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UL 1971: is there a tolerance on strobe flash rates?

UL 1971 27.1.3(a) requires that listed strobes used for fire alarm signaling to hearing-impaired occupants flash at between 1 and 2 flashes per second: a) Signaling lights shall produce a candela output in effective intensity in accordance with Tables 27.1 – 27.3 and Figures 27.1 – 27.3. The flash rate shall not be less than […]

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Linux Mastering Development

Prepend user-defined string to all files and folders recursively using find and rename

Prepend user-defined string to all files and folders recursively using find and rename. I’d like to prepend “x “ (no quotes) to a directory and all of its contents down through all subdirectories. I’m a beginner using macOS Mojave 10.14.6 and Terminal. I downloaded rename using Homebrew for this purpose. Example: /Old Project /Old Project/Abstract.rtf […]

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User Help

Why do software authors seemingly pay little to no attention to the user’s “maintenance experience”? [closed]

This could very easily turn into a “rant”, so I’m just going to focus on a single piece of software: PostgreSQL on Windows. This database software is installed as a binary installer from a semi-third-party site and called “EnterpriseDB installer”. This fact already is kind of weird, but I understand that the main project has […]

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User Help

In Excel, how do I create a Dynamic Array where each cell is the sum of a corresponding column in another Dynamic Array?

[No VB please.] In brief In Excel, suppose I have a block of numeric data in a Dynamic Array (DA) — i.e. it is spilling and I don’t know (nor want to have to know) the number of rows or columns. I want to sum each column and end up with those sums also being […]

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User Help

I’m a computer person with an interest in numbers and calculations, but have never made a spreadsheet. Is this unusual? [closed]

I’ve looked at various spreadsheet programs running (Excel, Star/Libre/Open Office, etc.), and I’ve played around with them casually, and thought to myself: Hm! This probably would be useful in certain situations! … but never once used them to make any kind of calculation, for myself or anyone/anything else. Every time I’ve needed to make any […]

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Mastering Development

Python (pandas): Using decorators using pandas API

I’m quite new to decorators and classes in general on Python, but have a question if there is a better way to decorate pandas objects. An an example, I have written the following to create two methods — lisa and wil: import numpy as np import pandas as pd test = np.array([[‘john’, ‘meg’, 2.23, 6.49], […]

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Mastering Development

Preserving Aspect Ratio in Image::Magick’s Thumbnail function

I’m trying to use the Perl Image::Magick library to use ImageMagick’s thumbnail function. Everything I read suggests that ImageMagick preserves aspect ratio when it is given both a width and height, almost functioning more like max-width and max-height in CSS parlance. However, in practice, it seems to be jamming the image into the dimensions I […]

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Development

Speeding up operations on large arrays & datasets (Pandas slow, Numpy better, further improvements?)

I have a large dataset comprising millions of rows and around 6 columns. The data is currently in a Pandas dataframe and I’m looking for the fastest way to operate on it. For example, let’s say I want to drop all the rows where the value in one column is “1”. Here’s my minimal working […]