log2 ValueError: math domain error while trying to find entropy

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So I'm trying to make a fucntion, that will find D (I don't know english word for it) for text with H (entropy). But getting an error with next code

symbol_dict- is a dictonary with alphabet symbols as keys and how much script meets symbol in text, lang_x it's list of needed alphabet symbols (same as keys in dictonary)

def emk_otn_f(symbol_dict, lang_x):

    from math import log2

    total = 0

    entropy = 0

    entropy_max = 0

    for i in range(len(symbol_dict)):  # Here I'm count the sum of all symbols in text

        symbol = lang_x[i]

        total = total + symbol_dict[symbol]

    for i in range(len(symbol_dict)):  # Here I'm trying to find an entropy with formula (-Sigma... etc.)

        symbol = lang_x[i]

        entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total)

    entropy = entropy * (-1)

    for i in range(len(symbol_dict)):  #max Entropy

        entropy_max = entropy_max + (1/total * log2(1/total))

    entropy_max = entropy_max * (-1)

    emk = entropy_max - entropy  

    emk_otn = (emk/entropy_max) * 100 

    return emk_otn

But the only thing i'm see after execution is:

File "formula.py", line 11, in emk_otn_f entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) ValueError: math domain error

After googling and testing I finded out that:

(symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) is not working

(symbol_dict[symbol] / total) have legit-like values (I was printing them in cycle for)

log2(symbol_dict[symbol] / total) gives the same error
But I don't see any problem with log2, and it looks legit for me.

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

1

Did you precede that problem line with print(symbol_dict[symbol], total) to see if symbol_dict[symbol] is zero or negative or total is negative? The log2 function from the math unit handles only positive numbers and gives your error for zero or negative numbers.
– Rory Daulton
Nov 11 at 19:24

@RoryDaulton I checked it now, but it seems they both positive. But at the end of output (after executing it for some text) there is None I guess problem can be in this one. I will try to change for to while and count from -1 to len()
– Pavel Konstantinov
Nov 12 at 3:45

add a comment |

up vote
-1
down vote

favorite

So I'm trying to make a fucntion, that will find D (I don't know english word for it) for text with H (entropy). But getting an error with next code

symbol_dict- is a dictonary with alphabet symbols as keys and how much script meets symbol in text, lang_x it's list of needed alphabet symbols (same as keys in dictonary)

def emk_otn_f(symbol_dict, lang_x):

    from math import log2

    total = 0

    entropy = 0

    entropy_max = 0

    for i in range(len(symbol_dict)):  # Here I'm count the sum of all symbols in text

        symbol = lang_x[i]

        total = total + symbol_dict[symbol]

    for i in range(len(symbol_dict)):  # Here I'm trying to find an entropy with formula (-Sigma... etc.)

        symbol = lang_x[i]

        entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total)

    entropy = entropy * (-1)

    for i in range(len(symbol_dict)):  #max Entropy

        entropy_max = entropy_max + (1/total * log2(1/total))

    entropy_max = entropy_max * (-1)

    emk = entropy_max - entropy  

    emk_otn = (emk/entropy_max) * 100 

    return emk_otn

But the only thing i'm see after execution is:

File "formula.py", line 11, in emk_otn_f entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) ValueError: math domain error

After googling and testing I finded out that:

(symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) is not working

(symbol_dict[symbol] / total) have legit-like values (I was printing them in cycle for)

log2(symbol_dict[symbol] / total) gives the same error
But I don't see any problem with log2, and it looks legit for me.

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

1

Did you precede that problem line with print(symbol_dict[symbol], total) to see if symbol_dict[symbol] is zero or negative or total is negative? The log2 function from the math unit handles only positive numbers and gives your error for zero or negative numbers.
– Rory Daulton
Nov 11 at 19:24

@RoryDaulton I checked it now, but it seems they both positive. But at the end of output (after executing it for some text) there is None I guess problem can be in this one. I will try to change for to while and count from -1 to len()
– Pavel Konstantinov
Nov 12 at 3:45

add a comment |

up vote
-1
down vote

favorite

So I'm trying to make a fucntion, that will find D (I don't know english word for it) for text with H (entropy). But getting an error with next code

symbol_dict- is a dictonary with alphabet symbols as keys and how much script meets symbol in text, lang_x it's list of needed alphabet symbols (same as keys in dictonary)

def emk_otn_f(symbol_dict, lang_x):

    from math import log2

    total = 0

    entropy = 0

    entropy_max = 0

    for i in range(len(symbol_dict)):  # Here I'm count the sum of all symbols in text

        symbol = lang_x[i]

        total = total + symbol_dict[symbol]

    for i in range(len(symbol_dict)):  # Here I'm trying to find an entropy with formula (-Sigma... etc.)

        symbol = lang_x[i]

        entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total)

    entropy = entropy * (-1)

    for i in range(len(symbol_dict)):  #max Entropy

        entropy_max = entropy_max + (1/total * log2(1/total))

    entropy_max = entropy_max * (-1)

    emk = entropy_max - entropy  

    emk_otn = (emk/entropy_max) * 100 

    return emk_otn

But the only thing i'm see after execution is:

File "formula.py", line 11, in emk_otn_f entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) ValueError: math domain error

After googling and testing I finded out that:

(symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) is not working

(symbol_dict[symbol] / total) have legit-like values (I was printing them in cycle for)

log2(symbol_dict[symbol] / total) gives the same error
But I don't see any problem with log2, and it looks legit for me.

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

So I'm trying to make a fucntion, that will find D (I don't know english word for it) for text with H (entropy). But getting an error with next code

symbol_dict- is a dictonary with alphabet symbols as keys and how much script meets symbol in text, lang_x it's list of needed alphabet symbols (same as keys in dictonary)

def emk_otn_f(symbol_dict, lang_x):

    from math import log2

    total = 0

    entropy = 0

    entropy_max = 0

    for i in range(len(symbol_dict)):  # Here I'm count the sum of all symbols in text

        symbol = lang_x[i]

        total = total + symbol_dict[symbol]

    for i in range(len(symbol_dict)):  # Here I'm trying to find an entropy with formula (-Sigma... etc.)

        symbol = lang_x[i]

        entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total)

    entropy = entropy * (-1)

    for i in range(len(symbol_dict)):  #max Entropy

        entropy_max = entropy_max + (1/total * log2(1/total))

    entropy_max = entropy_max * (-1)

    emk = entropy_max - entropy  

    emk_otn = (emk/entropy_max) * 100 

    return emk_otn

But the only thing i'm see after execution is:

File "formula.py", line 11, in emk_otn_f entropy = entropy + (symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) ValueError: math domain error

After googling and testing I finded out that:

(symbol_dict[symbol] / total) * log2(symbol_dict[symbol] / total) is not working

(symbol_dict[symbol] / total) have legit-like values (I was printing them in cycle for)

log2(symbol_dict[symbol] / total) gives the same error
But I don't see any problem with log2, and it looks legit for me.

python python-3.x math

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

edited Nov 11 at 19:23

martineau

65.1k987176

edited Nov 11 at 19:23

martineau

65.1k987176

edited Nov 11 at 19:23

martineau

65.1k987176

asked Nov 11 at 19:17

Pavel Konstantinov

asked Nov 11 at 19:17

Pavel Konstantinov

asked Nov 11 at 19:17

Pavel Konstantinov

1

Did you precede that problem line with print(symbol_dict[symbol], total) to see if symbol_dict[symbol] is zero or negative or total is negative? The log2 function from the math unit handles only positive numbers and gives your error for zero or negative numbers.
– Rory Daulton
Nov 11 at 19:24

@RoryDaulton I checked it now, but it seems they both positive. But at the end of output (after executing it for some text) there is None I guess problem can be in this one. I will try to change for to while and count from -1 to len()
– Pavel Konstantinov
Nov 12 at 3:45

add a comment |

1

Did you precede that problem line with print(symbol_dict[symbol], total) to see if symbol_dict[symbol] is zero or negative or total is negative? The log2 function from the math unit handles only positive numbers and gives your error for zero or negative numbers.
– Rory Daulton
Nov 11 at 19:24

@RoryDaulton I checked it now, but it seems they both positive. But at the end of output (after executing it for some text) there is None I guess problem can be in this one. I will try to change for to while and count from -1 to len()
– Pavel Konstantinov
Nov 12 at 3:45

Did you precede that problem line with print(symbol_dict[symbol], total) to see if symbol_dict[symbol] is zero or negative or total is negative? The log2 function from the math unit handles only positive numbers and gives your error for zero or negative numbers.
– Rory Daulton
Nov 11 at 19:24

@RoryDaulton I checked it now, but it seems they both positive. But at the end of output (after executing it for some text) there is None I guess problem can be in this one. I will try to change for to while and count from -1 to len()
– Pavel Konstantinov
Nov 12 at 3:45

add a comment |

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