繪製在Python從CSV

Question

編輯只提取特定的列：作爲建議縮短的問題：

很新的蟒蛇和編程，我想第1和第4列繪製成數（x）的日誌（y）圖。說實話，我不知道如何從中提取我需要的兩列。

16:58:58 | 2.090 | 26.88 | 1.2945E-9 | 45.8 
16:59:00 | 2.031 | 27.00 | 1.3526E-9 | 132.1 
16:59:02 | 2.039 | 26.90 | 1.3843E-9 | 178.5 
16:59:04 | 2.031 | 26.98 | 1.4628E-9 | 228.9 
16:59:06 | 2.031 | 27.04 | 1.5263E-9 | 259.8 
16:59:08 | 2.027 | 26.84 | 1.6010E-9 | 271.8 

Answer 1

使用熊貓：

import pandas as pd 
df = pd.read_csv("data.txt", delimiter="\s[|]\s+", header=None, index_col=0) 
df.plot(y=4) 

（請注意，這忽略了對數縮放，因爲它不是明確的時間的對數應該是多少）

Answer 2

如果你不想使用優秀的pandas，這裏是一種蒸汽方式。

import matplotlib.pyplot as plt 
import math 
import datetime as dt 

test = """16:58:58 | 2.090 | 26.88 | 1.2945E-9 | 45.8\n 
16:59:00 | 2.031 | 27.00 | 1.3526E-9 | 132.1\n 
16:59:02 | 2.039 | 26.90 | 1.3843E-9 | 178.5\n 
16:59:04 | 2.031 | 26.98 | 1.4628E-9 | 228.9\n 
16:59:06 | 2.031 | 27.04 | 1.5263E-9 | 259.8\n 
16:59:08 | 2.027 | 26.84 | 1.6010E-9 | 271.8\n""" 

lines = [line for line in test.splitlines() if line != ""] 

# Here is the real code 
subset = [] 

for line in lines: 
    parts = line.split('|') 
    ts = dt.datetime.strptime(parts[0].strip(), "%H:%M:%S") 
    num = math.log(float(parts[3].strip())) 
    subset.append((ts, num)) 

# now there is a list of tuples with your datapoints, looking like 
# [(datetime.datetime(1900, 1, 1, 16, 58, 58), 1.2945E-9), (datetime.datetime(1900, 1, 1, 16, 59), ...] 
# I made this list intentionally so that you can see how one can gather everything in a tidy way from the 
# raw string data. 

# Now lets separate things for plotting 
times = [elem[0] for elem in subset] 
values = [elem[1] for elem in subset] 

# now to plot, I'm going to use the matplotlib plot_date function. 
plt.figure() 
plt.plot_date(times, values) 
# do some formatting on the date axis 
plt.gcf().autofmt_xdate() 
plt.show()