The retail business network is the specific business units that sell goods and services to the final customer. Its main business activities are direct sales of goods to urban and rural residents and social groups, after the purchasing from the wholesale enterprises. It is a direct provision of goods for urban and rural residents. Retail site selection has a long-term and fixed property which is hard to change once determined. The use of GIS spatial analysis functions can make both graphics vectorization and buffer analysis. The application of GIS technology and model in commercial locations contributes to carrying out the characteristics of the business district and status analysis. It can also help operators to determine the commercial retail net, adjust the business strategy and improve the practical operation as well as analysis ability.

As the main part of urban land, commercial land has become an important research object of traditional structural theory of retail. B.J.Garner’s spatial model (Burns, 1980), D.L.Huff’s commercial retail gravity model (KUNC et al., 2012), and B.J.Garrison’s research on the development of the theory of the central place (Zhong et al., 2017), all of which have been devoted to the study of the internal commercial grade system. Due to the limitations of technology and analytical methods, this kind of theoretical research is limited in the process of development and practice.

In the commercial retail net selection, in order to meet the requirements of the spatial information of the decision makers in the commercial enterprises, GIS can output the statistical analysis results of the relevant business data which are closely related to geographical location (such as population, traffic, transportation, market competition, etc.) to the user through graphics, charts, etc.. The function of spatial analysis and visual expression can also be used to make the site more scientific and intuitive, improve the location efficiency and improve the quality of site selection.

In Comparison with the common positioning methods, the position analysis by ArcGIS has the following four advantages:
a) All coordinates information can be aggregated on the map directly and visually to reflect the location of the site around the population distribution, facilities layout, traffic conditions and other location information, which can contribute to scientific analysis and decision making.
b) The user can be layered on the information needed, such as stacking operation through the control of different map layers when exploring data using ArcGIS. The style and style of these elements can also be set, which can conducive to the location of scientific decision-making.
c) Spatial analysis can be carried out directly. To give the distribution pattern of customers inside the trading area, various types of analysis can be carried out according to the specific situations. This research method is able to do the statistical analysis of the number of commercial retail nets and the saturation of the market, referring to the road, the administrative area and the designated space area. Information for the establishment and revocation of the network can also be provided in this way.
d) Users can quickly find the available market space by the analysis of thematic maps. The method of location analysis based on GIS can also be used for simulation analysis and evaluation and prediction after the determination of the preselected position. The preferred solution can be determined on the basis of this method, the feedback to the user can be given in a qualitative and quantitative manner, which can greatly improves the efficiency of decision making.

illness
In figure 3, two groups of households are in low condition of health:
a) People live in regions without any groceries which is the west part on the map. According to figure 2, although this part of households mostly have cars or vans, no groceries near them means they must spend a lot of time on driving to get enough kind of food. From figure 1, this part of people is mostly employed, which means, they do not have enough spare time to buy fresh food every day after work. Their food choice may be limited by the small groceries around them.
b) Residents in the west part of Sheffield who is mostly unemployed. Unemployed status make them cannot afford the price for well-balanced diet. Small groceries around them can only provide limited variety of food. Most of them are always in unhealthy diet, which contributes to a higher percentage of limiting long-term illness.
Since the middle of the 1890s, Britain has been paying more attention to the areas with poor basic retail services, such as food retailers (Cummins and Macintyre, 2002). Areas like the north-west part in figure 3, residents there are in low health condition relatively where can be considered as “food deserts” (Reisig and Hobbiss, 2000). The UK Low Income Project Team definite it as an areas of relative exclusion where people experience physical and economic barriers to accessing healthy food (Greenmyghetto, accessed online).

1-no-car2-unemployment

(figure1,2,3 are created by author)

Food deserts (Wrigley, 2002) often appears in poor areas, Part of the reason is that residents in poor areas are lack of short-term (no car) or long-term (lack of residential choice due to lack of means) mobility. Figure 1 shows the retail geography related to car ownership in Sheffield (households who do not have a car or van mostly live in the south-east part of Sheffield where transport condition is relatively good). The poor regions are lack of big retailers(as figure 2 shows), so low – income families with no cars tend to buy food and their daily needs in nearby retail groceries. These groceries are often too small to have varieties of fresh food, but the price there are always higher than the bigger ones (hhamil, 2010). That is to say, People’s diet will be influenced by the type and availability of local food stores (Cummins and Macintyre, 2002b), which result to the retail geographies of figure 1 (households live in the south-east part of Sheffield who do not have a car or van mostly have a limiting long-term illness).
Implication for policy makers about how to enable the access to healthy for poor is that, diversification and affordable food should be ensured even after the improvement of the socio-economic level of the individual in an area(Eisenhauer, 2001) (Zenk et al., 2005). This relationship can be seen in Sheffield, which may lead to health inequalities and may exacerbate public health problems related to social and economic exploitation (Wrigley, 2002b) (Wrigley, Warm, and Margetts, 2003) . Living in such a food insecurity condition may also result in socio-familial (modified eating patterns, disrupted household dynamics) and psychological consequences (distress, guilt), the fundamental reason for food insecurity may be the physical inaccessibility or monetary constraints (Apparicio, Cloutier, and Shearmur, 2007b).