pythonbeginner
Pandas read_csv with Explicit Dtypes
Specify column dtypes on CSV read to avoid costly inference and prevent silent type coercion.
pythonPress ⌘/Ctrl + Shift + C to copy
import pandas as pd
dtypes = {
'id': 'int32',
'user_id': 'int32',
'amount': 'float32',
'category': 'category',
'status': 'category',
'is_fraud': 'bool',
}
df = pd.read_csv(
'transactions.csv',
dtype=dtypes,
parse_dates=['created_at'],
usecols=list(dtypes) + ['created_at'],
low_memory=False,
)
print(df.dtypes)
print(df.memory_usage(deep=True).sum() / 1e6, 'MB')Use Cases
- fast CSV loading
- memory control
- type safety
Tags
Related Snippets
Similar patterns you can reuse in the same workflow.
pythonintermediate
Read Large CSV in Chunks with Pandas
Process CSV files larger than RAM by reading in chunks — memory-efficient ETL pattern for data pipelines.
Best for: Processing multi-GB CSV files without running out of memory
#pandas#csv
pythonintermediate
Pandas Vectorised Operations vs Apply
Compare apply vs vectorised pandas operations for performance-critical column transformations.
Best for: feature engineering
#pandas#vectorization
pythonintermediate
Pandas Memory Reduction via Dtypes
Reduce DataFrame memory by 60-80% by downcasting numeric types and using categorical columns.
Best for: large dataset loading
#pandas#memory
pythonintermediate
Pandas .eval() for Fast Column Computation
Use DataFrame.eval() for expressive, fast in-place column calculations using numexpr.
Best for: large DataFrame operations
#pandas#eval