Using Pandas, I have pulled in a CSV file and then created a series of the data to find out which days of the week have the most crashes:
crashes_by_day = bc['DAY_OF_WEEK'].value_counts()
I have then plotted this out, but of course it plots them in the same ranked order as the series.
crashes_by_day.plot(kind='bar')
What is the most efficient way to re-rank these to Mon, Tue, Wed, Thur, Fri, Sat, Sun?
Do I have to break it out into a list? Thanks.
You can use Ordered Categorical and then sort_index:
print bc
DAY_OF_WEEK a b
0 Sunday 0.7 0.5
1 Monday 0.4 0.1
2 Tuesday 0.3 0.2
3 Wednesday 0.4 0.1
4 Thursday 0.3 0.6
5 Friday 0.4 0.9
6 Saturday 0.3 0.2
7 Sunday 0.7 0.5
8 Monday 0.4 0.1
9 Tuesday 0.3 0.2
10 Wednesday 0.4 0.1
11 Thursday 0.3 0.6
12 Friday 0.4 0.9
13 Saturday 0.3 0.2
14 Sunday 0.7 0.5
15 Monday 0.4 0.1
16 Tuesday 0.3 0.2
17 Wednesday 0.4 0.1
18 Thursday 0.3 0.6
19 Friday 0.4 0.9
20 Saturday 0.3 0.2
bc['DAY_OF_WEEK'] = pd.Categorical(bc['DAY_OF_WEEK'], categories=
['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday', 'Sunday'],
ordered=True)
print bc['DAY_OF_WEEK']
0 Sunday
1 Monday
2 Tuesday
3 Wednesday
4 Thursday
5 Friday
6 Saturday
7 Sunday
8 Monday
9 Tuesday
10 Wednesday
11 Thursday
12 Friday
13 Saturday
14 Sunday
15 Monday
16 Tuesday
17 Wednesday
18 Thursday
19 Friday
20 Saturday
Name: DAY_OF_WEEK, dtype: category
Categories (7, object): [Monday < Tuesday < Wednesday < Thursday < Friday < Saturday < Sunday]
crashes_by_day = bc['DAY_OF_WEEK'].value_counts()
crashes_by_day = crashes_by_day.sort_index()
print crashes_by_day
Monday 3
Tuesday 3
Wednesday 3
Thursday 3
Friday 3
Saturday 3
Sunday 3
dtype: int64
crashes_by_day.plot(kind='bar')
Next possible solution without Categorical is set sorting by mapping:
crashes_by_day = bc['DAY_OF_WEEK'].value_counts().reset_index()
crashes_by_day.columns = ['DAY_OF_WEEK', 'count']
print crashes_by_day
DAY_OF_WEEK count
0 Thursday 3
1 Wednesday 3
2 Friday 3
3 Tuesday 3
4 Monday 3
5 Saturday 3
6 Sunday 3
days = ['Monday','Tuesday','Wednesday','Thursday','Friday','Saturday', 'Sunday']
mapping = {day: i for i, day in enumerate(days)}
key = crashes_by_day['DAY_OF_WEEK'].map(mapping)
print key
0 3
1 2
2 4
3 1
4 0
5 5
6 6
Name: DAY_OF_WEEK, dtype: int64
crashes_by_day = crashes_by_day.iloc[key.argsort()].set_index('DAY_OF_WEEK')
print crashes_by_day
count
DAY_OF_WEEK
Monday 3
Tuesday 3
Wednesday 3
Thursday 3
Friday 3
Saturday 3
Sunday 3
crashes_by_day.plot(kind='bar')
