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Itertools, Numbers, Combinatorics, OS Commands
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‎README.md

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@@ -200,23 +200,23 @@ Iterator
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### Itertools
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```python
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from itertools import count, repeat, cycle, chain, islice
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import itertools as it
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```
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```python
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<iter> = count(start=0, step=1) # Returns updated value endlessly. Accepts floats.
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<iter> = repeat(<el> [, times]) # Returns element endlessly or 'times' times.
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<iter> = cycle(<collection>) # Repeats the sequence endlessly.
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<iter> = it.count(start=0, step=1) # Returns updated value endlessly. Accepts floats.
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<iter> = it.repeat(<el> [, times]) # Returns element endlessly or 'times' times.
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<iter> = it.cycle(<collection>) # Repeats the sequence endlessly.
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```
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```python
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<iter> = chain(<coll_1>, <coll_2> [, ...]) # Empties collections in order (figuratively).
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<iter> = chain.from_iterable(<coll>) # Empties collections inside a collection in order.
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<iter> = it.chain(<coll>, <coll> [, ...]) # Empties collections in order (figuratively).
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<iter> = it.chain.from_iterable(<coll>) # Empties collections inside a collection in order.
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```
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```python
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<iter> = islice(<coll>, to_exclusive) # Only returns first 'to_exclusive' elements.
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<iter> = islice(<coll>, from_inclusive, …) # `to_exclusive, +step_size`. Indices can be None.
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<iter> = it.islice(<coll>, to_exclusive) # Only returns first 'to_exclusive' elements.
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<iter> = it.islice(<coll>, from_inc, …) # `to_exclusive, +step_size`. Indices can be None.
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```
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@@ -486,11 +486,11 @@ Format
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Numbers
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-------
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```python
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<int> = int(<float/str/bool>) # Or: math.floor(<float>)
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<float> = float(<int/str/bool>) # Or: <real>e±<int>
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<complex> = complex(real=0, imag=0) # Or: <real> ± <real>j
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<Fraction> = fractions.Fraction(0, 1) # Or: Fraction(numerator=0, denominator=1)
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<Decimal> = decimal.Decimal(<str/int>) # Or: Decimal((sign, digits, exponent))
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<int> = int(<float/str/bool>) # Or: math.floor(<float>)
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<float> = float(<int/str/bool>) # Or: <real>e±<int>
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<complex> = complex(real=0, imag=0) # Or: <real> ± <real>j
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<Fraction> = fractions.Fraction(0, 1) # Or: Fraction(numerator=0, denominator=1)
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<Decimal> = decimal.Decimal(<str/int>) # Or: Decimal((sign, digits, exponent))
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```
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* **`'int(<str>)'` and `'float(<str>)'` raise ValueError on malformed strings.**
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* **Decimal numbers are stored exactly, unlike most floats where `'1.1 + 2.2 != 3.3'`.**
@@ -499,47 +499,46 @@ Numbers
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### Basic Functions
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```python
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<num> = pow(<num>, <num>) # Or: <num> ** <num>
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<num> = abs(<num>) # <float> = abs(<complex>)
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<num> = round(<num> [, ±ndigits]) # `round(126, -1) == 130`
502+
<num> = pow(<num>, <num>) # Or: <num> ** <num>
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<num> = abs(<num>) # <float> = abs(<complex>)
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<num> = round(<num> [, ±ndigits]) # `round(126, -1) == 130`
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```
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### Math
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```python
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from math import e, pi, inf, nan, isinf, isnan
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from math import sin, cos, tan, asin, acos, atan, degrees, radians
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from math import log, log10, log2
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from math import e, pi, inf, nan, isinf, isnan # `<el> == nan` is always False.
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from math import sin, cos, tan, asin, acos, atan # Also: degrees, radians.
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from math import log, log10, log2 # Log can accept base as second arg.
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```
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### Statistics
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```python
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from statistics import mean, median, variance, stdev, quantiles, groupby
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from statistics import mean, median, variance # Also: stdev, quantiles, groupby.
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```
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### Random
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```python
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from random import random, randint, choice, shuffle, gauss, seed
522-
523-
<float> = random() # A float inside [0, 1).
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<int> = randint(from_inc, to_inc) # An int inside [from_inc, to_inc].
525-
<el> = choice(<sequence>) # Keeps the sequence intact.
521+
from random import random, randint, choice # Also shuffle, gauss, triangular, seed.
522+
<float> = random() # A float inside [0, 1).
523+
<int> = randint(from_inc, to_inc) # An int inside [from_inc, to_inc].
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<el> = choice(<sequence>) # Keeps the sequence intact.
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```
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### Bin, Hex
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```python
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<int> = ±0b<bin> # Or: ±0x<hex>
531-
<int> = int('±<bin>', 2) # Or: int('±<hex>', 16)
532-
<int> = int('±0b<bin>', 0) # Or: int('±0x<hex>', 0)
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<str> = bin(<int>) # Returns '[-]0b<bin>'.
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<int> = ±0b<bin> # Or: ±0x<hex>
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<int> = int('±<bin>', 2) # Or: int('±<hex>', 16)
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<int> = int('±0b<bin>', 0) # Or: int('±0x<hex>', 0)
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<str> = bin(<int>) # Returns '[-]0b<bin>'.
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```
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### Bitwise Operators
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```python
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<int> = <int> & <int> # And (0b1100 & 0b1010 == 0b1000).
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<int> = <int> | <int> # Or (0b1100 | 0b1010 == 0b1110).
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<int> = <int> ^ <int> # Xor (0b1100 ^ 0b1010 == 0b0110).
541-
<int> = <int> << n_bits # Left shift. Use >> for right.
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<int> = ~<int> # Not. Also -<int> - 1.
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<int> = <int> & <int> # And (0b1100 & 0b1010 == 0b1000).
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<int> = <int> | <int> # Or (0b1100 | 0b1010 == 0b1110).
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<int> = <int> ^ <int> # Xor (0b1100 ^ 0b1010 == 0b0110).
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<int> = <int> << n_bits # Left shift. Use >> for right.
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<int> = ~<int> # Not. Also -<int> - 1.
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```
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@@ -549,39 +548,40 @@ Combinatorics
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* **If you want to print the iterator, you need to pass it to the list() function first!**
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```python
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from itertools import product, combinations, combinations_with_replacement, permutations
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import itertools as it
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```
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```python
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>>> product([0, 1], repeat=3)
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[(0, 0, 0), (0, 0, 1), (0, 1, 0), (0, 1, 1), ..., (1, 1, 1)]
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>>> it.product([0, 1], repeat=3)
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[(0, 0, 0), (0, 0, 1), (0, 1, 0), (0, 1, 1),
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(1, 0, 0), (1, 0, 1), (1, 1, 0), (1, 1, 1)]
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```
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```python
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>>> product('abc', 'abc') # a b c
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[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
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('b', 'a'), ('b', 'b'), ('b', 'c'), # b x x x
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('c', 'a'), ('c', 'b'), ('c', 'c')] # c x x x
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>>> it.product('abc', 'abc') # a b c
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[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
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('b', 'a'), ('b', 'b'), ('b', 'c'), # b x x x
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('c', 'a'), ('c', 'b'), ('c', 'c')] # c x x x
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```
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```python
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>>> combinations('abc', 2) # a b c
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[('a', 'b'), ('a', 'c'), # a . x x
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('b', 'c')] # b . . x
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>>> it.combinations('abc', 2) # a b c
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[('a', 'b'), ('a', 'c'), # a . x x
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('b', 'c')] # b . . x
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```
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```python
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>>> combinations_with_replacement('abc', 2) # a b c
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[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
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('b', 'b'), ('b', 'c'), # b . x x
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('c', 'c')] # c . . x
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>>> it.combinations_with_replacement('abc', 2) # a b c
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[('a', 'a'), ('a', 'b'), ('a', 'c'), # a x x x
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('b', 'b'), ('b', 'c'), # b . x x
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('c', 'c')] # c . . x
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```
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```python
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>>> permutations('abc', 2) # a b c
582-
[('a', 'b'), ('a', 'c'), # a . x x
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('b', 'a'), ('b', 'c'), # b x . x
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('c', 'a'), ('c', 'b')] # c x x .
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>>> it.permutations('abc', 2) # a b c
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[('a', 'b'), ('a', 'c'), # a . x x
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('b', 'a'), ('b', 'c'), # b x . x
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('c', 'a'), ('c', 'b')] # c x x .
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```
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@@ -1701,34 +1701,34 @@ import os, shutil, subprocess
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```
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```python
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os.chdir(<path>) # Changes the current working directory.
1705-
os.mkdir(<path>, mode=0o777) # Creates a directory. Mode is in octal.
1706-
os.makedirs(<path>, mode=0o777) # Creates all path's dirs. Also: `exist_ok=False`.
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os.chdir(<path>) # Changes the current working directory.
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os.mkdir(<path>, mode=0o777) # Creates a directory. Permissions are in octal.
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os.makedirs(<path>, mode=0o777) # Creates all path's dirs. Also: `exist_ok=False`.
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```
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```python
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shutil.copy(from, to) # Copies the file. 'to' can exist or be a dir.
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shutil.copytree(from, to) # Copies the directory. 'to' must not exist.
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shutil.copy(from, to) # Copies the file. 'to' can exist or be a dir.
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shutil.copytree(from, to) # Copies the directory. 'to' must not exist.
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```
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```python
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os.rename(from, to) # Renames/moves the file or directory.
1716-
os.replace(from, to) # Same, but overwrites 'to' if it exists.
1715+
os.rename(from, to) # Renames/moves the file or directory.
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os.replace(from, to) # Same, but overwrites 'to' if it exists.
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```
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```python
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os.remove(<path>) # Deletes the file.
1721-
os.rmdir(<path>) # Deletes the empty directory.
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shutil.rmtree(<path>) # Deletes the directory.
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os.remove(<path>) # Deletes the file.
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os.rmdir(<path>) # Deletes the empty directory.
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shutil.rmtree(<path>) # Deletes the directory.
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```
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* **Paths can be either strings, Paths or DirEntry objects.**
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* **Functions report OS related errors by raising either OSError or one of its [subclasses](#exceptions-1).**
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### Shell Commands
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```python
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<pipe> = os.popen('<command>') # Executes command in sh/cmd and returns its stdout pipe.
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<str> = <pipe>.read(size=-1) # Reads 'size' chars or until EOF. Also readline/s().
1731-
<int> = <pipe>.close() # Closes the pipe. Returns None on success, int on error.
1729+
<pipe> = os.popen('<command>') # Executes command in sh/cmd. Returns its stdout pipe.
1730+
<str> = <pipe>.read(size=-1) # Reads 'size' chars or until EOF. Also readline/s().
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<int> = <pipe>.close() # Closes the pipe. Returns None on success.
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```
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#### Sends '1 + 1' to the basic calculator and captures its output:
@@ -1754,8 +1754,8 @@ JSON
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```python
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import json
1757-
<str> = json.dumps(<object>) # Converts object to JSON string.
1758-
<object> = json.loads(<str>) # Converts JSON string to object.
1757+
<str> = json.dumps(<object>) # Converts object to JSON string.
1758+
<object> = json.loads(<str>) # Converts JSON string to object.
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```
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### Read Object from JSON File
@@ -1779,8 +1779,8 @@ Pickle
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```python
17811781
import pickle
1782-
<bytes> = pickle.dumps(<object>) # Converts object to bytes object.
1783-
<object> = pickle.loads(<bytes>) # Converts bytes object to object.
1782+
<bytes> = pickle.dumps(<object>) # Converts object to bytes object.
1783+
<object> = pickle.loads(<bytes>) # Converts bytes object to object.
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```
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### Read Object from File

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