Free tools Windows power users keep installed
One-click scans. No signup required.
Use dict.update() to add entries to an existing Python dictionary: it changes the dictionary in place, and incoming values replace existing values for matching keys. To merge two dictionaries without changing either input, use the | operator in Python 3.9 or later.
Choose how you want to extend the dictionary
| Need | Use | Effect |
|---|---|---|
| Add entries to an existing dictionary | d.update(other) |
Changes d in place; returns None; incoming values replace conflicts. |
| Merge two dictionaries and preserve both originals | merged = left | right |
Creates a new dictionary; values from right win conflicts. Requires Python 3.9 or later. |
| Update an existing dictionary with operator syntax | left |= other |
Changes left in place. Requires Python 3.9 or later. |
| Add or replace one entry | d[key] = value |
Sets the value for that key. |
Use update() to add or replace entries
Call update() on the dictionary you want to change. It accepts another mapping, an iterable of key-value pairs, or keyword arguments whose names are valid Python identifiers. If a key is already present, the value from the input replaces the old value.
settings = {"theme": "light", "font_size": 12}
settings.update({"theme": "dark", "show_tips": True})
print(settings)
# {'theme': 'dark', 'font_size': 12, 'show_tips': True}You can also pass pairs when your data is not already in a dictionary:
d = {"a": 1}
d.update([("b", 2), ("c", 3)])
print(d)
# {'a': 1, 'b': 2, 'c': 3}For the full list of accepted inputs and behavior, see the Python documentation for dictionary methods.
#1 Best Overall
- Read Before You Buy — No Video Output: These adapters support charging and USB 2.0 data transfer, but cannot transmit video signals. Except for standard USB webcams (which use USB data only), they are not compatible with HDMI/DisplayPort cables, video-capable USB-C hubs, or docking stations with video output.
- Convert USB-A Ports to USB-C: Designed to connect USB-C earphones, cables, flash drives, card readers, and other USB-C accessories to standard USB-A ports. Plug-and-play with no drivers or software required.
- Aluminum Alloy Housing: Built with a sturdy aluminum alloy shell that aids in heat dissipation and protects against daily wear and scratches. Designed to maintain a stable and secure connection.
- Compact & Travel-Friendly: The ultra-compact design allows the adapter to stay plugged into your device without blocking adjacent ports or adding bulk, reducing wear and tear on your original USB ports.
- 12-Month Warranty: Backed by a 12-month manufacturer warranty for peace of mind. Designed to meet strict quality control standards for reliable everyday performance.
Use | to create a merged dictionary
In Python 3.9 and later, left | right returns a new dictionary. It leaves the original dictionaries unchanged, and the value from the right-hand dictionary wins if both contain the same key.
base = {"timeout": 10, "retries": 2}
custom = {"timeout": 30}
merged = base | custom
print(merged)
# {'timeout': 30, 'retries': 2}
print(base)
# {'timeout': 10, 'retries': 2}The | operator requires dictionary operands. PEP 584, which introduced dictionary union, describes conflict handling as keeping the rightmost value: PEP 584: Add Union Operators To dict.
Rank #2
- 5-in-1 USB-C Hub: Experience comprehensive connectivity featuring a Power Delivery input, two USB-A 2.0 ports, a USB-A 3.0 port, and an HDMI port. (Note: The USB-C power delivery input port is only for connecting an external wall charger to power your laptop and cannot power peripheral devices.)
- 90W Pass-Through Charging: Achieve optimal charging with 90W pass-through power to your laptop, supported by a total input of 100W, with the hub reserving 10W for operational efficiency. (Note: Wall charger not included.)
- Quick Data Transfers: Accelerate your productivity with rapid data transfers using a high-speed 5Gbps USB 3.0 port and two 480Mbps USB 2.0 ports.
- 4K HDMI Display: Enhance your visual experience with a hub capable of delivering 4K resolution at 30Hz in both mirror and extend modes. Please note that this hub is compatible with MacBook (macOS 12 and newer), Windows 10 and 11, ChromeOS, and laptops equipped with DP Alt Mode and Power Delivery. Note: This device is not compatible with Linux.
- What You Get: Anker USB-C Hub (5-in-1, 4K HDMI), welcome guide, 18-month warranty, and our friendly customer service.
Use |= for an in-place merge
Also added in Python 3.9, |= updates the dictionary on its left. Unlike |, its right-hand input can be a mapping or an iterable of key-value pairs, like the inputs accepted by update().
settings = {"theme": "light"}
settings |= [("show_tips", True)]
print(settings)
# {'theme': 'light', 'show_tips': True}Append to a value or merge nested dictionaries explicitly
Dictionary update operates at the top level: it replaces the value associated with a duplicate key. It does not append to a list value or recursively combine nested dictionaries. Choose the value-level operation that matches your goal.
Rank #3
- Sleek 7-in-1 USB-C Hub: Features an HDMI port, two USB-A 3.0 ports, and a USB-C data port, each providing 5Gbps transfer speeds. It also includes a USB-C PD input port for charging up to 100W and dual SD and TF card slots, all in a compact design.
- Flawless 4K@60Hz Video with HDMI: Delivers exceptional clarity and smoothness with its 4K@60Hz HDMI port, making it ideal for high-definition presentations and entertainment. (Note: Only the HDMI port supports video projection; the USB-C port is for data transfer only.)
- Double Up on Efficiency: The two USB-A 3.0 ports and a USB-C port support a fast 5Gbps data rate, significantly boosting your transfer speeds and improving productivity.
- Fast and Reliable 85W Charging: Offers high-capacity, speedy charging for laptops up to 85W, so you spend less time tethered to an outlet and more time being productive.
- What You Get: Anker USB-C Hub (7-in-1), welcome guide, 18-month warranty, and our friendly customer service.
Append to a list stored under a key
d = {"items": ["book"]}
d["items"].append("pen")
print(d)
# {'items': ['book', 'pen']}Update a nested dictionary
To preserve existing nested entries while adding or replacing selected ones, update that nested dictionary directly:
settings = {"display": {"theme": "light", "font_size": 12}}
settings["display"].update({"theme": "dark"})
print(settings)
# {'display': {'theme': 'dark', 'font_size': 12}}Avoid the common return-value mistake
update() changes the dictionary and returns None. Do not assign its result back to the same variable:
Rank #4
- Dual Converters, Infinite Potential：Includes 2× USB C male to USB A female adapters and 2× USB A male to USB C female adapters. Perfect for a wide range of uses—tablets with Bluetooth keyboards, expand USB ports on macbook, and more. Two different converters for all your daily needs
- Next-Level 10Gbps & 3A Charging: No more slow 480Mbps, this usb to usb c adapter has a transfer speed of up to 10Gbps, allowing you to do more transferring in less time. This usb adapter fits both USB A and USB C charger, supporting up to 3A fast charging
- Upgraded Exquisite Craftsmanship: With an aluminum alloy housing and metal connector, the usbc to usb adapter is extremely durable and sturdy. Rigorously tested to withstand more than 10,000 times of plugging and unplugging, ensuring long-lasting performance
- Broad Compatible: The usb c to usb adapter widely supports all USB C/ USB A devices like laptops, tablets, cellphones, car chargers, and phone chargers. Such as compatible with MacBook Pro/Air 2023/2022, Thunderbolt 4/3 Devices,Apple MagSafe Watch 9/8/7/SE/Ultra, iPad Pro 2022/2021, Samsung Galaxy S23/S20/S10, and iPhone 17/16/15 Pro. Plug and play
- Please Note: To reach 10Gbps speed, keep the cable under 3.3 ft. For USB A Male to USB C adapters, try flipping the USB C connector. USB C Male to USB A adapters support bidirectional 10Gbps transfer within 3.3 ft
d = {"a": 1}
d = d.update({"b": 2}) # d is now NoneCall d.update(...) on its own line when you want an in-place change. Use merged = left | right when you need a new dictionary.
How key order behaves
When a mapping supplies new keys, those keys are added in that mapping’s order if the mapping type has an order. Existing keys keep their positions when their values are replaced. PEP 584 explains the ordering rationale for dictionary union and update operators.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Quick Recap
Best Value
- 5-in-1 Connectivity: Equipped with a 4K HDMI port, a 5 Gbps USB-C data port, two 5 Gbps USB-A ports, and a USB C 100W PD-IN port. Note: The USB C 100W PD-IN port supports only charging and does not support data transfer devices such as headphones or speakers.
- Powerful Pass-Through Charging: Supports up to 85W pass-through charging so you can power up your laptop while you use the hub. Note: Pass-through charging requires a charger (not included). Note: To achieve full power for iPad, we recommend using a 45W wall charger.
- Transfer Files in Seconds: Move files to and from your laptop at speeds of up to 5 Gbps via the USB-C and USB-A data ports. Note: The USB C 5Gbps Data port does not support video output.
- HD Display: Connect to the HDMI port to stream or mirror content to an external monitor in resolutions of up to 4K@30Hz. Note: The USB-C ports do not support video output.
- What You Get: Anker 332 USB-C Hub (5-in-1), welcome guide, our worry-free 18-month warranty, and friendly customer service.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
