Python Number
To delete the reference to a number object using del. The syntax of the del statement is: del var1[,var2[,var3[....,varN]]]]
Python中不同数据类型之间的转换规则（限number）
1 复数 2 浮点数 3 长整形 4 整形
绝对值函数abs对复数的作用则是 x+yi abs=xX+ yy开平方
Number Type Conversion:
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Type int(x) to convert x to a plain integer.
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Type long(x) to convert x to a long integer.
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Type float(x) to convert x to a floating-point number.
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Type complex(x) to convert x to a complex number with real part x and imaginary part zero.
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Type complex(x, y) to convert x and y to a complex number with real part x and imaginary part y. x and y are numeric expressions
Built-in Number Functions:
Mathematical Functions:
Python includes following functions that perform mathematical calculations.
| Function | Returns ( description ) |
|---|---|
| abs(x) | The absolute value of x: the (positive) distance between x and zero. |
| ceil(x) | The ceiling of x: the smallest integer not less than x |
| cmp(x, y) | -1 if x < y, 0 if x == y, or 1 if x > y |
| exp(x) | The exponential of x: ex |
| fabs(x) | The absolute value of x. |
| floor(x) | The floor of x: the largest integer not greater than x |
| log(x) | The natural logarithm of x, for x> 0 |
| log10(x) | The base-10 logarithm of x for x> 0 . |
| max(x1, x2,...) | The largest of its arguments: the value closest to positive infinity |
| min(x1, x2,...) | The smallest of its arguments: the value closest to negative infinity |
| modf(x) | The fractional and integer parts of x in a two-item tuple. Both parts have the same sign as x. The integer part is returned as a float. |
| pow(x, y) | The value of x**y. |
| round(x [,n]) | x rounded to n digits from the decimal point. Python rounds away from zero as a tie-breaker: round(0.5) is 1.0 and round(-0.5) is -1.0. |
| sqrt(x) | The square root of x for x > 0 |
Random Number Functions:
Random numbers are used for games, simulations, testing, security, and privacy applications. Python includes following functions that are commonly used.
| Function | Returns ( description ) |
|---|---|
| choice(seq) | A random item from a list, tuple, or string. |
| randrange ([start,] stop [,step]) | A randomly selected element from range(start, stop, step) |
| random() | A random float r, such that 0 is less than or equal to r and r is less than 1 |
| seed([x]) | Sets the integer starting value used in generating random numbers. Call this function before calling any other random module function. Returns None. |
| shuffle(lst) | Randomizes the items of a list in place. Returns None. |
| uniform(x, y) | A random float r, such that x is less than or equal to r and r is less than y |
Trigonometric Functions:
Python includes following functions that perform trigonometric calculations.
| Function | Description |
|---|---|
| acos(x) | Return the arc cosine of x, in radians. |
| asin(x) | Return the arc sine of x, in radians. |
| atan(x) | Return the arc tangent of x, in radians. |
| atan2(y, x) | Return atan(y / x), in radians. |
| cos(x) | Return the cosine of x radians. |
| hypot(x, y) | Return the Euclidean norm, sqrt(x*x + y*y). |
| sin(x) | Return the sine of x radians. |
| tan(x) | Return the tangent of x radians. |
| degrees(x) | Converts angle x from radians to degrees. |
| radians(x) | Converts angle x from degrees to radians.转化为弧度 |
Mathematical Constants:
The module also defines two mathematical constants:
| Constant | Description |
|---|---|
| pi | The mathematical constant pi. |
| e | The mathematical constant e. |