
quote(String string)
Quotes a string if it contains special characters.static String
removeSubstring(String inString, String substring)
Removes all occurrences of a string from another string.static String
replaceSubstring(String inString, String subString, String replaceString)
Replaces with a new string, all occurrences of a string from another string.static String
revertNewLines(String string)
Reverts \r and \n in a string into carriage returns and new lines.static int
round(double value)
Rounds a double to the next nearest integer value.static double
roundDouble(double value, int afterDecimalPoint)
Rounds a double to the given number of decimal places.static boolean
sm(double a, double b)
Tests if a is smaller than b.static boolean
smOrEq(double a, double b)
Tests if a is smaller or equal to b.static int[]
sort(double[] array)
Sorts a given array of doubles in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array.static int[]
sort(int[] array)
Sorts a given array of integers in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array.static String[]
splitOptions(String quotedOptionString)
Split up a string containing options into an array of strings, one for each option.static int[]
stableSort(double[] array)
Sorts a given array of doubles in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array.static double
sum(double[] doubles)
Computes the sum of the elements of an array of doubles.static int
sum(int[] ints)
Computes the sum of the elements of an array of integers.static String
unbackQuoteChars(String string)
The inverse operation of backQuoteChars().static String
unquote(String string)
unquotes are previously quoted string (but only if necessary), i.e., it removes the single quotes around it.static double
variance(double[] vector)
Computes the variance for an array of doubles.static double
xlogx(int c)
Returns c*log2(c) for a given integer value c.
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Method Detail
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isMissingValue
public static boolean isMissingValue(double val)
Tests if the given value codes "missing".- Parameters:
val
- the value to be tested- Returns:
- true if val codes "missing"
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missingValue
public static double missingValue()
Returns the value used to code a missing value. Note that equality tests on this value will always return false, so use isMissingValue(double val) for testing..- Returns:
- the value used as missing value.
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cast
public static <T> T cast(Object x)
Casting an object without "unchecked" compile-time warnings. Use only when absolutely necessary (e.g. when using clone()).
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correlation
public static final double correlation(double[] y1, double[] y2, int n)
Returns the correlation coefficient of two double vectors.- Parameters:
y1
- double vector 1y2
- double vector 2n
- the length of two double vectors- Returns:
- the correlation coefficient
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removeSubstring
public static String removeSubstring(String inString, String substring)
Removes all occurrences of a string from another string.- Parameters:
inString
- the string to remove substrings from.substring
- the substring to remove.- Returns:
- the input string with occurrences of substring removed.
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replaceSubstring
public static String replaceSubstring(String inString, String subString, String replaceString)
Replaces with a new string, all occurrences of a string from another string.- Parameters:
inString
- the string to replace substrings in.subString
- the substring to replace.replaceString
- the replacement substring- Returns:
- the input string with occurrences of substring replaced.
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padLeft
public static String padLeft(String inString, int length)
Pads a string to a specified length, inserting spaces on the left as required. If the string is too long, characters are removed (from the right).- Parameters:
inString
- the input stringlength
- the desired length of the output string- Returns:
- the output string
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padRight
public static String padRight(String inString, int length)
Pads a string to a specified length, inserting spaces on the right as required. If the string is too long, characters are removed (from the right).- Parameters:
inString
- the input stringlength
- the desired length of the output string- Returns:
- the output string
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doubleToString
public static String doubleToString(double value, int afterDecimalPoint)
Rounds a double and converts it into String.- Parameters:
value
- the double valueafterDecimalPoint
- the (maximum) number of digits permitted after the decimal point- Returns:
- the double as a formatted string
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doubleToString
public static String doubleToString(double value, int width, int afterDecimalPoint)
Rounds a double and converts it into a formatted decimal-justified String. Trailing 0's are replaced with spaces.- Parameters:
value
- the double valuewidth
- the width of the stringafterDecimalPoint
- the number of digits after the decimal point- Returns:
- the double as a formatted string
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getArrayClass
public static Class getArrayClass(Class c)
Returns the basic class of an array class (handles multi-dimensional arrays).- Parameters:
c
- the array to inspect- Returns:
- the class of the innermost elements
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getArrayDimensions
public static int getArrayDimensions(Class array)
Returns the dimensions of the given array. Even though the parameter is of type "Object" one can hand over primitve arrays, e.g. int[3] or double[2][4].- Parameters:
array
- the array to determine the dimensions for- Returns:
- the dimensions of the array
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getArrayDimensions
public static int getArrayDimensions(Object array)
Returns the dimensions of the given array. Even though the parameter is of type "Object" one can hand over primitve arrays, e.g. int[3] or double[2][4].- Parameters:
array
- the array to determine the dimensions for- Returns:
- the dimensions of the array
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arrayToString
public static String arrayToString(Object array)
Returns the given Array in a string representation. Even though the parameter is of type "Object" one can hand over primitve arrays, e.g. int[3] or double[2][4].- Parameters:
array
- the array to return in a string representation- Returns:
- the array as string
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eq
public static boolean eq(double a, double b)
Tests if a is equal to b.- Parameters:
a
- a doubleb
- a double
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checkForRemainingOptions
public static void checkForRemainingOptions(String[] options) throws Exception
Checks if the given array contains any non-empty options.- Parameters:
options
- an array of strings- Throws:
Exception
- if there are any non-empty options
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getFlag
public static boolean getFlag(char flag, String[] options) throws Exception
Checks if the given array contains the flag "-Char". Stops searching at the first marker "--". If the flag is found, it is replaced with the empty string.- Parameters:
flag
- the character indicating the flag.options
- the array of strings containing all the options.- Returns:
- true if the flag was found
- Throws:
Exception
- if an illegal option was found
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getFlag
public static boolean getFlag(String flag, String[] options) throws Exception
Checks if the given array contains the flag "-String". Stops searching at the first marker "--". If the flag is found, it is replaced with the empty string.- Parameters:
flag
- the String indicating the flag.options
- the array of strings containing all the options.- Returns:
- true if the flag was found
- Throws:
Exception
- if an illegal option was found
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getOption
public static String getOption(char flag, String[] options) throws Exception
Gets an option indicated by a flag "-Char" from the given array of strings. Stops searching at the first marker "--". Replaces flag and option with empty strings.- Parameters:
flag
- the character indicating the option.options
- the array of strings containing all the options.- Returns:
- the indicated option or an empty string
- Throws:
Exception
- if the option indicated by the flag can't be found
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getOption
public static String getOption(String flag, String[] options) throws Exception
Gets an option indicated by a flag "-String" from the given array of strings. Stops searching at the first marker "--". Replaces flag and option with empty strings.- Parameters:
flag
- the String indicating the option.options
- the array of strings containing all the options.- Returns:
- the indicated option or an empty string
- Throws:
Exception
- if the option indicated by the flag can't be found
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getOptionPos
public static int getOptionPos(char flag, String[] options)
Gets the index of an option or flag indicated by a flag "-Char" from the given array of strings. Stops searching at the first marker "--".- Parameters:
flag
- the character indicating the option.options
- the array of strings containing all the options.- Returns:
- the position if found, or -1 otherwise
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getOptionPos
public static int getOptionPos(String flag, String[] options)
Gets the index of an option or flag indicated by a flag "-String" from the given array of strings. Stops searching at the first marker "--".- Parameters:
flag
- the String indicating the option.options
- the array of strings containing all the options.- Returns:
- the position if found, or -1 otherwise
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quote
public static String quote(String string)
Quotes a string if it contains special characters. The following rules are applied: A character is backquoted version of it is one of " ' % \ \n \r \t. A string is enclosed within single quotes if a character has been backquoted using the previous rule above or contains { } or is exactly equal to the strings , ? space or "" (empty string). A quoted question mark distinguishes it from the missing value which is represented as an unquoted question mark in arff files.- Parameters:
string
- the string to be quoted- Returns:
- the string (possibly quoted)
- See Also:
unquote(String)
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unquote
public static String unquote(String string)
unquotes are previously quoted string (but only if necessary), i.e., it removes the single quotes around it. Inverse to quote(String).- Parameters:
string
- the string to process- Returns:
- the unquoted string
- See Also:
quote(String)
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backQuoteChars
public static String backQuoteChars(String string)
Converts carriage returns and new lines in a string into \r and \n. Backquotes the following characters: ` " \ \t and %- Parameters:
string
- the string- Returns:
- the converted string
- See Also:
unbackQuoteChars(String)
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convertNewLines
public static String convertNewLines(String string)
Converts carriage returns and new lines in a string into \r and \n.- Parameters:
string
- the string- Returns:
- the converted string
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revertNewLines
public static String revertNewLines(String string)
Reverts \r and \n in a string into carriage returns and new lines.- Parameters:
string
- the string- Returns:
- the converted string
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partitionOptions
public static String[] partitionOptions(String[] options)
Returns the secondary set of options (if any) contained in the supplied options array. The secondary set is defined to be any options after the first "--". These options are removed from the original options array.- Parameters:
options
- the input array of options- Returns:
- the array of secondary options
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unbackQuoteChars
public static String unbackQuoteChars(String string)
The inverse operation of backQuoteChars(). Converts back-quoted carriage returns and new lines in a string to the corresponding character ('\r' and '\n'). Also "un"-back-quotes the following characters: ` " \ \t and %- Parameters:
string
- the string- Returns:
- the converted string
- See Also:
backQuoteChars(String)
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splitOptions
public static String[] splitOptions(String quotedOptionString) throws Exception
Split up a string containing options into an array of strings, one for each option.- Parameters:
quotedOptionString
- the string containing the options- Returns:
- the array of options
- Throws:
Exception
- in case of an unterminated string, unknown character or a parse error
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joinOptions
public static String joinOptions(String[] optionArray)
Joins all the options in an option array into a single string, as might be used on the command line.- Parameters:
optionArray
- the array of options- Returns:
- the string containing all options.
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info
public static double info(int[] counts)
Computes entropy for an array of integers.- Parameters:
counts
- array of counts- Returns:
- - a log2 a - b log2 b - c log2 c + (a+b+c) log2 (a+b+c) when given array [a b c]
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smOrEq
public static boolean smOrEq(double a, double b)
Tests if a is smaller or equal to b.- Parameters:
a
- a doubleb
- a double
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grOrEq
public static boolean grOrEq(double a, double b)
Tests if a is greater or equal to b.- Parameters:
a
- a doubleb
- a double
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sm
public static boolean sm(double a, double b)
Tests if a is smaller than b.- Parameters:
a
- a doubleb
- a double
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gr
public static boolean gr(double a, double b)
Tests if a is greater than b.- Parameters:
a
- a doubleb
- a double
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kthSmallestValue
public static double kthSmallestValue(int[] array, int k)
Returns the kth-smallest value in the array.- Parameters:
array
- the array of integersk
- the value of k- Returns:
- the kth-smallest value
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kthSmallestValue
public static double kthSmallestValue(double[] array, int k)
Returns the kth-smallest value in the array- Parameters:
array
- the array of doublek
- the value of k- Returns:
- the kth-smallest value
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log2
public static double log2(double a)
Returns the logarithm of a for base 2.- Parameters:
a
- a double- Returns:
- the logarithm for base 2
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maxIndex
public static int maxIndex(double[] doubles)
Returns index of maximum element in a given array of doubles. First maximum is returned.- Parameters:
doubles
- the array of doubles- Returns:
- the index of the maximum element
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maxIndex
public static int maxIndex(int[] ints)
Returns index of maximum element in a given array of integers. First maximum is returned.- Parameters:
ints
- the array of integers- Returns:
- the index of the maximum element
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mean
public static double mean(double[] vector)
Computes the mean for an array of doubles.- Parameters:
vector
- the array- Returns:
- the mean
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minIndex
public static int minIndex(int[] ints)
Returns index of minimum element in a given array of integers. First minimum is returned.- Parameters:
ints
- the array of integers- Returns:
- the index of the minimum element
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minIndex
public static int minIndex(double[] doubles)
Returns index of minimum element in a given array of doubles. First minimum is returned.- Parameters:
doubles
- the array of doubles- Returns:
- the index of the minimum element
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normalize
public static void normalize(double[] doubles)
Normalizes the doubles in the array by their sum.- Parameters:
doubles
- the array of double- Throws:
IllegalArgumentException
- if sum is Zero or NaN
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normalize
public static void normalize(double[] doubles, double sum)
Normalizes the doubles in the array using the given value.- Parameters:
doubles
- the array of doublesum
- the value by which the doubles are to be normalized- Throws:
IllegalArgumentException
- if sum is zero or NaN
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logs2probs
public static double[] logs2probs(double[] a)
Converts an array containing the natural logarithms of probabilities stored in a vector back into probabilities. The probabilities are assumed to sum to one.- Parameters:
a
- an array holding the natural logarithms of the probabilities- Returns:
- the converted array
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probToLogOdds
public static double probToLogOdds(double prob)
Returns the log-odds for a given probabilitiy.- Parameters:
prob
- the probabilitiy- Returns:
- the log-odds after the probability has been mapped to [Utils.SMALL, 1-Utils.SMALL]
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round
public static int round(double value)
Rounds a double to the next nearest integer value. The JDK version of it doesn't work properly.- Parameters:
value
- the double value- Returns:
- the resulting integer value
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probRound
public static int probRound(double value, Random rand)
Rounds a double to the next nearest integer value in a probabilistic fashion (e.g. 0.8 has a 20% chance of being rounded down to 0 and a 80% chance of being rounded up to 1). In the limit, the average of the rounded numbers generated by this procedure should converge to the original double.- Parameters:
value
- the double valuerand
- the random number generator- Returns:
- the resulting integer value
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roundDouble
public static double roundDouble(double value, int afterDecimalPoint)
Rounds a double to the given number of decimal places.- Parameters:
value
- the double valueafterDecimalPoint
- the number of digits after the decimal point- Returns:
- the double rounded to the given precision
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sort
public static int[] sort(int[] array)
Sorts a given array of integers in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array. The sort is stable. (Equal elements remain in their original order.)- Parameters:
array
- this array is not changed by the method!- Returns:
- an array of integers with the positions in the sorted array.
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sort
public static int[] sort(double[] array)
Sorts a given array of doubles in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array. NOTE THESE CHANGES: the sort is no longer stable and it doesn't use safe floating-point comparisons anymore. Occurrences of Double.NaN are treated as Double.MAX_VALUE- Parameters:
array
- this array is not changed by the method!- Returns:
- an array of integers with the positions in the sorted array.
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stableSort
public static int[] stableSort(double[] array)
Sorts a given array of doubles in ascending order and returns an array of integers with the positions of the elements of the original array in the sorted array. The sort is stable (Equal elements remain in their original order.) Occurrences of Double.NaN are treated as Double.MAX_VALUE- Parameters:
array
- this array is not changed by the method!- Returns:
- an array of integers with the positions in the sorted array.
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variance
public static double variance(double[] vector)
Computes the variance for an array of doubles.- Parameters:
vector
- the array- Returns:
- the variance
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sum
public static double sum(double[] doubles)
Computes the sum of the elements of an array of doubles.- Parameters:
doubles
- the array of double- Returns:
- the sum of the elements
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sum
public static int sum(int[] ints)
Computes the sum of the elements of an array of integers.- Parameters:
ints
- the array of integers- Returns:
- the sum of the elements
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xlogx
public static double xlogx(int c)
Returns c*log2(c) for a given integer value c.- Parameters:
c
- an integer value- Returns:
- c*log2(c) (but is careful to return 0 if c is 0)
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convertToRelativePath
public static File convertToRelativePath(File absolute) throws Exception
Converts a File's absolute path to a path relative to the user (ie start) directory. Includes an additional workaround for Cygwin, which doesn't like upper case drive letters.- Parameters:
absolute
- the File to convert to relative path- Returns:
- a File with a path that is relative to the user's directory
- Throws:
Exception
- if the path cannot be constructed
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createRelativePath
protected static File createRelativePath(File absolute) throws Exception
Converts a File's absolute path to a path relative to the user (ie start) directory.- Parameters:
absolute
- the File to convert to relative path- Returns:
- a File with a path that is relative to the user's directory
- Throws:
Exception
- if the path cannot be constructed
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breakUp
public static String[] breakUp(String s, int columns)
Breaks up the string, if wider than "columns" characters.- Parameters:
s
- the string to processcolumns
- the width in columns- Returns:
- the processed string
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forName
public static Object forName(Class<?> classType, String className, String[] options) throws Exception
Creates a new instance of an object given it's class name and (optional) arguments to pass to it's setOptions method. If the object implements OptionHandler and the options parameter is non-null, the object will have it's options set. Example use:String classifierName = Utils.getOption('W', options); Classifier c = (Classifier)Utils.forName(Classifier.class, classifierName, options); setClassifier(c);
- Parameters:
classType
- the class that the instantiated object should be assignable to -- an exception is thrown if this is not the caseclassName
- the fully qualified class name of the objectoptions
- an array of options suitable for passing to setOptions. May be null. Any options accepted by the object will be removed from the array.- Returns:
- the newly created object, ready for use.
- Throws:
Exception
- if the class name is invalid, or if the class is not assignable to the desired class type, or the options supplied are not acceptable to the object
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