What is the easiest way to get the size of a DataFrame in Python?

Use the df.shape attribute and convert it to a list [rows, columns] for direct results.

Can I use len() to find DataFrame dimensions?

Yes, len(df) gives the number of rows, and len(df.columns) gives the number of columns.

Why shouldn't I iterate manually over the DataFrame to count rows or columns?

Manual iteration is slower and error-prone; built-in methods like shape are precise and O(1).

How does this problem relate to pandas core interview patterns?

It tests basic familiarity with DataFrame attributes, a common and simple interview pattern in data manipulation.

What format should I return for Get the Size of a DataFrame?

Return an array [number of rows, number of columns] as specified, not a tuple or other structure.

#2878

Easy

auto_awesomeGet the Size of a DataFrame core interview pattern

LeetCode 题解工作台

获取 DataFrame 的大小

题目描述

DataFrame players:
+-------------+--------+
| Column Name | Type   |
+-------------+--------+
| player_id   | int    |
| name        | object |
| age         | int    |
| position    | object |
| ...         | ...    |
+-------------+--------+

编写一个解决方案，计算并显示 players 的 行数和列数。

将结果返回为一个数组：

[number of rows, number of columns]

返回结果格式如下示例所示。

示例 1：

输入：
+-----------+----------+-----+-------------+--------------------+
| player_id | name     | age | position    | team               |
+-----------+----------+-----+-------------+--------------------+
| 846       | Mason    | 21  | Forward     | RealMadrid         |
| 749       | Riley    | 30  | Winger      | Barcelona          |
| 155       | Bob      | 28  | Striker     | ManchesterUnited   |
| 583       | Isabella | 32  | Goalkeeper  | Liverpool          |
| 388       | Zachary  | 24  | Midfielder  | BayernMunich       |
| 883       | Ava      | 23  | Defender    | Chelsea            |
| 355       | Violet   | 18  | Striker     | Juventus           |
| 247       | Thomas   | 27  | Striker     | ParisSaint-Germain |
| 761       | Jack     | 33  | Midfielder  | ManchesterCity     |
| 642       | Charlie  | 36  | Center-back | Arsenal            |
+-----------+----------+-----+-------------+--------------------+
输出：
[10, 5]
解释：
这个 DataFrame 包含 10 行和 5 列。

lightbulb

解题思路

方法一

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import pandas as pd


def getDataframeSize(players: pd.DataFrame) -> List[int]:
    return list(players.shape)

speed

复杂度分析

指标	值
时间	complexity is O(1) since accessing shape or len attributes does not depend on DataFrame size. Space complexity is also O(1) as only a small list of two integers is returned.
空间	Depends on the final approach

psychology

面试官常问的追问

外企场景

question_mark
Looking for knowledge of DataFrame properties in pandas.
question_mark
Expecting use of shape attribute or equivalent built-in function.
question_mark
Testing understanding of simple, efficient DataFrame operations.

warning

常见陷阱

外企场景

error
Attempting to manually count rows and columns using loops.
error
Returning a tuple instead of a list as required by the problem.
error
Confusing DataFrame shape with DataFrame size (total number of elements).

swap_horiz

进阶变体

外企场景

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Return the total number of elements instead of row and column counts using df.size.
arrow_right_alt
Calculate dimensions for a filtered or sliced DataFrame and return updated counts.
arrow_right_alt
Provide row and column names along with counts in a dictionary instead of a list.

help

常见问题

外企场景

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继续模式

Get the Size of a DataFrame core interview pattern

用同一解题框架扩展到更多题目。

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