Python Programming Cheat Sheet: Essential Syntax and Libraries
Posted on Jun 17, 2026 in Computer Engineering
Numbers and Math
- Arithmetic:
+, -, /, // (floor), % (remainder), ** (exponent). - Shorthand:
a += 2 (also -=, *=, //=). - Functions:
abs(-3.5), round(3.56, 1), max(3.56, 4.57).
Strings and Formatting
- Quotes:
'spam eggs', "doesn't". - Newline:
print('\n'). - F-Strings:
f'Price {cost:.2f}', f'{ratio:.2%}'.
Data Types
int (whole), float (decimal), str (text), bool (True/False).- Input:
input() (returns string), int(input()) (converts to integer).
Decision Making
age = int(input('Enter your age: ')) if age >= 18: print('You can vote') else: print('You cannot vote yet')
Operators
== (equal), != (not equal), >= (greater/equal), < (less than).
Lists and Slicing
- Indexing:
data = [1, 'hello', 5.5]. data[0] is 1. Negative indexing starts from -1. - Slicing:
data[1:3] (index 1 to 2), data[:2] (start to 1), data[2:] (2 to end). - Operations:
append(x), extend(list2), insert(i, x), pop(), remove(x), index(5).
Dictionaries
phone_nums = {'Debby': 999, 'Abe': 555}.- Access:
phone_nums['Wei']. - Delete:
del phone_nums['Abe'].
Loops and Flow Control
- While:
while count <= 5:. Use break to exit. - For: Iterates through lists, strings, or dictionary keys.
- Range:
range(start, stop, step). - List Comprehensions:
[d**2 for d in data if d > 0].
Functions and Scope
- Define:
def add(a, b): return a + b. - Scope: Global vs Local variables.
NumPy Basics
np.array([[1,2],[3,4]]).- Attributes:
B.shape, B.dtype. - Functions:
np.zeros(), np.arange(), np.linspace(), np.mean(), np.std().
Matplotlib and Seaborn
- Matplotlib:
plt.plot(), plt.scatter(), plt.hist(), plt.subplots(). - Seaborn:
sns.histplot(), sns.boxplot(), sns.heatmap().
Pandas Data Structures
- Series: 1D labeled array.
s.loc['Label'], s.iloc[0]. - DataFrame: 2D table.
df['Column'], df.iloc[row, col]. - Operations:
drop(), sort_values(), apply(), concat(), describe(). - Date Parsing:
pd.to_datetime() using format codes like %Y-%m-%d.
