최근 Analysis with 프로그래밍에 Planet Python이 추가되었습니다. 저는 이 웹사이트의 첫 번째 게스트 블로거 중 한 명으로서 Python을 통해 데이터 분석을 시작하는 방법을 공유하려고 왔습니다. 구체적인 내용은 다음과 같습니다.
데이터 가져오기
로컬 또는 웹 CSV 파일 가져오기
데이터 변환
데이터 통계 설명
단일 표본 t -테스트;
시각화
사용자 정의 기능을 만듭니다.
import pandas as pd # Reading data locally df = pd.read_csv('/Users/al-ahmadgaidasaad/Documents/d.csv') # Reading data from web data_url = "https://raw.githubusercontent.com/alstat/Analysis-with-Programming/master/2014/Python/Numerical-Descriptions-of-the-Data/data.csv" df = pd.read_csv(data_url)
# Head of the data print df.head() # OUTPUT Abra Apayao Benguet Ifugao Kalinga 0 1243 2934 148 3300 10553 1 4158 9235 4287 8063 35257 2 1787 1922 1955 1074 4544 3 17152 14501 3536 19607 31687 4 1266 2385 2530 3315 8520 # Tail of the data print df.tail() # OUTPUT Abra Apayao Benguet Ifugao Kalinga 74 2505 20878 3519 19737 16513 75 60303 40065 7062 19422 61808 76 6311 6756 3561 15910 23349 77 13345 38902 2583 11096 68663 78 2623 18264 3745 16787 16900
# Extracting column names print df.columns # OUTPUT Index([u'Abra', u'Apayao', u'Benguet', u'Ifugao', u'Kalinga'], dtype='object') # Extracting row names or the index print df.index # OUTPUT Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78], dtype='int64')
# Transpose data print df.T # OUTPUT 0 1 2 3 4 5 6 7 8 9 Abra 1243 4158 1787 17152 1266 5576 927 21540 1039 5424 Apayao 2934 9235 1922 14501 2385 7452 1099 17038 1382 10588 Benguet 148 4287 1955 3536 2530 771 2796 2463 2592 1064 Ifugao 3300 8063 1074 19607 3315 13134 5134 14226 6842 13828 Kalinga 10553 35257 4544 31687 8520 28252 3106 36238 4973 40140 ... 69 70 71 72 73 74 75 76 77 Abra ... 12763 2470 59094 6209 13316 2505 60303 6311 13345 Apayao ... 37625 19532 35126 6335 38613 20878 40065 6756 38902 Benguet ... 2354 4045 5987 3530 2585 3519 7062 3561 2583 Ifugao ... 9838 17125 18940 15560 7746 19737 19422 15910 11096 Kalinga ... 65782 15279 52437 24385 66148 16513 61808 23349 68663 78 Abra 2623 Apayao 18264 Benguet 3745 Ifugao 16787 Kalinga 16900
print df.ix[:, 0].head() # OUTPUT 0 1243 1 4158 2 1787 3 17152 4 1266 Name: Abra, dtype: int64
print df.ix[10:20, 0:3] # OUTPUT Abra Apayao Benguet 10 981 1311 2560 11 27366 15093 3039 12 1100 1701 2382 13 7212 11001 1088 14 1048 1427 2847 15 25679 15661 2942 16 1055 2191 2119 17 5437 6461 734 18 1029 1183 2302 19 23710 12222 2598 20 1091 2343 2654
print df.drop(df.columns[[1, 2]], axis = 1).head() # OUTPUT Abra Ifugao Kalinga 0 1243 3300 10553 1 4158 8063 35257 2 1787 1074 4544 3 17152 19607 31687 4 1266 3315 8520
print df.describe() # OUTPUT Abra Apayao Benguet Ifugao Kalinga count 79.000000 79.000000 79.000000 79.000000 79.000000 mean 12874.379747 16860.645570 3237.392405 12414.620253 30446.417722 std 16746.466945 15448.153794 1588.536429 5034.282019 22245.707692 min 927.000000 401.000000 148.000000 1074.000000 2346.000000 25% 1524.000000 3435.500000 2328.000000 8205.000000 8601.500000 50% 5790.000000 10588.000000 3202.000000 13044.000000 24494.000000 75% 13330.500000 33289.000000 3918.500000 16099.500000 52510.500000 max 60303.000000 54625.000000 8813.000000 21031.000000 68663.000000
from scipy import stats as ss # Perform one sample t-test using 1500 as the true mean print ss.ttest_1samp(a = df.ix[:, 'Abra'], popmean = 15000) # OUTPUT (-1.1281738488299586, 0.26270472069109496)
t 통계
prob : 부동 소수점 또는 배열 유형
양측 p-값 양측 확률 값
print ss.ttest_1samp(a = df, popmean = 15000) # OUTPUT (array([ -1.12817385, 1.07053437, -65.81425599, -4.564575 , 6.17156198]), array([ 2.62704721e-01, 2.87680340e-01, 4.15643528e-70, 1.83764399e-05, 2.82461897e-08]))
시각화
# Import the module for plotting import matplotlib.pyplot as plt plt.show(df.plot(kind = 'box'))
import matplotlib.pyplot as plt pd.options.display.mpl_style = 'default' # Sets the plotting display theme to ggplot2 df.plot(kind = 'box')
# Import the seaborn library import seaborn as sns # Do the boxplot plt.show(sns.boxplot(df, widths = 0.5, color = "pastel"))
plt.show(sns.violinplot(df, widths = 0.5, color = "pastel"))
plt.show(sns.distplot(df.ix[:,2], rug = True, bins = 15))
with sns.axes_style("white"): plt.show(sns.jointplot(df.ix[:,1], df.ix[:,2], kind = "kde"))
plt.show(sns.lmplot("Benguet", "Ifugao", df))
创建自定义函数
在Python中,我们使用def函数来实现一个自定义函数。例如,如果我们要定义一个两数相加的函数,如下即可:
def add_2int(x, y): return x + y print add_2int(2, 2) # OUTPUT 4
顺便说一下,Python中的缩进是很重要的。通过缩进来定义函数作用域,就像在R语言中使用大括号{…}一样。这有一个我们之前博文的例子:
产生10个正态分布样本,其中u=3和o.
基于95%的置信度,计算 x_bar 和 x_bar2 ;
重复100次; 然后
计算出置信区间包含真实均值的百分比
Python中,程序如下:
import numpy as np import scipy.stats as ss def case(n = 10, mu = 3, sigma = np.sqrt(5), p = 0.025, rep = 100): m = np.zeros((rep, 4)) for i in range(rep): norm = np.random.normal(loc = mu, scale = sigma, size = n) xbar = np.mean(norm) low = xbar - ss.norm.ppf(q = 1 - p) * (sigma / np.sqrt(n)) up = xbar + ss.norm.ppf(q = 1 - p) * (sigma / np.sqrt(n)) if (mu > low) & (mu < up): rem = 1 else: rem = 0 m[i, :] = [xbar, low, up, rem] inside = np.sum(m[:, 3]) per = inside / rep desc = "There are " + str(inside) + " confidence intervals that contain " "the true mean (" + str(mu) + "), that is " + str(per) + " percent of the total CIs" return {"Matrix": m, "Decision": desc}
上述代码读起来很简单,但是循环的时候就很慢了。下面针对上述代码进行了改进,这多亏了 Python专家。
import numpy as np import scipy.stats as ss def case2(n = 10, mu = 3, sigma = np.sqrt(5), p = 0.025, rep = 100): scaled_crit = ss.norm.ppf(q = 1 - p) * (sigma / np.sqrt(n)) norm = np.random.normal(loc = mu, scale = sigma, size = (rep, n)) xbar = norm.mean(1) low = xbar - scaled_crit up = xbar + scaled_crit rem = (mu > low) & (mu < up) m = np.c_[xbar, low, up, rem] inside = np.sum(m[:, 3]) per = inside / rep desc = "There are " + str(inside) + " confidence intervals that contain " "the true mean (" + str(mu) + "), that is " + str(per) + " percent of the total CIs" return {"Matrix": m, "Decision": desc}
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