在DataFrame中进行迭代并写下满足条件的值的索引 [英] Iterating in DataFrame and writing down the index of the values where a condition is met

问题描述

我有一个由20行和2500列组成的数据. 每列都是唯一的乘积，行是时间序列，测量结果.因此，每种产品都要进行20次测量，总共有2500种产品.

I have a data made of 20 rows and 2500 columns. Each column is a unique product and rows are time series, results of measurements. Therefore each product is measured 20 times and there are 2500 products.

我的数据定义为DataFrame，我想写下所有列(产品，这样我最后会有一个数组.

My data is defined as DataFrame and I want to write down the number of the row (index) where a specific condition (such as: x> 3) is met for the first time, for all columns(products, so that I will have an array in the end.

我尝试使用循环和迭代，但是执行失败.

I tried using loops and iterrow but failed at executing.

P.S:我使用idxmax()来获取最大值的行ID，但这一次我想获取第一次满足条件然后中断的单元格的索引.

P.S: I used idxmax() in order to get the row id of max value but this time I want to get the index of the cell where a condition is met for the first time and then break.

推荐答案

只需使用.gt + .idxmax，这将为您第一次满足条件提供索引.

Simply use .gt + .idxmax, which will give you the index of the first time your condition is met.

import pandas as pd
import numpy as np

np.random.seed(12)
df = pd.DataFrame(np.random.randint(1,5,(20,2500)))

df.gt(3).idxmax()
#0        0
#1        0
#2        4
#3        4
#4        1
#...
#2496     8
#2497     0
#2498     5
#2499     1

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