Building a workflow

Introduction to Python for Developers

Jasmin Ludolf

Senior Data Science Content Developer

Complex workflows

Loops through data structures
- for, while
Evaluate multiple conditions
- if, elif, else, >, >=, <, <=, ==, !=
Update variables
- +=
Return outputs
- print()

The "in" keyword

in = check if a value is in a variable/data structure

recipe = {"pasta": 500, "tomatoes": 400, 
          "garlic": 15, "basil": 20}


if "pasta" in recipe.keys():
    print(True)
else:
    print(False)

True

Faster than looping through every key

The "not" keyword

not = check if a condition is not met
Useful for validating that something is missing

pantry_items = ["flour", "sugar", "olive oil"]

# Check if "salt" is NOT in our pantry
if "salt" not in pantry_items:
    print(True)
else:
    print(False)

True

The "and" keyword

and = check if multiple conditions are met
Use when multiple requirements must be met

pasta_quantity = 600
olive_oil_quantity = 30

# Check if we have enough of BOTH ingredients
if pasta_quantity >= 500 and olive_oil_quantity >= 30:
    print(True)
else:
    print(False)

True

The "or" keyword

or = check if one (or more) condition is met
Use when any of several options are acceptable

pasta_quantity = 600
olive_oil_quantity = 30

# Check if we have enough of EITHER ingredient
if pasta_quantity >= 500 or olive_oil_quantity >= 30:
    print(True)
else:
    print(False)

True

Adding/subtracting from variables

Combine keywords with other techniques to build complex workflows

ingredients_checked = 0
for ingredient in recipe_list:
    # ingredients_checked = ingredients_checked + 1
    ingredients_checked += 1

items_to_buy = 10
for item in shopping_list:
    # items_to_buy = items_to_buy - 1
    items_to_buy -= 1

+= adds to a variable, -= subtracts from it
Other ways to update variables

Appending

Store information that meets specific criteria in a list

# Create empty list to hold results
shopping_list = []


# Loop through recipe ingredients
for ingredient, qty_needed in recipe.items():

    # Check if we need to buy it
    if ingredient not in pantry:

        # Add to shopping list
        shopping_list.append(ingredient)

Appending

print(shopping_list)

['tomatoes', 'salt']

Let's practice!

Introduction to Python for Developers